Concise synthesis and antidiabetic activity of natural flavonoid glycosides, oroxins C and D, isolated from the seeds of Oroxylum indium

The first concise synthesis of natural flavonoid glycosides, oroxins C (1) and D (2), which were isolated from the seeds of Oroxylum indicum, was efficiently achieved by a convergent strategy. The synthesized natural products 1 and 2 were evaluated for their inhibitory activities against α-glucosidase, α-amylase, and lipase. Compound 1 showed strong α-amylase and lipase inhibition, with IC50 values of 210 and 190 μM, respectively, but exhibited no inhibitory activity against α-glucosidase. Compound 2 showed strong inhibition against α-glucosidase and lipase, with the respective IC50 values of 180 and 80 μM.