Metabolomics and chemometrics-driven valorisation of mango leaves: Unveiling putative α-amylase and α-glycosidase inhibitory metabolites

Abstract

This study presents a comprehensive investigation into the metabolite composition of various mango leaf samples using Ultra Performance Liquid Chromatography-High Resolution Mass Spectrometry (UPLC-HRMS). A total of 103 chromatographic peaks representing diverse metabolite groups were annotated, revealing significant variations in chemical composition among different mango varieties. Polyphenols emerged as the most abundant class, with mangiferin being the major polyphenol detected in most varieties, including Awis, Sukari, Sinara, Sedika, and Alfonse. Trihydroxybenzoyl mangiferin was predominant in Sedika and Alfonse varieties. Flavonoids, such as flavanone glycosides and flavone glycosides, were also prominent. O-methylnaringenin pentoside was the major flavanone glycoside detected in Awis, Sukari, and Sinara varieties, while naringenin-O-hexoside was predominant in Alfonse. Phenolic acids were detected across all varieties, with protocatechuic acid and gallic acid being major components. Protocatechuic acid was identified in all varieties except Sedika and Naomi, where gallic acid dominated. Kaempferol and di-O-methylquercetin were exclusively detected in the Naomi variety. In-vitro enzyme inhibition assays against α-amylase and α-glycosidase enzymes revealed dose-dependent inhibitory effects of mango leaf extracts, with variations in potency among varieties. The most potent inhibitors of α-amylase activity were found in extracts from Sukari and Alfonse leaves, while those from Sukari and Sedika leaves showed the strongest inhibition of α-glycosidase activity. Interestingly, the extracts that exerted the highest inhibition of α-amylase activity did not necessarily inhibit α-glycosidase activity significantly. Additionally, glucose uptake promotion assays identified Awis and Sedika leaves as the most potent promoters of glucose uptake.