Authors: Hsu Y.M., Wu T.Y., Du Y.C., El-Shazly M., Beerhues L., Thang T.D., Van Luu H., Hwang T.L., Chang F.R., Wu Y.C.

Abstract: The phytochemical investigation of the methanolic extract of Uvaria flexuosa (Annonaceae) leaves led to the isolation of seven compounds including, 3-methyl-4,5-dihydro-oxepine (flexuvaroxepine A), four polyoxygenated seco-cyclohexene (flexuvarin A–D) and two polyoxygenated cyclohexene (flexuvarol A–B) derivatives, together with four known flavones. The structures of the isolated compounds were elucidated using different spectroscopic techniques. A plausible biogenetic route of the new compounds was discussed. The anti-inflammatory activity of the isolated compounds was evaluated by superoxide anion generation and elastase release assays. Among the tested compounds, flexuvarol B and chrysin showed the most potent anti-inflammatory effect by inhibiting superoxide anion generation and elastase release from human neutrophils in response to fMLP with IC50 2.25–5.55 μM. Moreover, 5-hydroxy-6,7-dimethoxy-flavone showed selective inhibitory activity on superoxide anion generation (IC50 = 1.19 ± 0.34 μM).

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