 HxA3 is extremely unstable and HxB3 is moderately unstable, rapidly decomposing to their tri-hydroxy products, for example, during isolation procedures that use an even mildly acidic methods; they are also rapidly metabolized enzymatically in cells to these same tri-hydroxy products, termed trioxilins (TrX's) or trihydroxyeicoxatrienoic acids (THETA's); HxA3 is converted to 8,11,12-trihydroxy-5"Z",9"E",14"Z"-eicosatrienoic acid (trioxilin A3 or TrXA3) while TxB3 is converted to 10,11,12-trihydroxy-5"Z",8"Z",14"Z"-eicosatrienoic acid (trioxilin B3 or TrXB3).A third trihydroxy acid, 8,9,12-trihydroxy-5"Z",10"E",14"Z" eicosatrienoic acid (trioxilin C3 or TrXC3), has been detected in rabbit and mouse aorta tissue incubated with arachidonic acid.The metabolism of HxA3 to TrXA3 and HXB3 to TrX is accomplished by soluble epoxide hydrolase in mouse liver; since it is widely distributed in various tissues of various mammalian species, including humans, soluble epoxide hydrolase may be the principal enzyme responsible for metabolizing these and perhaps other hepoxilin compounds.