Antioxidant activity and inhibitory potential of Hibiscus rosa-sinensis flower extract against the key enzymes relevant for hyperglycemia: in-vitro and in-silico studies

Abstract

BACKGROUND: The alteration of endogenous antioxidants and generation of reactive oxygen species induce hyperglycemia which may lead to the emergence of chronic problems in diabetes. The key enzymes responsible for hyperglycemia are α-amylase and α-glucosidase. Owing to the various negative consequences caused by synthetic medicines, there is a requirement for natural antioxidants and inhibitors for α-amylase, and α-glucosidase enzymes to attenuate hyperglycemia. This article entails the antioxidant potential as well as the inhibitory potential of the Hibiscus rosa-sinensis flower extracts in contrast to the enzymes involved in regulating hyperglycemia.METHODS: Flower extracts were prepared using solvents with ascending polarity viz. hexane, chloroform, ethyl acetate, n-butanol, methanol, and distilled water by maceration. Antioxidant capacity was investigated using 2,2-diphenyl-1-picrylhydrazyl free radical activity, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid cation(s) scavenging assay, ferric ion reducing-antioxidant power assay, and total antioxidant capacity. The inhibitory efficacy against α-amylase and α-glucosidase enzyme were investigated by performing α-amylase, and α-glucosidase inhibitory assays. To validate the observed results in in-vitro assays, the existence of polyphenolic compounds in the most potent extract was detected using ultra-high-performance liquid chromatography (UHPLC). Furthermore, in-silico analysis of the detected polyphenols in the most potent extract was done to understand the binding energies and docking at different sites of α-glucosidase and α-amylase enzymes, and it was contrasted to standard (acarbose).RESULTS: The most significant amount of antioxidant activity was noticed in the ethyl acetate extract in all the assays. Moreover, the ethyl acetate extract had a stronger suppressant effect on α-glucosidase and α-ainilase enzymes than other extracts and it was more in the case of α-glucosidase (IC50 value 53.33 µg/mL) as compared to α-amylase (IC50 value 83.02 µg/mL) enzymes There was a finding that among the polyphenolic compounds detected from the ethyl acetate extract via UHPLC, in which the docking studies were carried out, caffeic acid showed maximum binding energy with the α-glucosidase enzyme while epicatechin showed maximum binding energy with the α-amylase enzyme.CONCLUSIONS: The whole study concluded that caffeic acid and epicatechin have shown good interactions with concerned enzymes, and hence might contribute to the inhibition of hyperglycemic conditions and other diabetic problems caused by oxidative stress.