Chemical constituents from the seeds of Cassia obtusefolia and their in vitro α-glucosidase inhibitory and antioxidant activities.

ABSTRACT

Basing on chromatographic separation techniques, fifteen aglycones (1-15), including two new anthraquinone aglycones (1, 2) and thirteen known compounds (3-15), were isolated from the small polar fraction of Cassia obtusefolia (petroleum ether extract). Structural elucidations were performed by 1D/2D NMR spectroscopy and mass spectrometry. The in vitro antioxidant and α-glucosidase inhibitory activities of these fifteen compounds were determined. Except compounds 12 (IC50 3.03 ±â€¯0.31 µg/mL, stronger than ascorbic acid, which IC50 was 6.48 ±â€¯2.30 µg/mL) and 13 (IC50 78.40 ±â€¯2.39 µg/mL), the free radical scavenging capacities of other compounds were weak. Compounds 4, 5, 6 and 13 exhibited inhibitory activities on α-glucosidase with IC50 values of 50.60 ±â€¯1.10, 22.57 ±â€¯0.07, 60.09 ±â€¯1.40, and 80.01 ±â€¯2.66 µg/mL separately, however, all the α-glucosidase inhibitory activities were weaker than positive control (acarbose).