(+-)5(6)-DiHET lactone (Item No. 51212) is a 1,5 cyclic ester derived from (+-)5(6)-DiHET (Item No. 51211), which, in turn, is a potential derivative of epoxidation of arachidonic acid (Item No. 90010) at the a-5 double bond. (+-)4(5)-DiHDPA lactone is a derivative of docosahexaenoic acid (DHA; Item No. 90310) that is analogous to (+-)5(6)-DiHET lactone. It is the 1,4 cyclic ester derived from (+-)4(5)-DiHDPA, which is produced by epoxidation of DHA at the a-4 double bond. Its biological activity is unknown.