Jatrophane diterpenes from the latex of Euphorbia obtusifolia with inhibitory activity on the mammalian mitochondrial respiratory chain.

Seven diterpenes isolated of the latex of the Euphorbia obtusifolia were evaluated as inhibitors of the NADH oxidase activity in submitochondrial particles from bovine heart. Compound 2, 2,3,5,7,8,9,15-heptahydroxyjatropha-6(17),11-diene-14-one 8,9-diacetate 7-isobutyrate 2,3-bis(2-methylbutyrate), was the most potent inhibitor with an inhibitory concentration (IC 50 ) value of 5.1 +/- 0.2 microM. In the present study, some structure-activity trends are suggested for the inhibitory activity of these natural products on the mammalian mitochondrial respiratory chain.