Discovery, biological evaluation and docking studies of novel N-acyl-2-aminothiazoles fused (+)-nootkatone from Citrus paradisi Macf. as potential α-glucosidase inhibitors.

Nowadays, the discovery and development of α-glucosidase inhibitors from natural products or their derivatives represents an attractive approach. Here we reported studies on a series of novel N-acyl-2-aminothiazoles fused (+)-nootkatone and evaluation for their α-glucosidase inhibitory activities. Most of (+)-nootkatone derivatives exhibited more potent α-glucosidase inhibitory ability than the positive drug acarbose. In particular, compounds II7 and II14 showed the most promising α-glucosidase inhibitory ability with IC values of 13.2 and 13.8 µM. II7 and II14 also exhibited relatively low cytotoxicities towards normal LO2 cells. Kinetic study indicated that compounds II7 and II14 inhibited the α-glucosidase in a noncompetitive manner, and molecular docking results were in line with the noncompetitive characteristics that II7 and II14 did not bind to the known active sites (Asp214, Glu276 and Asp349). Based on our findings, these (+)-nootkatone derivatives could be used as antidiabetic candidates.