Helicterins A—F, Six New Dimeric (7.5′,8.2′)-Neolignans from the Indonesian Medicinal Plant Helicteres isora.

During a chemical study of Indonesian medicinal plants, we examined the constituents of fruits of Helicteres isora L. (Sterculiaceae), one of the famous Jamu medicines. From a H2O extract of the fruits, we isolated six new neolignans, the helicterins A – F (1 – 6), and elucidated their structures by spectral analyses. Helicterins A – F (1 – 6) are dimeric (7.5′,8.2′)-neolignans with a bicyclo[2.2.2]octene C-framework, and showed mild inhibitory activity against reverse transcriptase from avian myeloblastosis virus.