Antidiabetic and antimicrobial flavonoids from the twigs and roots of Erythrina subumbrans (Hassk.) Merr

The phytochemical investigation of the twig and root extracts of Erythrina subumbrans (Hassk.) Merr. (Fabaceae) resulted in the isolation and identification of a new pterocarpan, erythrinocarpan (1), along with 27 known compounds (2-28). All isolated compounds were evaluated for their antidiabetic, anti-microbial, and anti-inflammatory properties. Compounds 3, 8, 9, and 22 had alpha-glucosidase inhibitory activity with IC50 values of 13.4 +/- 0.05, 24.5 +/- 0.13, 29.0 +/- 0.05, and 12.8 +/- 0.14 mu M, respectively, while compound 2 inhibited alpha-amylase activity with an IC50 value of 67.6 +/- 1.12 mu M. Compounds 22 and 24 inhibited glycation activity with the IC50 values of 36.9 +/- 0.62 and 40.5 +/- 0.37 mu M, respectively. From cell-based assays, compound 27 showed the highest ability to induce glucose consumption (IC50 29.1 +/- 0.86 mu M) and glucose uptake (2.8-fold), and to inhibit nitric oxide (NO) production (IC50 52.5 +/- 0.56 mu M) without cell toxicity. Furthermore, compound 9 showed antimicrobial activities against Gram-positive bacteria and fungi with MIC values ranging from 2-4 mu g/mL.