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The first phytochemical investigation of the twig extract of Uvaria leptopoda resulted in the isolation and identification of three new tetrahydroxanthene-1,3(2 H )-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(2 H )-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 3 inhibited NO production at an IC 50 value 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 1 and 2 are phloroglucinol benzophenones containing a polyprenylated bicyclo[3.3.1]nonane ring system, while compounds 3 - 5 are rare xanthones having farnesyl ( 3 and 5 ) and geranylgeranyl ( 5 ) units at C-8. Compounds 1 , 3 , 4 , 7 , 8 , and 10 exhibited inhibitory effects on NO production in LPS-induced RAW264.7 macrophage cells with IC 50 values ranging from 5.4 to 18.6 μM. Compounds 4 and 8 had α-glucosidase inhibitory activities with IC 50 values of 15.4 and 11.4 μM, respectively, which were more potent than that of the acarbose control.