Anti-inflammatory and α-glucosidase inhibitory constituents from Dendrobium nobile Lindl

Abstract

Four new compounds ((±)-1–3), including one pair of enantiomers ((±)-1), along with 11 known bibenzyls (4–14) were isolated from Dendrobium nobile. The structures of the new compounds were elucidated by spectroscopic methods including 1D and 2D NMR as well as HRESIMS. The configurations of (±)-1 were established via the electronic circular dichroism (ECD) calculations. Compounds (+)-1 and 13 displayed pronounced α-glucosidase inhibitory activities with IC50 values of 16.7 ± 2.3 and 13.4 ± 0.2 μM, respectively, which were comparable to that of genistein (IC50, 8.54 ± 0.69 μM). Kinetic studies revealed that (+)-1 and 13 were non-competitive inhibitors against α-glucosidase and molecular docking simulations illuminated their interactions with α-glucosidase. All the isolates were also evaluated for their anti-inflammatory activities. Compounds 4, 5, and 11 exhibited superior inhibition activity with IC50 values ranging from 9.2 to 13.8 μM to that of quercetin (IC50, 16.3 ± 1.1 μM).