BACKGROUND: The extract of  Adenostemma lavenia  (L.) O. Kuntze leaves has anti-inflammatory activities and is used as a folk medicine to treat patients with hepatitis and pneumonia in China and Taiwan. The diterpenoid  ent -11α-hydroxy-15-oxo-kaur-16-en-19-oic acid (11αOH-KA) is the major ingredient in the extract and has wide-spectrum biological activities, such as antitumor and antimelanogenic activities, as well as anti-inflammatory activity. However, the physical and biological properties of this compound as an antioxidant or antiaging agent have not been reported yet. METHODS: In addition to in vitro assays, we monitored antioxidative and antiaging signals in  Schizosaccharomyces pombe  (yeast) and mouse melanoma B16F10 cells. RESULTS:  A. lavenia  water and chloroform fractions showed antioxidant properties in vitro. The  A. lavenia  extracts and 11αOH-KA conferred resistance to H 2 O 2  to  S. pombe  and B16F10 cells and extended the yeast lifespan in a concentration-dependent manner. These materials maintained the yeast mitochondrial activity, even in a high-glucose medium, and induced an antioxidant gene program, the transcriptional factor  pap1  +  and its downstream  ctt1  + . Accordingly, 11αOH-KA activated the antioxidative transcription factor NF-E2-related factor 2, NRF2, the mammalian ortholog of  pap1  + , in B16F10 cells, which was accompanied by enhanced hemeoxygenase expression levels. These results suggest that 11αOH-KA and  A. lavenia  extracts may protect yeast and mammalian cells from oxidative stress and aging. Finally, we hope that these materials could be helpful in treating COVID-19 patients, because  A. lavenia  extracts and NRF2 activators have been reported to alleviate the symptoms of pneumonia in model animals.