α-Glucosidase inhibitory and nitric oxide production inhibitory activities of alkaloids isolated from a twig extract of Polyalthia cinnamomea.

•Thirteen compounds were isolated and identified from Polyathia cinnamomea twigs.•Oxoprotoberberine alkaloids are the major compounds of P. cinnamomea species.•Two compounds were confirmed absolute configuration by X-ray diffraction data.•Six compounds exhibited α-glucosidase inhibitory activity better than acarbose.•(−)-(13aS)-consanguine B exhibited NO inhibitory activity better than indomethacin.