Cytotoxic and anti-HIV-1 activities of triterpenoids and flavonoids isolated from leaves and twigs of Gardenia sessiliflora

A new cycloartane triterpenoid, sessiliflorin (1), together with two new flavanones, 5,3′,5′-trihydroxy-6,7,4′-trimethoxyflavanone (10) and 5-hydroxy-6,7,3′,4′,5′-pentamethoxyflavanone (11) were isolated from a methanol extract of leaves and twigs of Gardenia sessiliflora. In addition, the known cycloartane triterpenoids 2–9 and flavonoids 12–21 were also obtained from the same source. All structures were determined based on their spectroscopic data. Most of the tested compounds including the new compounds, 1, 10, and 11 showed anti-HIV-1 activity in the syncytium reduction assay with EC₅₀ values of <8.02‒171.61 μM and SI values of 1.12–9.72 except compound 7 which was found toxic. In the anti-HIV-1 RT assay, compound 5, 10, 13, and 14 displayed weak activities with 30.00–46.40% inhibition at 200 μg/mL, while 16 showed moderate activity with 52.50% inhibition at 200 μg/mL. For cytotoxic assay, 7 displayed cytotoxic activity in all tested cell lines except A549 cell line with IC₅₀ values of 0.6–4.8 μM, whereas 3–5 and 14 were found active in P-388 cell line with IC₅₀ values of 1.2–7.5 μM. However, compounds 5 and 7 were also found toxic to HEK 293 cell line.