s2fieldsofstudy: Chemistry Biology

text:
Design and Characterization of Fast Dissolving Films of Cilnidipine Solid Dispersions

The major problem in formulation of oral films of cilnidipine is that it belongs to BCS Class II moiety. Pharmacologically Cilnidipine is a dihydropyridine (DHP) type of calcium channel antagonist. Unlike other calcium channel antagonists, Cilnidipine blocks the influx of Ca 2+ ions into both vascular smooth muscle at the level of L-type Ca 2+ channels and neuronal cells at the level of N-type Ca 2+ channels. Cilnidipine was absorbed over 2 hours and its bioavailability is 64-90%. Hence there is a need to increase the solubility and oral bioavailability of cilnidipine by formulating it in to solid dispersions and incorporating the same in to the formulation of fast dissolving films which gives fast onset of action. Nine formulations (FC 1 FC 9) of cilnidipine films were prepared and evaluated for their physical characteristics such as thickness, weight variation, folding endurance, drug content uniformity and gave satisfactory results. The compatibility of the drug in the formulation was confirmed by FTIR and DSC studies. The formulations were subjected to disintegration, in vitro drug release studies and formulation FC 6 was found to be best formulation which contain HPMC, PVP as film forming polymers along with cilnidipine solid dispersion with poly ethylene glycol at weight ratio of 1:4 showed excellent film forming characteristics such as disintegration time of 49.3 sec and percentage drug release 97.92 within 8 minutes.

INTRODUCTION
Recently fast dissolving drug delivery system have started gaining popularity and acceptance as new drug delivery systems which aim to enhance safety and efficacy of a drug moiety by formulating into a convenient dosage form for administration and to achieve better patient compliance. They undergo rapid disintegration in the salivary fluids of the oral cavity in less than a minute, where they release the drug 1 . Most of the drug is swallowed orally with the saliva and the absorption of drug takes place in the gastro-intestinal tract. The fast dissolving dosage forms are referred by various names by researchers like quick disintegrating, orally disintegrating, rapidly disintegrating, mouth dissolve or melt in mouth dosage forms 2 . Cilnidipine is calcium channel antagonist, which is used in the treatment of Hypertension. Cilnidipine belongs to class II drug in BCS classification the major problems with its low solubility in biological fluids, which results into poor bioavailability after oral administration and late onset of action. In order to enhance the solubility of cilnidipine and subsequently dissolution and absorption. Solid dispersions of cilnidipine were prepared by melting technique at different drug carrier (PEG 400) weight ratios and were evaluated 3 . The optimized formulation of solid dispersions, Cilnidipine : PEG 400 (1:4) was selected and used in the preparation of cilnidipine films by solvent casting method, which offers superiority over other.

Advantages of cilnidipine fast dissolving film include 4,5
 Patient of increases Hypertension not capable to swallow large quantities of water.
 In case of high blood pressure quick onset of action required because uncontrolled high blood pressure create Strokes, Heart attack, Kidney Problem.
 Hypertension markedly reduces functional ability and extremely restlessness in such cases rapid onset of action required.
 No Marketed cilnidipine film available in India.
 Specially intended to geriatric patients who have problem of swallowing.

Standard Curve of Cilnidipine
Cilnidipine is a yellow fine powder which was practically insoluble in water. Though several methods are reported for its estimation, the UV spectrophotometric method was employed in the ISSN: 2249-3387 www.ajptr.com 208 study. Cilnidipine shows maximum absorbance at 240 nm in simulated saliva pH 6.8. Based on this information, a standard graph was constructed ( Figure No.1).

Preparation of cilnidipine solid dispersion
Cilnidipine and PEG 400 are mixed using mortar and pestle. PEG 400 as carrier in different proportions 1:1, 1:2, 1:3 and 1:4 (drug:carrier) as shown in (Table No.2). To accomplish a homogenous dispersion the mixture is heated at or above the melting point of all the components with constant stirring. It is then cooled to acquire a congealed mass. It is crushed and sieved.

Percentage Practical Yield
Percentage practical yield is calculated to know about percent yield, thus its help in selection of appropriate method of production. Solid dispersions were collected and weighed to determine practical yield (PY) from the following equation ( Figure No The release profile of an entrapped drug predicts how a delivery system might function and gives valuable insight into its in vivo behaviour. In vitro release profile for each solid dispersion as well as pure drug was performed using USP type 2 dissolution apparatus. Sample equivalent to 5 mg of cilnidipine was added to 900ml of phosphate buffer of pH 6.8 at 37±0.5°C and stirred at 75 rpm (Table no.

Evaluation of fast dissolving films a) Physical appearance and surface texture of films:
This parameter was checked simply with visual inspection of films and evaluation of texture by feel or touch.

b) Weight uniformity of films:
Three films of the size 2×2 cm were weighed individually using digital balance and the average weights were calculated.

c) Thickness of films:
Thickness of the films was measured using screw gauge with a least count of 0.01mm at different spots of the films. The thickness was measured at three different spots of the films and average was taken.

d) Folding endurance of patches:
The flexibility of films can be measured quantitatively in terms of what is known as folding endurance. Folding endurance of the films was determined by repeatedly folding a small strip of the ISSN: 2249-3387 www.ajptr.com 210 films (approximately 2x2 cm) at the same place till it broke. The number of times films could be folded at the same place, without breaking gives the value of folding endurance.

e) Drug-polymer interaction study of films:
There is always a possibility of drug-excipients interaction in any formulation due to their intimate contact. The technique employed in this study to know drug-excipients interactions is IR spectroscopy. IR spectroscopy is one of the most powerful analytical techniques which offer the possibility of chemical identification. Infra-red spectra of pure drug cilnidipine and formulations were scanned by using FTIR and DSC, by a thin film method.

f) Drug content uniformity of films:
The films were tested for drug content uniformity by UV Spectrophotometric method. Films of 2×2 cm size were cut from three different places from the casted films. Each film was placed in 100 mL volumetric flask and dissolved in simulated saliva pH 6.8 and 2 mL is taken and diluted with water up to 10 mL. The absorbance of the solution was measured at λ max 240 nm using UV/ visible spectrophotometer (Shimadzu). The percentage drug content was determined.

g) In vitro drug release:
The release rate of cilnidipine fast dissolving oral films was determined by using USP dissolution testing apparatus II at 50 RPM. The film with 2×2 cm was placed in the 500 mL of 6.8 pH simulated saliva as dissolution medium, and temperature was maintained at 37°C. From this dissolution medium, 5 mL of the sample solution was withdrawn at different time intervals. The samples were filtered through Whitman filter paper and absorbance was determined 240 nm using double beam UV-Visible spectrophotometer.

h) Permeation study:
The They were found be physically flexible and dry. The folding endurance was measured manually, by folding the FDF repeatedly at a point till it broke. The breaking time was considered as the end point.
Folding endurance was found to be highest for FC 7 and lowest for FC 6. It was found that the folding endurance of the FDF was affected with increase of carrier concentration. The folding endurance values of the FDF were found to be optimum and therefore, the FDFs exhibited the good physical and mechanical properties. The folding endurance of films was found to be in the range of 321 to 364 (Table No. 5).As all the formulations contain different amount of polymers, the thickness was gradually increased with the amount of polymers. All the film formulations were found to have thickness in the range of 0.14 to 0.23 mm and were observed within the limits.

Weight variation
The randomly selected film strips about 2 × 2 cm areas were cut at different places from the casted film and weight was measured. Weight of film strip units varies from 43.36 to 55.33 mg. The results indicated that selected carriers used in method of solid dispersion preparation, proportion of carrier used have reduced the variation and improved the uniformity of the distribution in casted films (

Drug content
The prepared film formulations were studied for their drug content. The drug was dispersed in the range of 84 % to 98 %. Suggesting that drug was uniformly dispersed in all films.

In vitro dissolution studies
The in-vitro drug release profiles of the formulations in SSF pH 6.8 show differences depending on their composition. The rate of drug release from the HPMC E15 films was significantly lower than the films containing PVP K30 along with the HPMC E15 ( Figure No.10 and 11). This is due to the swelling of the high viscosity HPMC E15 upon contact with the dissolution medium, resulting in the formation of a thick matrix gel. The formulation FC6 films containing combination of HPMC E15 and PVP K30 as hydrophilic polymers shows high percentage of drug release (97.92%) within 8 minutes compared to that of films containing HPMC E15alone and PVA along with HPMC E15 as a polymers.    shows high percentage of drug release within 8 minutes compared to that of films containing HPMC alone as a polymer, combination of HPMC E15 and PVA. Present study reveals that fast dissolving films can be a potential novel drug delivery system for geriatric, pediatric and also for general population.


extfieldsofstudy:
Medicine
Materials Science

text:
New ferrocenyl-containing organic hole-transporting materials for perovskite solar cells in regular (n-i-p) and inverted (p-i-n) architectures

Three triphenylamine derivatives containing ferrocenyl groups (JW6, JW7 and JW8) were synthesized by facile syntheses. Their HOMO levels match the valence band energy of CH3NH3PbI3. The introduction of ferrocenyl was aimed to obtain hole transporting materials with high mobility for perovskite solar cells. JW7 shows higher hole mobility (4.2 10 4 cm V 1 s ) than JW6 (1.3 10 4 cm V 1 s ) and JW8 (1.5 10 4 cm V 1 s ). Their film-forming properties are affected by their molecule structures. The methoxyl and N,N-dimethyl terminal substituents of JW7 and JW8 are beneficial for having better solubility than JW6. The regular mesoporous TiO2-based perovskite solar cells (n-i-p) and the inverted planar heterojunction perovskite solar cells (p-i-n) fabricated using JW7 show the highest power conversion efficiency of 9.36% and 11.43% under 100 mW cm 2 AM1.5G solar illumination. For p-i-n cells, the standard HTM PEDOT-based cell reaches an efficiency of 12.86% under the same conditions.

Introduction
Perovskite solar cells have attracted much attention due to the high photovoltaic performance of the organolead halide. [1][2][3][4][5][6][7] The organolead halide perovskite was used as the light absorber in liquid-based dye-sensitized solar cells (DSSCs), and showed a power conversion efficiency (PCE) of 3.8% in 2009. The initial PCE of the solid-state perovskite solar cells was 9.7% in 2012. 8,9 Recently, PCE of perovskite solar cells has been over 22%. 10 The commonly reported CH 3 NH 3 PbI 3 was used in the rst solidstate PSC, and a solid hole-transport layer was made of 2,20,7,70-tetrakis-(N,N-di-p-methoxyphenylamine)-9,90-spirobiuorene (spiro-OMeTAD), which shows good charge extraction and improves the long-term stability of the device. 9,[11][12][13][14][15] It is necessary to place the perovskite between an ntype semiconductor layer and a p-type semiconductor layer, according to the structure of traditional PSCs, 16 for charge separation and transport in a PSC device. Organic smallmolecule HTMs such as spiro-OMeTAD are commonly used as p-type semiconductor materials for PSCs. Compared with inorganic HTMs and organic polymer HTMs, organic smallmolecule HTMs have the advantages of facile synthesis, exible modication of structure, and easy purication. [17][18][19][20][21][22] Organic small-molecule HTMs can reach high hole mobility by possessing tunable energy levels, suitable solubility in organic solvents, and good lm-forming properties. [23][24][25][26] Ferrocene is an organometallic compound with a sandwich structure. Ferrocene and its derivatives are widely used in electrochemical sensors, biomedicine, chemical catalysts and photovoltaic materials due to their good redox abilities. [27][28][29][30] Ferrocene can also act as a suitable electron-donating unit and can be easily functionalized, due to which it has been reacted with small molecules for conjugation. Ferrocene-containing triphenylamine derivatives have been reported because of their good lightharvesting ability and fast charge regeneration. 31,32 Ferrocenylsubstituted triphenylamines are used as sensitizers in DCCCs, and an inserted p-linker between ferrocene and triphenylamine is benecial for charge transport in the molecule. [33][34][35] Structural changes have a signicant inuence on electron delocalization though the entire molecule. Ferrocenyl-substituted triphenylamines have also been used as p-type redox promoters in electrochromic display devices, and they can form a lm layer by spincoating. 36 Therefore, ferrocene is a promising candidate for photovoltaic materials. In our research, new ferrocenyl-substituted triphenylamine derivatives were synthesized, and they were used as organic small-molecule HTMs to construct PSCs. To the best of our knowledge, this is the rst time that organic small molecules containing ferrocene have been reported in PSCs.
In this study, three new ferrocene-containing compounds (JW6, JW7 and JW8) were prepared, and their structures are shown in Scheme 1. In JW6, JW7 and JW8 molecules, biferrocene groups were connected with triphenylamines via triple bonds, and a double bond was also introduced to link a moiety of triphenylamine, bis(4-methoxyphenyl)methane and 4,4 0 -methylenebis(N,N-dimethylaniline), which can adjust the solubility, energy levels and charge transport. Theoretical calculations were performed to observe the optimized geometric structures and frontier molecular orbitals of the three compounds. Spectral and electrochemical measurements were applied for the determination of light absorption and energy levels. Differential scanning calorimetry (DSC) was performed for analysing the thermal stability of JW6, JW7 and JW8. PSCs based on JW6, JW7 and JW8 were fabricated, and we found that the concentration of HTM solution signicantly inuenced the device performance. In the inverted planar heterojunction perovskite solar cells (p-i-n), the concentration of HTMs was 5 mg mL À1 without any dopant. The PCE of p-i-n cells based on the studied HTMs reached 89% of the PCE of those cells based on the standard HTM (poly (3,4-ethylenedioxythiophene), PEDOT). In devices of the regular mesoporous TiO 2 -based PSCs (n-i-p), different concentrations of HTM solutions were spin-coated by adding only 4-tert-butylpyridine (TBP). A low concentration of 10 mg mL À1 was good for the studied HTM to establish excellent contact with the perovskite layer. Among the three compounds, JW7 showed better photovoltaic performances than JW6 and JW8. The structure-efficiency relationship of these ferrocene-containing HTMs was discussed based on the measurements of J-V characterizations and steady-state and time-resolved photoluminescence (PL) spectra. The hole mobility of the new HTMs was measured by space-charge-limited-current (SCLC), and charge recombination was studied by electrochemical impedance spectroscopy (EIS). Through this research we hope to provide some experimental basis for designing new HTMs for PSCs.

Materials
All the starting materials used in this study were purchased from J&K Chemical, Energy Chemical or Sigma-Aldrich and used without further purication, unless otherwise stated. N,N-Dimethylformamide (DMF) and tetrahydrofuran (THF) were dried using 200 mesh molecular sieve and sodium metal, respectively.

Fabrication of PSCs
In this study, two architectures of PSCs were fabricated. The conventional n-i-p type PSCs (FTO/TiO 2 /perovskite/HTM/Ag) were fabricated according to the published method. 37 The main study was focussed on the inverted p-i-n type of PSCs (ITO/ HTM/perovskite/PCBM/BCP/Ag). In brief, ITO glasses were successively washed using a special cleaner, acetone, water and ethanol, and then covered with HTM layer (5 mg mL À1 ) by spinning at 4000 rpm for 40 s. This rst layer was sintered at 100 C for 10 min. By the sequential deposition method, a perovskite layer was covered on the HTM layer. Aer the perovskite precursor solution (461 mg PbI 2 , 159 mg MAI, 70.9 mL DMSO and 634.92 mL DMF) was spin-coated at 5000 rpm for 25 s in a nitrogen lled glovebox, the device was annealed at 100 C for 10 min. Then, PCBM (20 mg mL À1 ) in CB and BCP (0.5 mg mL À1 ) in isopropanol were spin-coated on the perovskite layer at 4000 rpm for 40 s. The PCBM layer was annealed at 80 C for 10 min, while BCP was only spin-coated on the PCBM layer without any heating. Finally, Ag was vacuum-evaporated on the top of the device as the counter electrode.

Characterizations
1 H NMR and 13 C NMR spectra were recorded on a Bruker AM-400 spectrometer. The chemical shis were reported against TMS. High resolution mass spectra were obtained on a Micromass GCT-TOF mass spectrometer. UV-vis absorption spectra were recorded on a SHIMADZU UV-2600 spectrophotometer. Photoluminescence (PL) measurements were recorded on a HITACHI F-4500 uorescence spectrophotometer at 500 nm excitation wavelength. Cyclic voltammetry (CV) measurements were recorded using a Zennium electrochemical workstation (ZAHNER, Germany) under a three-electrode system, platinum was used as the working electrode, Ag/AgCl electrode was used as the reference electrode, and Pt-wires were used as the counter electrode. Electrochemical impedance spectroscopy (EIS) in the frequency range from 200 mHz to 100 kHz was performed with a Zennium electrochemical workstation (ZAHNER, Germany) in the dark with the alternate current amplitude set at 10 mV. Currentvoltage (J-V) characteristics of PSCs were measured using a Keithley 2400 digital SourceMeter controlled by a computer under a standard AM 1.5 solar simulator (Oriel 91160-1000 (300 W) Solar Simulator). Incident photon-to-current conversion efficiency (IPCE) for PSCs was recorded on the QTest Station 2000 IPCE measurement system, CROWNTECH, USA. The spacecharge-limited-current (SCLC) method was used to measure the hole mobility of HTMs using the equation: 37

Synthesis of JW6, JW7 and JW8
The synthesis routes for JW6, JW7 and JW8 are shown in Scheme 2. The intermediates of compounds 1-7 have been reported in literature reports. 34,[38][39][40][41] General procedure for the synthesis of compounds JW6, JW7 and JW8. Compounds 7a-c (0.677 mmol) were dissolved using anhydrous THF in a 100 mL two-neck round-bottom ask under N 2 . Aer the temperature dropped to 0 C, the THF solution of t-BuOK (0.880 mmol) was added dropwise, and the solution turned yellow. The reaction was kept at 0 C for 1 hour. Then, THF solution of 4 (0.564 mmol) was added slowly. The mixture was then placed at room temperature and stirred overnight. Then, saturated NH 4 Cl was added to stop the reaction and the product was extracted with dichloromethane. The combined organic layer was washed with brine and dried over anhydrous Na 2 SO 4 . The solvent was evaporated, and the remaining crude product was puried by column chromatography to obtain the desired compounds JW6, JW7 and JW8.
Characterization details for the synthesis of JW6, JW7 and JW8 are provided in ESI. †

Spectral, electrochemical and thermal stability measurements
Suitable HOMO and LUMO levels are important for HTMs to achieve hole transport in a PSC device. The HOMO levels matching the valence band energy of CH 3 NH 3 PbI 3 are suitable for fabricating efficient PSCs. In this study, the energy levels of the three HTMs were determined by spectroscopic and electrochemical measurements. As shown in Fig. 1(a), UVvisible absorptions of JW6, JW7 and JW8 were measured in lm and in dichloromethane solution. The energy gap (E 0-0 ) values of JW6, JW7 and JW8 were calculated from the onset wavelengths of the absorption spectra in solution, which were 2.92 eV, 3.01 eV and 2.85 eV, respectively. JW8 showed the smallest E 0-0 value among the three HTMs, suggesting that JW8 possesses larger p-conjugation than JW6 and JW7. This was consistent with the maximum absorption peak of JW8 displaying a red shi in comparison with that of JW6 and JW7 both in dichloromethane solution and in solid-state lm. The absorption of the studied HTMs bearing biferrocene was extended to around 450 nm. Cyclic voltammetry (CV) was used to measure the oxidation and reduction peaks of JW6, JW7 and JW8 in dichloromethane solution, and the CV curves are shown in Fig. 1(b). The HOMO levels of JW6, JW7 and JW8 were calculated from the equation E HOMO ¼ À4.7 À E ox . The corresponding E HOMO values of JW6, JW7 and JW8 were À5.40 eV, À5.41 eV and À5.42 eV, respectively. The E HOMO values of the studied HTMs were very close and slightly higher than the valence band energy of CH 3 NH 3 PbI 3 . Thus, it was easy for the new HTMs to accept holes transferred from CH 3 NH 3 PbI 3 . The LUMO levels of JW6, JW7 and JW8 were calculated from the equation E LUMO ¼ E HOMO + E 0-0 , and the corresponding E LUMO values were À2.48 eV, À2.40 eV and À2.57 eV, respectively. The higher E LUMO value of JW7 can more effectively prevent the electron transfer from CH 3 NH 3 PbI 3 to HTMs, and thus reduce charge recombination in the device. Moreover, the energy level scheme for a p-i-n cell is represented in Fig. 1(c), in which the difference in HOMO and LUMO energy levels of the three compounds can be clearly seen. The related spectral and electrochemical results are listed in Table 1.
Differential scanning calorimetry (DSC) was used to test the glass transition temperature (T g ) of JW6, JW7 and JW8. DSC curves of these new HTMs are displayed in Fig. 2. JW8 possessing 4,4 0 -methylenebis(N,N-dimethylaniline) and JW7 possessing bis(4-methoxyphenyl)methane have higher T g values (129 C and 120 C) than JW6 possessing triphenylamine (116 C). The DCS result shows JW6, JW7 and JW8 to have good stability in the amorphous state.

Theoretical calculations
The substituents have an important inuence on the electron distribution and conjugated construction of HTM molecules. Theoretical calculations on the basis of DFT at the B3LYP/6-31G(g,d) level were used to optimize the geometric structures of the new HTMs. The optimized structures of JW6, JW7 and JW8 are given in Fig. S1, † and the representative bond lengths and dihedral angles are listed in Table S1 (seen in ESI †). The frontier molecular orbitals of the three compounds are shown in Fig. 3. The highest occupied molecular orbitals (HOMO) of the three compounds are almost delocalized over the whole molecule. The lowest unoccupied molecular orbitals (LUMO) are localized in the double bond part. The LUMO of JW7 is transferred from the triphenylamine part to the (4-methoxyphenyl)methane section. As shown in Table S1, † the C-C bond lengths of ferrocenylethynyl and triphenylamine in the three compounds are the same (1.423Å), and the C-N bond lengths of this triphenylamine are similar, which are 1.419Å, 1.418Å and 1.416Å for JW6, JW7 and JW8, respectively. JW7 and JW8 have a shorter C-N bond length, suggesting a longer p-conjugated  length. Moreover, JW7 and JW8 have similar C]C bond lengths of 1.468Å and 1.467Å, respectively. The C-C bonds of double bond and diphenylmethane group for JW7 and JW8 are 1.491Å and 1.489Å, respectively. Overall, JW8 has the shortest bond length among the three HTMs. The dihedral angles of the two phenyl rings of the triphenylamine connecting ferrocenylethynyl in JW6, JW7 and JW8 are 40.9 , 39.4 and 37.9 , respectively. The dihedral angles between the double bond and the phenyl ring of diphenylmethane group in JW7 and JW8 are À26.9 and À25.2 , respectively. The data of dihedral angles also indicate that JW7 and JW8 have a more planar conjugated plane than JW6. Therefore, the results suggest that JW7 and JW8 may have a trend for faster charge transport than JW6. The device performances of the three compounds will be discussed in detail in Section 3.3.

Device performance
HTM solutions were prepared to be spin-coated for fabricating PSC devices, and two architectures of PSCs were constructed to evaluate the photovoltaic performances of the new HTMs-based cells. In the inverted planar heterojunction perovskite solar cells (p-i-n), the studied HTMs are used without any additives. The concentration of HTM solutions was 5 mg mL À1 . The p-i-n cells were based on the structure of ITO/HTM/perovskite/PCBM/ BCP/Ag. Fig. 4 shows a cross-section SEM image of the p-i-n-type cell. The structure of the device is dense and neat. The ll factor (FF) of p-i-n cells fabricated by using JW6, JW7 and JW8 is higher than that of their n-i-p cells. The PCE of p-i-n cells based on JW6, JW7 and JW8 are 10.23%, 11.43% and 10.42%, respectively. The PCE of PSCs fabricated using the standard PEDOT is 12.86%. The corresponding J-V curves of p-i-n cells are shown in Fig. 5(a). In addition, device performances of p-i-n cells display replicability and stability. The photovoltaic parameters of eight cells of p-i-n-type PSCs fabricated using JW7 are presented in Table S2. † They are kept at room temperature (25 C) and in ambient air of 30% RH without encapsulation. Hysteresis test for p-i-n type PSCs based on the new HTMs was conducted, and the results are summarized in Table S3. † Fig. S2 † exhibits the J-V plots of p-i-n type PSCs based on JW7 through reverse and forward bias at a scan rate of 0.1 V s À1 . The data of hysteresis test for p-i-n type PSCs fabricated using the standard PEDOT are also provided in Table S3 † as a reference.
Results of the incident photon-to-current conversion efficiency (IPCE) spectra of p-i-n cells fabricated using JW6, JW7 and JW8 are shown in Fig. 5(b). The three HTMs have a wide range from 450 nm to 700 nm. The difference in J SC is in accordance with that in the measured values in the order of JW7 > JW8 > JW6 (Table 2).
Furthermore, data based on the space-charge-limitedcurrent (SCLC) method was used to study the hole mobility of JW6, JW7 and JW8. Fig. 6(a) shows the tting current densityvoltage (J-V) curves. The calculated values of the hole mobility of JW6, JW7 and JW8 were 1.3 Â 10 À4 cm 2 V À1 s À1 , 4.2 Â 10 À4 cm 2 V À1 s À1 and 1.5 Â 10 À4 cm 2 V À1 s À1 . JW7 showed higher hole mobility than JW6 and JW8, indicating that different substitutes   had signicant inuence on the intermolecular charge transport of the studied HTMs. Photoluminescence (PL) measurements were recorded to study the charge extraction capability of JW6, JW7 and JW8, and those for PEDOT were also recorded as a standard. Fig. 6(b) displays the steady-state PL spectra of the CH 3 NH 3 PbI 3 perovskite lms without or with capping different HTMs. The PL band of the perovskite lm is observed to be centered at 756 nm by excitation at 500 nm. All the bilayers show a drastic quenching of PL with respect to the pristine perovskite, following the order of perovskite/JW7 > perovskite/ JW8 > perovskite/JW6. This suggests that JW7 has a more positive effect on device performances than JW6 and JW8, beneting from the higher hole mobility and hole extraction capability. 42 Electrochemical impedance spectroscopy (EIS) was performed to further understand charge recombination in PSCs fabricated using JW6, JW7 and JW8. Fig. 6(c) displays the Nyquist plots. The recombination resistance (R rec ) is represented by the large arc at low frequency. The R rec value increases in the sequence of JW8, JW7 and JW6, indicating that the device performances based on JW8 are affected by faster charge recombination. Larger R rec of JW6 and JW7 are benecial for reducing charge recombination. 37 However, the device performances based on JW6 are limited by relatively lower hole mobility, according to data of PL measurements. Therefore, JW7 with the 4,4 0 -methylenebis(N,N-dimethylaniline) substituent shows a good performance in the inverted planar heterojunction perovskite solar cells.
In addition, different concentrations of JW7 were tested in the regular mesoporous TiO 2 -based perovskite solar cells (n-i-p). The structure of the n-i-p-type cells is FTO/TiO 2 /perovskite/ HTM/Ag. The photovoltaic parameters of the representative devices based on n-i-p-type PSCs are listed in Table 3. All the n-ip cells are based on HTM solutions prepared by adding only TBP and without adding expensive additives such as LiTFSI.     7 shows the effect of different concentrations on n-i-p device performances determined by J-V measurements. When using JW7 of 30 mg mL À1 , the value of photocurrent (J SC ) drops sharply, and the highest PCE is only 2.23%. The PCE increases to 8.65% when the concentration of JW7 is reduced to 20 mg mL À1 . Furthermore, the device performances get even better when the concentration of HTM solution decreases to 10 mg mL À1 , and the PCE can reach 9.36%.

Conclusions
In this study, three triphenylamine derivatives containing ferrocene were synthesized and used as organic HTMs for fabricating efficient PSCs. The substitutes on their structures are different, which are triphenylamine for JW6, bis(4methoxyphenyl)methane for JW7 and 4,4 0 -methylenebis(N,Ndimethylaniline) for JW8. The maximum absorption wavelengths of the three compounds are around 370-380 nm and that of JW8 (378 nm) has a red shi when compared with JW6 (372 nm) and JW7 (372 nm). Theoretical calculations show that JW7 and JW8 have a more planar conjugated structure. The three HTMs display T g values beyond 110 C. SCLC results show that JW7 exhibits the highest hole mobility among the studied HTMs. In the inverted p-i-n-type of PSCs (ITO/HTM/perovskite/ PCBM/BCP/Ag), JW7 shows better photovoltaic performance than JW6 and JW8 under the same conditions, leading to a PCE of 11.43% (standard PEDOT, 12.86%). In the conventional n-i-p device of FTO/TiO 2 /perovskite/HTM/Ag, the optimal concentration of HTM is 10 mg mL À1 . The corresponding highest PCE for these n-i-p cells was 9.36%, which were fabricated using JW7 and adding TBP as the dopant. Therefore, ferrocene-containing materials have a great potential in perovskite solar cells, and there is a lot of work to be done in the development of these ferrocene-based HTMs for fabricating high-efficiency PSCs.

Conflicts of interest
There are no conicts to declare.


extfieldsofstudy: Medicine Chemistry

text:
MnOx/IrOx as Selective Oxygen Evolution Electrocatalyst in Acidic Chloride Solution

The oxygen evolution reaction (OER) and chlorine evolution reaction (CER) are electrochemical processes with high relevance to water splitting for (solar) energy conversion and industrial production of commodity chemicals, respectively. Carrying out the two reactions separately is challenging, since the catalytic intermediates are linked by scaling relations. Optimizing the efficiency of OER over CER in acidic media has proven especially difficult. In this regard, we have investigated the OER versus CER selectivity of manganese oxide (MnOx), a known OER catalyst. Thin films (∼5–20 nm) of MnOx were electrodeposited on glassy carbon-supported hydrous iridium oxide (IrOx/GC) in aqueous chloride solutions of pH ∼0.9. Using rotating ring–disk electrode voltammetry and online electrochemical mass spectrometry, it was found that deposition of MnOx onto IrOx decreases the CER selectivity of the system in the presence of 30 mM Cl– from 86% to less than 7%, making it a highly OER-selective catalyst. Detailed studies of the CER mechanism and ex-situ structure studies using SEM, TEM, and XPS suggest that the MnOx film is in fact not a catalytically active phase, but functions as a permeable overlayer that disfavors the transport of chloride ions.

S2
To prepare the IrOx/GC electrode, the IrOx particles were electroflocculated on the GC surface under rotation. A 4 mL aliquot of the bulk alkaline solution was re-acidified with 60% HClO4 down to pH ≈ 1.5. The removal of OHinduced the deprotection of the IrOx colloids, which manifested as a solution color change from purple to greyish violet. Care must be taken not to make the IrO x solution too acidic, since competing CER at low pH may interfere with the reproducibility of the deposition. CER originates from the Clwhich is present as byproduct from the Na 2 IrCl 6 hydrolysis. Deposition was then performed at a rotation rate of 600 RPM on a freshly prepared GC surface. The disk electrode was first scanned at 250 mV s -1 in range of 0.16 -1.36 V vs. Ag/AgCl, to observe initial IrO x deposition coupled to increasing OER and CER catalysis. This was followed by amperometry for 300 s at 1.255 V vs. Ag/AgCl at a potential 10 mV positive of the onset of mixed OER and CER, currents rising over time indicated further IrOx deposition. After deposition, a reflective blue film was visible on the GC surface.

Rotating ring-disk studies (RRDE) of chlorine evolution vs. MnOx deposition
RRDE measurements were done with a MSR rotator and E6 ChangeDisk RRDE tips in a PEEK shroud (Pine Research). The Luggin tip connected to the reference electrode was aligned to the center of the RRDE electrode to minimize electrical cross-talk. 5,6 The liquid phase collection factor of the ring-disk system, , was determined by studying the Fe[CN] /Fe[CN] redox couple in a solution of 10 mM K3Fe[CN]6 and 0.1 M KNO3, using the Pt ring with both a freshly prepared blank GC electrode and the IrOx/GC electrode. The value was 0.244 within 5% accuracy. The collection factor for dissolved Cl2 was also measured in the same setup, by evolving chlorine selectively on a Pt disk electrode at 1.6 V vs. RHE, well before the kinetic onset of OER. Provided that the solution pH was lower than 1, 7 the collection factor for dissolved chlorine was found to be 0.240, almost identical to .
Before RRDE experiments, the Pt ring was electropolished by scanning from -0.1 V to 1.7 V at 500 mV s -1 for 40 scans at 1500 RPM, after which the individual scans did not change. This step was vital to remove traces of IrOx that deposited on the ring during IrOx electroflocculation under rotation. 8 Hydrodynamic experiments were done at 1500 RPM by scanning the disk electrode in the range of 1.1 -1.55 V at 10 mV s -1 . The ring was kept at 0.95 V during measurement of CER rates. Presence of Mn 2+ is not expected to interfere with the Pt ring during experiments. 9,10 In between experiments, the IrOx/GC electrode was kept at 1.1 V. Ring currents were corrected for constant background S5 currents and product collection delay. The latter arises from the time needed for products formed on the disk to reach the ring, and was approximately 200 ms at 1500 RPM. Before initiating quantitative measurements, the IrOx/GC electrode was scanned 40 times in a chloride-free electrolyte between 1.3 -1.55 V (into the OER region) at 1500 RPM. This was done to ensure stable IrO x film behavior during experiments. All currents were reported without normalization to catalyst surface area, since we were purely interested in selectivity trends (which are ratios of currents) and kinetic parameters such as Tafel slopes, none of which are affected by normalization.

On-line electrochemical mass spectroscopy (OLEMS)
During OLEMS experiments, volatile reaction products were collected in situ using a 0.5 mm diameter tip with a porous PTFE membrane at a close distance (~10 μm) to the electrode surface, positioned with a micrometric screw system. 11 Mass signals were measured using an EvoLution mass spetrometer setup (ESS Ltd.) equipped with a Balzers QMS200 quadrupole (Pfeiffer). Pressure in the mass chamber was maintained lower than 10 -6 mbar using a rotary vane pump (Edwards nXDS6i) and a TMH-071P turbo molecular pump (Pfeiffer  12 In all cases, when a satisfactory MnOx coverage was reached, the experiment was discontinued by raising the working electrode while rotating, breaking electrical contact and spin-drying the surface. This procedure was employed to minimize transient MnOx dissolution in the acidic environment. Immediately after spin-drying, the electrode was rinsed with ample water and dried with compressed filtered air.

Scanning electron microscopy (SEM)
GC disks were carefully removed from the RRDE tip after deposition and glued to a SEM specimen mount using conductive silver epoxy. Scanning electron micrographs were made using a FEI Nova NanoSEM 200 equipped with a field emission electron source, operating at 10 kV beam accelerating voltage and 10 pA probe current. Images were recorded in immersion mode using a through-thelens detector, at a working distance of ~4.5 mm. EDS measurements were performed in a JSM 6010LA setup (JEOL). After recording overview images at 10 kV, the beam accelerating voltage was increased to 15 kV and elemental data were recorded from a wide variety of locations on the electrode.

Transmission electron microscopy (TEM)
GC disks were carefully removed from the RRDE tip after deposition, and the IrO x /MnO x films were then carefully scraped off the electrode surface. The films were sonicated for 30 minutes in absolute ethanol, and the suspension was dropcasted onto a Cu TEM grid. Bright-field transmission micrographs were recorded using a JEM-1400Plus apparatus (JEOL) equipped with a LaB6 filament and a 2kx2k Orius camera (Gatan), operating at 120 kV accelerating voltage. For measurements at higher resolution, a model JEM-2010 (JEOL) equipped with a LaB6 filament and a Orius 831 camera (Gatan) was used, operating at 200 kV. Selected-area diffraction patterns were analyzed using the CrysTBox software suite. 13

X-ray diffraction measurements (XRD)
GC disks were carefully removed from the RRDE tip after deposition and mounted directly in the diffractometer using a height-adjustable mount to correct for disk protrusion. X-ray diffraction spectra were recorded using a D8-Advance diffractometer (Bruker) operated in Bragg-Brentano geometry, equipped with a Co-Kα anode (λ = 1.78897 Å) and a Lynxeye position sensitive detector. Diffraction data were collected over angles ranging between 10° -100° with a step size of 0.02° and scan speed of 0.2° s -1 .

X-ray photoelectron spectroscopy (XPS)
GC disks were carefully removed from the RRDE tip after deposition and mounted directly in the spectrometer. X-ray photoelectron spectroscopy measurements were performed in a K-alpha spectrometer (Thermo Fisher Scientic) using a monochromatic Al-Kα X-ray source. The measurements were carried out at a chamber pressure of about 10 -8 mbar, a flood gun was used for charge compensation. The energy analyzer was operated with a pass energy of 200 eV and 0.25 eV energy spacing for the survey spectrum, and a pass energy of 50 eV and 0.1 eV energy spacing for the high-resolution spectrum. All binding energies were referenced to the C1s peak (284.8 ± 0.025 eV). Each spectrum reported is the statistical average of 10 measured scans. Spectral peaks were analyzed and processed using Thermo Avantage v5.903 software (Thermo Fisher Scientic). The Shirley algorithm was used to calculate background contributions. Relative atomic contributions on the surface were calculated using full width integration over the core-level signals along with tabulated atomic sensitivity factors (ASF). For the core-level Ir 4f peak deconvolution, we used a model from existing literature, excluding contributions from 4f satellite peaks. 14

Estimation of iL of MnOx deposition
The diffusion limited current of MnOx deposition at 1500 RPM was determined by means of the equation for the diffusion-limited current: where = 2 is the amount of electrons transferred in the reaction, F is Faraday's constant (96485 C/mol), is the diffusion constant of Mn 2+ in water (7.12•10 -10 m 2 s -1 ), is the species concentration [Mn 2+ ] = 0.6 mol m -3 ) and is the diffusion layer thickness, which is dependent on the rotation rate (157.08 rad/s) and can be determined via the Levich equation:

Eq. (SI 2)
The value of , the kinematic viscosity of the solution, can be estimated at 1.0•10 -6 m 2 s -1 for dilute ( < 1 M) aqueous salt solutions, yielding ≈ 140 μA.       45 V (B, black), coinciding with a rise in ring current as BER rates increase. Due to the backward scanning potential, BER rates on the ring decrease quickly after their rise. Resuming the forward direction after crossing the 1.10 V lower potential limit, the IrOx/GC electrode is MnOx-free, which is apparent from a rise in current near 1.20 V (C, black), corresponding to onset of BER. As the potential is scanned higher than 1.45 V, crossing into the second scan (A, blue), the disk current is composed of bromine evolution and the onset of OER. The ring shows significant bromine reduction current, approaching near diffusion limited BER rates on the disk.

BER (Bromine Evolution Reaction) measurement on MnOx/IrOx
There is also minor hysteresis in the ring current during scan reversal, currents decrease over time due to transient MnOx growth. In absence of an integral MnOx film, the remainder of the second scan (B and C, blue) shows simply the decrease in OER and BER. Scan 3 (orange trace) overlapped strongly with scan 2.
A more elaborate study of the effect of MnOx on BER selectivity was not pursued, since it is outside the scope of this article. The nature of bromine evolution is substantially different from CER, 15   (4) Fine, D. A. Inorg. Chem. 1964Chem. , 32, 1964Chem. -1966


extfieldsofstudy: Biology Medicine

text:
Oplopanax horridus: Phytochemistry and Pharmacological Diversity and Structure-Activity Relationship on Anticancer Effects

Oplopanax horridus, well-known as Devil's club, is probably the most important ethnobotanical to most indigenous people living in the Pacific Northwest of North America. Compared with the long history of traditional use and widespread distribution in North America, the study of O. horridus is relatively limited. In the past decade, some exciting advances have been presented on the phytochemistry and pharmacological diversity and structure-activity relationship on anticancer effects of O. horridus. To date, no systematic review has been drafted on the recent advances of O. horridus. In this review, the different phytochemicals in O. horridus are compiled, including purified compounds and volatile components. Animal and in vitro studies are also described and discussed. Especially, the potential structural-activity relationship of polyynes on anticancer effects is highlighted. This review aimed to provide comprehensive and useful information for researching O. horridus and finding potential agents in drug discovery.

Introduction
Oplopanax horridus (Sm.) Torr. & A. Gray ex Miq., wellknown as Devil's club, an ethnobotanical, exclusively originates and is distributed in northwestern North America. This understory shrub forming larger populations through layering usually grows in moist, well-drained, dense, and old-growth forests [1]. This herbal plant belongs to the genus Oplopanax, which only consists of three species, the remaining of which are O. japonicus Nakai and O. elatus (Nakai) Nakai [2]. O. elatus is mainly distributed in the temperate regions of Northern China, the south of Primorye, northern part of the Korean Peninsula, and Russia [3], while O. japonicus is endemic to central Japan [4]. The genus Oplopanax is classified to the Araliaceae family, which comprises some world-known botanicals such as Panax ginseng (Asian ginseng, Chinese or Korean ginseng), P. quinquefolius (American ginseng), and P. notoginseng (Sanqi) [5][6][7][8]. Occasionally, O. horridus is sometimes marketed as "wild armored Alaskan ginseng," "Alaskan ginseng," or "Pacific ginseng", but the marketing is now forbidden in the United States due to the misleading [2]. Such marketing relies on the presumable speculation that O. horridus share similar chemical ingredients with the herbs in Panax, but the presumption is not supported by related phytochemical investigation [4].
O. horridus has a long history of use for 34 different medical ailments by the Pacific indigenous peoples from over 38 linguistic groups [7]. The extracts of Devil's club are marketed in North America for respiratory stimulant and expectorant, rheumatoid arthritis, autoimmune conditions, eczema, type II diabetes, external infections, and internal infections [7]. The Pacific native tribes also use O. horridus for spiritual stimulant, while Shaman use it in their religion ceremonial practices. Table 1 summarizes that different part of O. horridus is used for many various ailments by the indigenous people. It implies that the main phytochemicals in different parts of O. horridus are significantly varied.

Ethnobotanical and Ethnopharmacology
O. horridus is distributed from Alaska along the Pacific Coast down to Oregon, Idaho, and Montana in the south and east to the southwestern Yukon Territory, while some isolated populations grow around Michigan and the islands in Lake Superior ( Figure 1) [7,9]. O. horridus generally is from 1 to 1.5 m tall, while it can grow to 3 to 5 m in some undisturbed moist rainforest. The spines appear around the stems and along the upper and lower surfaces of its leaves, which are palmately lobed with 5-13 lobes, 20 to 40 cm across, and are spirally located on the stems (up to 3 cm diameter). The flowers are blooming in dense umbels from 10 to 20 cm diameter with five greenish-white petals. The fruit is a small red drupe with 4 to 7 mm diameter. The root without spines is similar to the stem [9]. The plant grows and reproduces slowly and take many years to reach seed bearing maturity, and it is very sensitive to human impact [10]. and spitting the crude herb on the wound as an emergency analgesic and antiseptic [10]. The infusion of inner bark of O. horridus was described as a possible treatment for cancer by indigenous peoples in North America [7]. Although formal documentation of its traditional use for cancer is lacking, O. horridus extracts and its compounds exhibited the anticancer activities in preclinical investigations [2,4].

Phytochemistry
The main chemical constituents of O. horridus are polyynes (polyacetylenes), phenylpropanoids (aglycones and glycosides), lignan glycosides, triterpenoids, sesquiterpenes, and volatile compounds [4]. Within the different structural skeletons of these groups, a variety of analogues are presented in the aerial and underground parts of the botanical. Generally, the secondary metabolites in O. horridus are consistent with the patterns of chemical constituents from the genus Oplopanax and the family Araliaceae. Polyynes have been mostly reported with high contents in both the stem and the root of O. horridus as potential anticancer and antimycobacterial (antituberculosis) natural products. Due to the limited number of analytical chemistry investigations that have been done, only six polyynes have thus far been quantified in the root of O. horridus [14,15]. Phenylpropanoids and lignan glycosides are the other two main natural products from the genus Oplopanax. Sesquiterpenes and volatile compounds have also been extracted from the root of this herb. For this species, the chemical profile of the polyynes of the root may be useful for herbal identification since they are very different from the other species in this genus, O. japonicus and O. elatus.

Polyynes (Polyacetylenes).
Polyynes, also known as polyacetylenes, possess a long chain of carbon atoms with alternating double and triple bonds between them, which occur in natural products containing more than two acetylene groups. Meanwhile, polyynes comprising two to four acetylene groups are usually found in higher plants, most of which contain conjugated diyne in the highly unsaturated lipid chains [16]. These highly unsaturated hydrophobic compounds are generated in the Araliaceae family, which have a high concentration in the roots and a small content in the stem barks. The polyynes which are unstable and oxidized in dried plant material, contain seventeen or eighteen carbons (C17 or C18) in the skeleton chain, and are mostly found in the Araliaceae.
Although no evidence is found that O. horridus is used to cure cancer in North America in the long history, the extracts and polyynes from O. horridus exhibited their anticancer activities in recent pharmacological research. The extracts mainly containing polyynes from O. horridus root bark showed effective in the inhibition of the proliferation of several ovarian, breast, lung, and colorectal cancer cell lines [20,21]. The mechanisms of polyynes on anticancer activities are still not well known. To the tested polyynes, Falcarindiol and Oplopantriol A showed the strongest inhibition on the growth of all the examined cancer cell lines [22,23].

Phenylpropanoids (Aglycones and Glycosides).
Phenylpropanoids are metabolized by plants from the amino acids phenylalanine and tyrosine. The basic chemical structure of phenylpropanoid consists of the aromatic phenyl group and the three-carbon propene tail of cinnamic acid. Phenylpropanoids are found commonly in the plant kingdom, where they play a vital role as essential components in biosynthesizing polymers, providing protection from ultraviolet light, defending against herbivores and pathogens, and mediating plant-pollinator interactions. Phenylpropanoids including aglycones and glycosides were also obtained from O. horridus [24]. As phenolic compounds, phenylpropanoids   determined by any analytical method. Therefore, the contents of the phenylpropanoids in any part of O. horridus are still unknown. These phenylpropanoids showed no cytotoxic effects against human cancer cell lines (HCT-116, HT-29, MDA-231, and MCF-7) by MTT method [26]. Phenylpropanoids have not been found in other parts of O. horridus, while some phenylpropanoids are recently found in the root of O. elatus [28].

Lignan Glycosides.
The lignans are a large group of natural products found in plants, which have also been obtained from the family Araliaceae. Usually, plant lignans are derived from phenylpropanoids via dimerization of substituted cinnamic alcohols, which is catalysed by oxidative enzymes and controlled by dirigent proteins. Due to the rarely investigation on the hydrophobic constituents from O. horridus, no lignan aglycone has been found in O. horridus. Meanwhile, lignan glycosides are firstly purified and identified from the hydrophilic constituents of the root bark of O. horridus [25,27].
3.6. Volatile Compounds. The volatile oil from O. horridus is regarded to be responsible for some clinical uses of the title plant. Volatile oils from natural medicines are very complicated, and volatile compounds could not be easily purified and obtained from volatile oil by modern chromatographic techniques due to their disadvantages such as lower boiling point, lower polarity, and thermal degradation. Therefore, most volatile compounds are identified before by GC/MS. Volatile oils have been extracted from stem and root of O. horridus.
Shao et al. used a supercritical fluid extraction method to extract the volatile oil from the root bark of O. horridus with a yield of 1.15%, which was much more than the yield of 0.22% when the oil was extracted by the steam distillation method. Then, the volatile oil was subsequently analyzed by GC/MS (Table 2) [32,33]. Forty-eight volatile compounds were identified by GC/MS analysis and, among all the detectable constituents, (S, E)-nerolidol (52.5%) was the compound with highest content in the volatile oil, followed by -cadinol (21.6%) and bicyclogermacrene (4.5%). (S, E)-Nerolidol and -cadinol had been purified as simple compounds from the essential oil and their structures were identified by additional spectroscopic techniques. By comparison with the MS data from the Agilent Chemstation the library, one more polyyne, S-falcarinol (3.6%), was also detected and obtained from the essential oil by chromatographic separation. Except for some very common volatile compounds, e.g., -pinene, -phellandrene, linalool, 1,3,5-undecatriene, and 1,3,5,8-undecatetraene; most of the constituents identified in the essential oil were sesquiterpenes and oxygenated sesquiterpenes. Some minor constituents were not identified by GC/MS.

Biological Activities
Different parts of O. horridus are used to help cope with verified illnesses from type II diabetes to cancer problems by indigenous people, but the pertinent pharmacological researches are very limited. Compared to few biological activity report of the leaves, the extracts of the stem and berries have only been screened for their antiproliferation effects of four human cancer cell lines (SW-480, HCT-116, HT-29, MCF-7, and NSCLC) [19]. Meanwhile, the root has been researched on its antibacterial, antifungal, antidiabetes, and anticancer effects [2,34]. In the past decade, although no record was found that any part of O. horridus was used to cure cancer in the long history, the extracts and compounds from the root of O. horridus exhibited their anticancer activities in recent investigations [2,4].

Antibacterial.
The extracts and fractions from the root of O. horridus showed antibacterial activity related with antimycobacterial, the bacteria of which may cause leprosy and tuberculosis in humans [35][36][37]. The results showed that the ingredients of O. horridus displayed synergistic enhancement on antituberculosis effect [38]. From a methanol extract of the inner bark of O. horridus exhibited antibacterial activity, five polyynes, -, , including falcarinol, falcarindiol, oplopandiol, oplopandiol acetate, and (Z)-9,17octadecadiene-12,14-diyne-1,11,16-triol 1-acetate, are purified and identified. Specifically, falcarindiol and oplopandiol were the main positive antimycobacterial components from the extract [17]. Additionally, all the obtained polyynes displayed potential ability to inhibit the proliferation of M. tuberculosis, M. avium at 10 g/disk in a disk diffusion assay, as well as two Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, two Gram-negative bacteria, Escherichia coli DC2 and Pseudomonas aeruginosa Z61, and the yeast Candida albicans. Among them, falcarindiol has been proved to possess the strongest antibacterial activities [17].

Antifungal.
The methanol extract of O. horridus inner bark was screened for antifungal activity against 9 fungal species, i.e., Aspergillus flavus, Aspergilfus fumigatus, Candida albicans, Fusarium tricuictum, Microsporum cooker, Microsporum gypseum, Saccharomyces cerevisiae, Trichoderma viridae, and Trichophyton mentagrophytes [39,40]. The extract was demonstrated antifungal activity against all the fungal strains assayed except A. flavus. The extract had only slight activity against A. fumigatus, C. albicans, F. tricuictum, S. cerevisiae, and T. viridae, but it had greater inhibition against M. gypseum. With the assayed fungi, the extract showed the greatest significant antifungal activity on M. cooker and T. mentagrophytes [39]. However, the   [41,42]. Without any data, it was claimed that O. horridus, as a pancreatic tonic, is regarded to decrease blood sugar levels by improve the efficiency of insulin [41]. Therefore, it should be cautiously used for diabetes due to the perspective risk and uncertainty. In preclinical research on O. horridus for adult diabetes, a white precipitate isolated from root bark of O. horridus showed a slightly hypoglycemic effect in lab hares [43]. Inconsistently, the O. horridus tea at a certain dosage exhibited no significant hypoglycemic effects in a primary study [44]. Three new phenolic glycosides obtained from the root bark of O. horridus, oplopanpheside A-C, displayed negative activity for their -glucosidase inhibition (IC 50 >50 M, respectively) [26]. Unambiguously, more studies are requested in concerning its antidiabetic effects.

Anticancer Effect.
The infusion of inner bark of O. horridus was described as a possible treatment for cancer by indigenous linguistic people including Alutiiq, Gitxsan, Haida, Tlingit, and Tsimshian [7]. To date, O. horridus has not been reported to have anticancer effects on human bodies, and no human clinical studies have been conducted on this herb. The extracts mainly containing polyynes from the root bark of O. horridus show anticancer effects on several colorectal, breast, lung, ovarian, pancreatic and acute myeloid leukemia cancer cell lfnes, and animal models [4,45,46].

Colorectal Cancer. The different extracts from
Oplopanax root, stem, berry, root bark, and their fractions were investigated in vitro for their potential antiproliferative effects on human HCT-116, HT-29, and SW-480 colorectal cancer cell lines [19][20][21]47]. The results showed that the stem, root, root bark extracts, and lipophilic fractions of root bark possessed potent antiproliferative effects. The observation of the cell cycle distribution suggested that G2/M phase is arrested by the extracts. However, the hydrophilic fractions had much weaker effects on the apoptotic cells [20].
Five polyynes were isolated and evaluated as the bioactive compounds from hydrophobic fractions [47]. Among these polyynes, FAD and OPT showed significant potent effects, and the primary structure-activity analysis suggested that these anticancer activities are related to the ethylenic bonds and acylations in the structures [48,49]. Firefly luciferasetagged HCT-116 cells were inoculated into the flanks of athymic nude mice used as the animal model to evaluate the in vivo antitumor potential of FAD and OPT from O. horridus [48]. The results showed that the FAD and OPT treatment groups exhibit significantly decreased xenogeny imaging signal intensities when compared with the control group. Quantitative analysis revealed that the FAD and OPT significantly inhibited xenograft tumor growth after the administration of FAD and OPT [22,23]. A rat small intestine epithelial cell line, IEC-6, is used to evaluate the safety of FAD and OPT. At concentrations of 1-20 M, FAD and OPT do not inhibit the IEC-6 cell growth. In contrast, human HCT-116 and HT-29 colorectal cancer cell growth was significantly inhibited at 15 M of FAD and OPT [23,49]. Further study showed that FAD-induced cell death was mediated by the induction of endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR). The FADinduced ER stress and apoptosis was correlated with the accumulation of ubiquitinated proteins, suggesting that FAD functions, at least in part, by interfering with proteasome function, leading to the accumulation of unfolded protein and induction of ER stress [23].
In another study, OPT significantly suppressed malignant cells in both concentration-and time-dependent manner. The IC 50 was approximately 5 M for HCT-116 and 7 M for SW-480 cells. OPT significantly induced apoptosis and arrested the cell cycle at the G2/M phase. The results showed that OPT significantly upregulated the expression of a cluster of genes, especially the tumor necrosis factor receptor family and the caspase family. The data suggested that the tumor necrosis factor-related apoptotic pathway played a key role in OPTinduced apoptosis [49].
The OPT-induced cancer cell death was also mediated by excessive ER stress. Decreasing the level of ER stress either by inactivating components of the UPR pathway or by expressing the ER chaperone protein GRP78 decreased OPT-induced cell death. OPT induced the accumulation of ubiquitinated proteins and the stabilization of unstable proteins, suggesting that OPT functions, at least in part, function by interfering with the ubiquitin/proteasome pathway [22].

Acute Myeloid Leukemia (AML). Male and female transgenic
C57BL/6J-Foxp3-RFP mice (C57BL/6-Foxp3tm1Flv/J) were employed for in vivo anti-AML. After one week following engraftment, the 70% ethanol extract of Oplopanax root was diluted into the drinking water at a final concentration of 20 g/mL. The survival of both male and female mice was significantly increased upon the inclusion of the extract in the drinking water [45]. In addition, the extract decreased the Tregs and increased CD4 + T cells and the ratio of CD8 + T cells to Tregs. These changes are indicative of a responsive immune system correlated as expected with an increase in survival [45].
The 70% ethanol extract was assessed on AML cell line viability and to study the regulation of tyrosine phosphorylation and cysteine oxidation. The root extract displayed better in vitro anti-AML efficacy in addition to a noted anti-tyrosine kinase activity. The extract decreased the viability of murine C1498 cells and human U937, HL-60/VCR, and KG-1 cells with differential effects. In addition, the effect of the extract compared with nerolidol (a major essential oil component of O. horridus) yielded a better anti-AML activity [45].

Breast Cancer.
Effects of the extracts and polyynes have also been evaluated using MCF-7 and MDA-MB-231 human breast cancer cell lines [19,21,47]. The IC 50 of the total extract, 50, 70, and 100% ethanol fractions on MCF-7 cells, were 248.4, 123.1, 44.0, and 31.5 g/mL, respectively [47]. The 100% ethanol fraction, which possessed the most potent antiproliferative activity, showed the strongest apoptotic induction activity [19]. Additionally, three phenolic glycosides isolated from the hydrophilic fraction, oplopanphesides A, B, and C, showed no cytotoxic effects on MDA-MB-231 and MCF-7 cell lines [26]. Further, when the MCF-7 cells were treated with 30 g/mL of the total extract and fractions, the total extract increased the percentage of cells in the G 1 -phase to 49% and the decreased S phase to 6.2% [21].

Lung
Cancer. The antiproliferative effects of nonsmall cell lung cancer (NSCLC) cells were evaluated. The IC 50 of the extract, 50, 70, and 100% ethanol fractions for antiproliferation on NSCLC cells, were 125.3, 271.1, 17.6, and 23.2 g/mL, respectively [19]. In addition, the extracts from the stem and berry were evaluated. The stem extract had potent antiproliferative effects at a low concentration of 0.1 mg/mL compared to 1 mg/mL for the berry [21].

Ovarian
Cancer. An ovarian cancer (Ovcar 10 threedimensional [3D]) model was utilized to evaluate the antiproliferation activity of 75% ethanol extract and its active compound, alone and in combination. Ovcar 10 cells formed compact 3D spheroids after five days of culture in a rotary culture system [50]. The 3D spheroids were significantly more resistant to killing by the extract when compared to 2D cells. A number of apoptosis-related genes were differentially expressed in these cells. In 3D spheroids, the proportion of cells in the G2/M phase was slightly increased and the S phase was slightly decreased when compared to 2D cells [50].

Pancreatic
Cancer. The 70% ethanol extract was investigated on pancreatic endocrine HP62 and pancreatic ductal carcinoma PANC-1 and BxPC-3 cells. The extract significantly inhibited the proliferation of HP62 at low IC 50 . Apoptosis focused antibody array profile indicated upregulation of cytochrome C, claspin, cIAP-2 and HTRA2/Omi apoptosisrelated markers, suggesting that the effect was via targeting the intrinsic mitochondrial apoptosis pathway [51].
The extract was also assessed for its effect on human pancreatic cancer PANC-1 3D spheroids and 2D monolayer cells. PANC-1 3D spheroids were significantly more resistant to killing by this extract with IC 50 level closer to that observed in vivo. The extract also significantly enhanced the antiproliferation activity of the antineoplastic medications cisplatin (CDDP) and gemcitabine (GEM). The bioactive compound, identified as a polyyne, showed strong antiproliferation activities. Cell cycle analysis showed that the proportion of cells in S phase was increased and in G2/M phase was reduced in 3D spheroids when compared with 2D cells [52].

Length of Carbon
Chain. The structure-activity relationship of carbon chain in polyynes with their anticancer potential is summarized in Table 3. Anticancer activities  decrease with the increase of the length of carbon chain in the main chemical structural skeleton of polyynes. To date, hundreds of polyynes have been isolated from bacterial, fungi, microorganisms, marine invertebrates, and high plants, and most naturally occurring polyynes feature a long lipid chain covering from 10 to 42 carbons in their chemical structural skeleton [16,53,54]. Among them, C 17 and C 18 -polyynes were predominantly reported for their anticancer effects [55][56][57][58]. In the tested cancer lines, the antiproliferation effects of polyyne displayed stronger effects than and , while polyyne exhibited greater activities than and [48,59]. Among these polyynes, (FAD) shows the strongest anticancer activity, suggesting that FAD is a candidate for chemical modification [60][61][62]. Table 3, (R)-falcarinol, a C 17polyyne, is obtained from some other plants, and it has been demonstrated to show antiproliferation effects on several cancer cell lines [63][64][65][66][67]. However, biological study has not been conducted on its derivative, cis-9-heptadecene-4,6diyne-8-ol, which becomes an easier volatile compound when its terminal double bond is transferred to be single bond [68]. Regarding the chemical structures of these polyynes, they could be divided into three pairs grouped by their terminal bond moieties, i.e., vs. ; vs. ; and vs. . With regard to their anticancer effects, polyyne , , and showed greater potent activity, suggesting that the terminal ethenyl group improved anticancer activity [48,59]. Recently, it is reported that the pharmacokinetic parameters between and had significant differences. Compared with , the terminal ethenyl group made easier transformed into other metabolites in vivo [69]. It has been demonstrated that compound could effectively join in chemical carcinogen detoxification by selectively mediating Phase II drug metabolism enzymes and quinone oxidoreductase [70]. Therefore, further studies should be employed to investigate the relationship between its terminal ethenyl group and anticancer behavior.

Hydroxyl Group.
Since polar compounds interact with phospholipid substances in the hydrophilic domain of cell membrane, the entrance orientation of polyynes into membranes is affected by the number and location of alcohol hydroxyl groups [71]. The number and location of hydroxyl groups in polyynes influenced its anticancer activity [72,73]. In the natural polyynes, if the hydroxyl group at C-1 was substituted with an acetyl group, the antiproliferative effect of polyyne was decreased, but if the hydroxyl group at C-11 or C-16 was acetylated, the antiproliferative activity would be significantly suppressed [59]. The anticancer activities of polyyne , , , and have been systematically compared. Oplopantriol A ( ) showed the strongest antiproliferative effects on selected colorectal cancer cell lines and greater inhibition of tumor growth in vivo [22,49]. Among the four polyynes, oplopantriol A can be considered to be a prochemical.
In order to investigate the contribution of hydroxyl groups to the antiproliferation on cancer cells, sixteen more acetylated derivatives have been synthesized for the evaluation of potential anticancer activities. The polyynes do not have any inhibitory effects of the adopted cancer cells if all the hydroxyl groups of the polyynes were acetylated [59]. However, compared to hydroxyl group at C-1, the terminal ethenyl group contribute more significance for maintaining anticancer potential. For example, compound has 3 to 5-fold relatively stronger antiproliferative effects than compound , while compound possesses 1 to 3-fold relatively greater than compound [48]. The elimination of hydroxyl groups of polyynes will yield acetylene alkanes, which have not been subjected to anticancer research.

Summary and Perspectives
O. horridus, well-known as Devil's club, is probably the most important ethnobotanical to most indigenous people living in the Pacific Northwest of North America. Different part of O. horridus has a long history to be used for ailments by local people as traditional herbal medicines. In this review, the phytochemicals mainly including polyynes, triterpenoids, sesquiterpenes, diterpenoid, lignans, and phenylpropanoids from different part of O. horridus have been compiled. To date, approximately 47 compounds have been purified from O. horridus, and most of them are discovered for the first time from this genus. However, phytochemistry studies are relatively limited on each part of O. horridus except its root.
Polyynes identified from this herb exhibit pharmacological diversity. Especially, though this botanical has not been reported to have anticancer effects in human clinical studies, polyynes from O. horridus showed effects against colorectal cancer, breast cancer, lung cancer, ovarian cancer, pancreatic cancer, and acute myeloid leukemia in human cancer cell lines and different animal models. Regarding the anticancer effects and mechanisms of polyynes, it is pertinent to several molecular mechanisms and various signaling pathways. Because the bioavailability and metabolism of polyynes are critical important, their plasma concentrations that maybe significantly affect its biological activities in vivo are unknown. Moreover, the pharmacokinetic studies are blank to these polyynes except a few reported pharmacokinetic parameters of facarindiol and oplopandiol in rat [69]. Therefore, in vivo preclinical models are essential and vital to evaluate and predict the clinical function of polyynes.
We propose that the length of lipid chain, terminal ethenyl group, number of hydroxyl groups, and stereoselectivity in polyynes affect their anticancer activity. These relationships could benefit chemical modification of polyynes for discovery of bioactive molecules. Due to the stability of polyynes, C 17 -polyynes are most researched for their anticancer activities [61]. Our former experiments showed that acetylation of polyynes decreased their activities, but cancer chemopreventive potential may be enhanced by employing other chemical functional groups into polyynes. Although different stereoisomers of polyynes could be synthesized, their potential anticancer effects have not been quantitatively compared. Further investigations are needed to develop novel anticancer candidate in drug discovery.

Conflicts of Interest
All the authors declare that they have no conflicts of interest regarding funding supports in this manuscript.