In Vitro Action of ent-Manoyl Oxides against Leishmania donovani

Several ent-manoyl oxides obtained from natural products through chemical and microbiological procedures were tested in vitro as inhibitors of the growth of the promastigote and amastigote forms of Leishmania donovani. Compounds 3, 6, 7, and 15 showed significant antileishmanial activity. (3S)-ent-3β-Acetoxy-12-oxo-8α,13-epoxylabda-9,14-diene (15), whose semisynthesis is described, totally inhibited the promastigote forms of L. donovani at a concentration of 100 mg/mL after 24 h of incubation. Functionalization of this series of compounds plays an important role in the antileishmanial activity observed.