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 ( 1 ), of the rare crotofolane diterpenoid class. Compound 1 , a suspected artifact of extraction, along with the previously undescribed 11β-acetoxycrotocascarin L ( 2 ) and a known compound, crotocascarin K ( 3 ), were isolated from the bark of Croton megalocarpus , a Kenyan oil-producing seed crop. Compounds 1 and 3 inhibited HIV-1 replication with IC 50 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 1 and 3 were both found to inhibit HIV-1 protease.