Anti-HIV-1 diterpenoids from leaves and twigs of Polyalthia sclerophylla.

Bioassay-guided fractionation and purification of the anti-HIV-1-active MeOH extract from the leaves and twigs of Polyalthia sclerophylla led to the isolation of two new compounds, ENT-kaur-sclerodimer ( 1) and cyclotucanol 3-palmitate ( 2), along with the known ENT-kaur-16-en-19-oic acid ( 3), 15 beta-hydroxy- ENT-kaur-16-en-19-oic acid ( 4), 15 beta-acetoxy- ENT-kaur-16-en-19-oic acid ( 5), 15-oxo- ENT-kaur-16-en-19-oic acid ( 6), 16 alpha,17-dihydroxy- ENT-kauran-19-oic acid ( 7), 16 alpha-hydroxy- ENT-kauran-19-oic acid (xylopic acid) ( 8), a pseudodimer (15 alpha-hydroxy- ENT-kaur-16-en-19-oic acid/17-hydroxy- ENT-kaur-15-en-19-oic acid) ( 9), ermanin, nicotiflorin, and allantoin. Among these isolates, compound 3 was the most active in both anti-syncytium (EC (50) 13.7 microg/mL and selectivity index 3.1) and HIV-1 reverse transcriptase (IC (50) 34.1 microg/mL) assays.