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Three new isoprenylated chromones, named harriforatins A−C (1 − 3), along with 13 known compounds (4 − 16) were isolated from the stems of Harrisonia perforata. Their planar structures were elucidated by spectroscopic measurements. The experimental and calculated ECD curves were used to determine their absolute configurations. Most isolated compounds were evaluated for inflammation inhibition against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. Only compounds 5 and 6 showed inhibitory effects on NO production, with IC 50 values of 42.8 and 47.0 μM, respectively, that were stronger than that of the positive control, indomethacin (IC 50 = 68.6 μM). [Display omitted] • Three new isoprenylated chromones were isolated from Harrisonia perforata stems. • The structures with absolute configurations were established by extensive spectroscopic methods. • Two compounds showed a significant inhibitory effect on NO production. [ABSTRACT FROM AUTHOR]

The aims of this study are to investigate chemical compounds from Garcinia cowa Roxb. ex Choisy and evaluate their antidiabetic activities, including α-glucosidase inhibitory, α-amylase inhibitory, glycation, glucose consumption, and glucose uptake. The EtOAc extract of the twigs of Garcinia cowa Roxb. ex Choisy were separated and purified by chromatographic techniques to give eight compounds (1 – 8). Of these, a xanthone with 5,5,8a-trimethyloctahydro-2 H -1-benzopyran moiety, garciniacowone L (1), was isolated as a new compound, which was characterized by extensive spectroscopic data and high-resolution mass spectrometry. The known compounds were characterized by NMR spectroscopy techniques, and by comparisons of these data with those reported. All isolated compounds except β-mangostin (4) were evaluated for antidiabetic activities. Forbexanthone (8) exhibited good α-glucosidase inhibitory activity with an IC 50 value of 85.1 ± 0.3 µM. 1-Hydroxy-7-methoxyxanthone (7) inhibited the highest glycation activity with the IC 50 value of 170.3 ± 0.9 µM. From cell-based assays, mangostinone (3) showed glucose consumption and glucose uptake with the IC 50 value of 18.3 ± 0.5 µM and 2.9-fold, respectively. This study revealed that some xanthones isolated from Garcinia cowa Roxb. ex Choisy might be interesting for further evaluation as a new drug candidate for diabetes mellitus. [ABSTRACT FROM AUTHOR]