Flavonoids and oxepinones from the leaves and twigs of Desmos cochinchinensis and their α-glucosidase inhibitory activities

Desmos cochinchinensis, belonging to the Annonaceae family, is a shrub widely distributed in Asia. Several secondary metabolites including, terpenoids, alkaloids, chalcones, and flavonoids have been isolated from this plant. Some of these compounds showed useful biological properties including antitumor, anti-inflammatory, antiviral and anti-HIV activities. Herein, twenty-four compounds comprising four new flavonoids (1–4), a new benzyl benzoate derivative (5), five new oxepinones (6–10), and fourteen known compounds were isolated and purified from the twigs and leaves of D. cochinchinensis by various column chromatographic techniques. Their structures were established by spectroscopic methods. The structure of compound 1 was confirmed from X-ray diffraction data with Mo Kα radiation. The absolute configurations of 3, 4, and 6–10 were identified from comparisons of their ECD spectra with those reported compounds. Compounds 1, 2, 6, 8, and 10 showed α-glucosidase inhibitory activities with IC₅₀ values of 0.2, 0.2, 3.6, 4.9, and 3.1 µM, respectively, which were better than the positive control, acarbose, (IC₅₀ 170.7 µM).

Fig. 1

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