Main Constituents and Antidiabetic Properties of Otholobium mexicanum.

Two phenols, bakuchiol (1) and 3-hydroxybakuchiol (2), and two isoflavone glycosides, daidzin (3) and genistin (4) were isolated from Otholobium mexicanum J. W. Grimes (Fabaceae). Moreover, the ability of the raw extract and isolated metabolites to inhibit the enzymes α-amylase and α-glucosidase was evaluated in vitro. In the α-amylase assay, the methanolic extract exhibited a moderate inhibitory activity with an IC₅₀ of 470 μg/mL, while inhibition percentages of bakuchiol (1), 3-hydroxybakuchiol (2), and daidzin (3) were less than 25% at the maximum dose tested (1 μM). Genistin (4) exhibited a poor activity with an IC₅₀ of 805 μM. In the α-glucosidase assay, the methanolic extract exhibited a strong inhibitory activity with an IC₅₀ value of 32 μg/mL, while 3-hydroxybakuchiol (2) exhibited a moderate inhibitory activity with an IC₅₀ of 345 μM. Daidzin (3) and genistin (4) exhibited lower inhibitory activity with IC₅₀ values of 564 μM and 913 μM, respectively. Bakuchiol (1) exhibited a poor inhibitory activity with an inhibition percentage less than 10% at the maximum dose tested (1 mM).