Phytochemical compounds of Guibourtia ehie and their antioxidant, urease and α-glucosidase inhibitory activities

Thirteen compounds (1‒13) were isolated and identified during phytochemical analysis of the leaves and stem bark of Guibourtia ehie (A. Chev) J. Leonard. Spectroscopic and spectrometric methods and the comparison of their results with those given in the literature were used to ascertain their structures. Furthermore, the acetylation of 3,3′-di-O-methylellagic acid 4′-O-β-D-xylopyranoside (2) afforded a new derivative 3,3′-di-O-methylellagic acid 4′-O-β-D-(4,2′′,4′′-triacetyl)-xylopyranoside (2a). Extracts, fractions, and isolated compounds were assessed for their antioxidant, urease, and α-glucosidase inhibitory activities. Compound 1 demonstrated potent antioxidant activity in the DPPH with an IC50 value of 36.4 ± 0.2 µM, while rhaponticin (3), 2,6-dimethoxybenzoquinone (4), and taraxerol (6) exhibited a strong α-glucosidase inhibitory activity with the IC50 values of 35.5 ± 0.1, 25.5 ± 0.2 and 43.4 ± 0.3 µM, respectively. The present study enriches the chemistry of Guiboutia ehie and provides further evidence on its bioactive constituents, which might help in the development of hypoglycaemic drugs.