Enzymatic synthesis, structural analysis, and evaluation of antibacterial activity and α‐glucosidase inhibition of hesperidin glycosides

Abstract

This study was designed to investigate the structure of synthesized hesperidin glycosides (HGs) and evaluate their antibacterial and α‐glucosidase inhibitory activities. The preliminary structure of HGs was confirmed by glucoamylase treatment and analyzed on thin layer chromatography (TLC). The LC‐MS/MS profiles of HGs showed the important fragments at m/z ratios of 345.21 (added glucose to glucose of rutinose in HG1) and 687.28 (added maltose to glucose of rutinose in HG2), confirming that the structures of HG1 and HG2 were α‐glucosyl hesperidin and α‐maltosyl hesperidin, respectively. In addition,1H and13C‐NMR of hesperidin derivatives were performed to identify their α‐1,4‐glycosidic bonds. The MIC and MBC studies showed that transglycosylated HG1 and HG2 had better antibacterial and bactericidal activities than hesperidin and diosmin, and were more active against Staphylococcus aureus than Escherichia coli. Hesperidin, HG1, HG2, and diosmin inhibited α‐glucosidase with IC50 values of 2.75 ± 1.57, 2.48 ± 1.61, 2.36 ± 1.48, and 2.99 ± 1.23 mg/mL, respectively. The inhibition kinetics of HG2 shown by a Lineweaver–Burk plot confirmed HG2 was an α‐glucosidase competitive inhibitor with an inhibitor constant, Ki, of 2.20 ± 0.10 mM. Thus, HGs have the potential to be developed into antibacterial drugs and treatments for treating α‐gluco-sidase‐associated type 2 diabetes.