Constituents of Croton megalocarpus with Potential Anti-HIV Activity.

Reported herein is an anti-HIV monochlorinated compound, 1β-acetoxy-3β-chloro-5α,6α-dihydroxycrotocascarin L (), of the rare crotofolane diterpenoid class. Compound , a suspected artifact of extraction, along with the previously undescribed 11β-acetoxycrotocascarin L () and a known compound, crotocascarin K (), were isolated from the bark of , a Kenyan oil-producing seed crop. Compounds and inhibited HIV-1 replication with IC values of 28 and 5.5 nM, respectively. Furthermore, both compounds lacked cytotoxicity toward MT-4 cells and FM-55-M1 cells at concentrations of up to 50 μM. Compounds and were both found to inhibit HIV-1 protease.