Anti-HIV-1 activities and chemical constituents from leaves and twigs of santisukia pagetii (Bignoniaceae)

The first phytochemical investigation of the leaves and twigs of Santisukia pagetii (Bignoniaceae) using a bioassay-guided fractionation led to the isolation and identification of seventeen known compounds, including four triterpenoids, 3-O-acetylpomolic acid (1), ursolic acid (2), 3-O-acetylursolic acid (3) and siaresinolic acid (4), three iridoid glycosides, specioside (5), verminoside (6) and ambiguuside (7), three flavonoid glycosides, luteolin-7-O-neohesperidoside (8), apigenin-7-O-neohesperidoside (9) and isoquercitrin (10), two phenolic compounds, p-coumaric acid (11) and caffeic acid (12), one monoterpenoid, (6S)-menthiafolic acid (13), together with α-D-glucose (14), β-D-maltose (15), β-sitosterol 3-O-β-D-glucopyranoside (16), a mixture of β-sitosterol (17A) and stigmasterol (17B). Compounds 1-13 were isolated from Santisukia genus for the first time. In addition, compounds 1-7, 9 and 10 were found to be active against HIV-1 in anti-syncytium assay, while only compounds 1 and 3 were found to be active (84.4% and 87.2% inhibition at 200 μg/mL, with IC₅₀ values of 290.96 and 210.34 μM, respectively) against HIV-1 reverse transcriptase. Moreover, anti-HIV-1 activities of compounds 1, 3-8, and 13 were reported for the first time.