Competitive α-glucosidase inhibitors, dihydrobenzoxanthones, from the barks of Artocarpus elasticus

Abstract

This study aimed to search the α-glucosidase inhibitors from the barks part of Artocarpus elasticus. The responsible compounds for α-glucosidase inhibition were found out as dihydrobenzoxanthones (1?4) and alkylated flavones (5?6). All compounds showed a significant enzyme inhibition toward α-glucosidase with IC50s of 7.6?25.4 μM. Dihydrobenzoxanthones (1?4) exhibited a competitive inhibition to α-glucosidase. This competitive behaviour was fully characterised by double reciprocal plots, Yang’s method, and time-dependent experiments. The compound 1 manifested as the competitive and reversible simple slow-binding, with kinetic parameters k3 = 0.0437 ?M?1min?1, k4 = 0.0166 min?1, and Kapp 1 = 0.3795 ?M. Alkylated flavones (5?6) were mixed type I (KI < KIS) inhibitors. The binding affinities (KSV) represented by all inhibitors were correlated to their concentrations and inhibitory potencies (IC50). Moreover, compounds 1 and 5 were identified as new ones named as artoindonesianin W and artoflavone B, respectively. Molecular modelling study proposed the putative binding conformation of competitive inhibitors (1?4) to α-glucosidase at the atomic level. ? 2019, ? 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.