Two new isoflavone compounds, Dalhancei A (1) and Dalhancei B (2), along with a known compound epicatechin (3) were isolated from 80% methanol extract of the barks of Dalbergia hancei Benth. The structures of compounds 1-3 were elucidated by comparison with the literature and physical data analysis, including optical rotation, MS, 1D and 2D NMR spectra. Compounds 1 and 2 showed weak inhibitory activity against tyrosinase at 16.22 mmol/L, with inhibition rates of 42.23 ± 0.18% and 45.68 ± 0.17%, respectively; compound 1 exhibited weak inhibitory activity against α-glucosidase with the inhibition rate of 43.72 ± 0.22% at 5.41 mmol/L, compounds 2 and 3 had better α-glucosidase inhibitory activity than compound 1 with IC50 values of 0.90 ± 0.18 and 0.41 ± 0.17 mmol/L, respectively.
Keywords: Dalbergia hancei Benth; isoflavone; structure; tyrosinase and α-glucosidase inhibiton.