New ent-clerodane and abietane diterpenoids from the roots of Kenyan croton megalocarpoides Friis & M. G. Gilbert

Abstract

The roots of the endangered medicinal plant Croton megalocarpoides collected in Kenya were investigated and twenty-two compounds isolated. Among them were twelve new ent-clerodane (1–12) and a new abietane (13) diterpenoids, alongside the known crotocorylifuran (4 a), two known abietane and four known ent-trachylobane diterpenoids, and the triterpenoids, lupeol and acetyl aleurotolic acid. The structures of the compounds were determined using NMR, HRMS and ECD. The isolated compounds were evaluated against a series of microorganisms (fungal and bacteria) and also against Plasmodium falciparum, however no activity was observed.

# Key words Croton megalocarpoides - Euphorbiaceae - abietane - ent-clerodane - ent-trachylobane - diterpenoids - electronic circular dichroism