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The first phytochemical investigation of the twig extract of Uvaria leptopodaresulted in the isolation and identification of three new tetrahydroxanthene-1,3(2H)-diones, uvarialeptones A–C, two new oxidized hexadiene derivatives, uvarialeptols A and B, together with ten known compounds. Their structures were elucidated by spectroscopic techniques and mass spectrometry. Uvarialeptones A and B were unprecedented tetrahydroxanthene-1,3(2H)-dione dimers which exhibited a cyclobutane ring via [2 + 2] cycloaddition from uvarialeptone C and 9a-O-methyloxymitrone, respectively. The structure of uvarialeptone A was confirmed by X-ray diffraction analysis using Mo Kα radiation. Compound 3inhibited NO production at an IC50value of 6.7 ± 0.1 μM.

Five new compounds—two phloroglucinol benzophenones, garciniacowones F (1) and G (2), and three xanthones, garciniacowones H (3), I (4), and J (5)—together with seven known xanthones (6–12) were isolated from the fresh leaves of Garcinia cowa. Their structures were elucidated by detailed analysis of NMR and MS data. Compounds 1and 2are phloroglucinol benzophenones containing a polyprenylated bicyclo[3.3.1]nonane ring system, while compounds 3–5are rare xanthones having farnesyl (3and 5) and geranylgeranyl (5) units at C-8. Compounds 1, 3, 4, 7, 8, and 10exhibited inhibitory effects on NO production in LPS-induced RAW264.7 macrophage cells with IC50values ranging from 5.4 to 18.6 μM. Compounds 4and 8had α-glucosidase inhibitory activities with IC50values of 15.4 and 11.4 μM, respectively, which were more potent than that of the acarbose control.