Evaluation of the Antioxidant and Anti-diabetic Bioactivities of Natural Phenolics from Mango (Mangifera indica Linn) Branches

Abstract

Different parts of the mango (Mangifera indica Linn) tree are known to contain phenolic compounds that exhibit health-promoting bioactivities. Branches that were cut off during pruning having no significant economic value were utilized as a source for phenolic compounds in this study. Antioxidant and anti-diabetic activities of the extracted phenolics from branches of five mango varieties (“apple mango,” “carabao,” “pico,” “sinaging,” and “sipsipin”) were evaluated. The bioactivities of the phenolic extracts from mature and young branches of carabao and pico varieties were also compared. Three different methods were used to quantify the antioxidant capacity of the phenolic compounds – namely, the DPPH (2,2-diphenyl-1- picrylhydrazyl) radical scavenging activity assay, ABTS [2,2’-azino-bis (3-ethyl-benzothiazoline6-sulfonic acid) diammonium salt] cation radical scavenging assay, and CUPRAC (cupric ion reduction antioxidant capacity) test. Anti-diabetic effects were evaluated by quantifying the α-amylase and α-glucosidase inhibitory activities of the phenolic extracts. Findings showed that the bioactivities were variable with respect to the varieties and maturity of the mango branches. The varieties apple mango, pico, and sinaging exhibited the highest antioxidant activity based on their EC50 values interpolated from the DPPH scavenging, ABTS scavenging, and CUPRAC assays, respectively. The anti-diabetic properties of the phenolics extracted from mango branches showed better bioactivity than the known anti-diabetic drugs, acarbose, and metformin. The findings of this present study offer a potentially huge economic impact to mango farmers as the extraction of phenolics from mango branches for medical supplement use can be a viable alternative and/or supplementary income source.