Identification of ent-16 beta,17-dihydroxykauran-19-oic acid as an anti-HIV principle and isolation of the new diterpenoids annosquamosins A and B from Annona squamosa

Phytochemical analysis of the fruits of Annona squamosa yielded 12 known kaurane derivatives (1-11, 13) and two new kaurane diterpenoids, which have been named annosquamosin A (16 beta-hydroxy-17-acetoxy-ent-kauran-19-al) (12) and annosquamosin B (19-nor-ent-kaurane-4a alpha,16 beta, 17-triol) (14). The structures of the new compounds were established by spectral analyses and chemical evidence. Among these 14 compounds, 16 beta,17-dihydroxy-ent-kauran-19-oic acid (2) showed significant activity against HIV replication in H9 lymphocyte cells with an EC(50) value of 0.8 mu g/mL (therapeutic index >5).