Fused Tricyclic Naphthalene Lactones and a Xanthone from Ventilago maingayi and their Anti-HIV-1 Activity

Three previously undescribed compounds, including two fused tricyclic naphthalene lactones (ventilaganones A and B, 1: and 2: ) and a xanthone (ventilagoxanthone, 3: ), along with eight known compounds (4: -11: ), were isolated from the bark of Ventilago maingayi. Their structures were elucidated by extensive analysis of their spectroscopic data and by comparison with those of related compounds reported in the literature. The absolute configuration of ventilaganone A (1: ) was established by single-crystal X-ray analysis. Anti-HIV-1 activity of the isolated compounds was evaluated with a reverse transcriptase (RT) assay and a syncytium reduction assay using the ^ΔTat/RevMC99 virus in the 1A2 cell line. Compounds 1, 2, 4, 5: , and 8-11: showed inhibitory activity against syncytium formation, while most compounds were found to be inactive in the reverse transcriptase assay.