SYNTHESIS OF FUROFURAN LIGNANS FROM SAMIN THROUGH CARBON–CARBON BOND FORMATION WITH PHENOLICS

Abstract

Furofuran lignans contaning 2,6-diaryl-3,7-bicyclo [3.3.0] octane skeleton were synthesized by two-step sequential process. The synthesis was first performed by converting sesamolin, obtained from saponification of sesame oil, to the more reactive compound named samin, under acid-catalyzed condition. Subsequently, a series of furofuran lignans were synthesized through Friedel-Crafts type between samin and various phenolics (namely a-k). The reaction produced desired products (3a-3k) along with their epimers (epi-3a-epi-3k) with good yields. The synthesized furofuran lignans were further evaluated for antioxidant and α-glucosidase inhibitory activity. Of synthesized compounds, the products having free hydroxyl group on phenolic ring (3a, 3e, 3g, 3i, 3k, 1-3, 1-22 and their epimers) showed remarkable both antioxidant (SC50 0.22-1.45 mM and 0.15-0.41 mM toward DPPH and ABTS, respectively) and α-glucosidase inhibitory activity (IC50 1.14-8.23 mM against maltase). An enzyme kinetic study represented by 1-22 revealed that mode of inhibition was mixed-competitive against maltase with Ki and Ki´ value of 0.29 and 0.48 mM, respectively. These revealed that the free hydroxyl group on phenolic ring played an important role in enhancing antioxidant activity and enzyme inhibitory potency.