Study on the stability of four flavonoid glycoside components in Myrica Rubra pomace and their mechanism of in vitro hypoglycaemic activity

In order to investigate the hypoglycaemic mechanism and potential applications of four hypoglycaemic flavonoid glycosides, namely myricitrin, Cyanidin-3-O-glucoside (C3G), hyperoside and quercitrin in Myrica rubra pomace, the stability of these four flavonoid glycosides and their binding mechanisms were studied using molecular docking. The results demonstrated that pH value affects on the stability of these four components in M. rubra pomace. C3G exhibited the most significant inhibitory effect on α-glucosidase at pH 5, with myricitrin, hyperoside and quercitrin showing the highest inhibitory effect at pH 7. Moreover, an increase in temperature and storage time reduced the inhibitory effect of these four glycosidic components on α-glucosidase. Molecular docking analysis revealed that myricitrin formed hydrogen bonds with the active site residues of α-glucosidase, namely Phe550, Ile552, Asp555, Ser574 and Arg576, and also engaged in hydrophobic interactions with Lys551. Hyperoside formed hydrogen bonds with α-glucosidase, formed hydrophobic interactions with Lys50 and exhibited π-cation interaction with Lys53. Quercitrin formed hydrogen bonds with α-glucosidase, formed hydrophobic interactions with Lys500 and established salt bridges with Lys50. C3G formed hydrogen bonds and hydrophobic interactions with α-glucosidase and showed π-π interactions with Phe301. These findings will provide valuable insights for the application of these four chemicals.