Abstract

Polyphenolic compounds and metals in lyophilized mango peels were identified and antioxidant capacities of these extracts were evaluated using in vitro assays. The concentrations of calcium, potassium, sodium, phosphorus, copper, iron, magnesium, manganese, zinc, cadmium and nickel were 2177, 7149, 7.416, 542.6, 3.227, 12.78, 1270, 23.47, 3.833, 0.040 and 1.125, respectively. To obtain the phenolics, two extracts were obtained (Ext-5 and Ext-7) using 80% methanol and 80% acetone, at 25 and 37.5 °C with stirring for 30 and 60 min, respectively. The extracts were applied to solid-phase extraction (SPE) cartridges and analyzed by liquid chromatography (HPLC-diode array detector) to identify and quantify polyphenols. The DPPH and ABTS radicals scavenging capacity was evaluated in these extracts. Phenolic acids, flavonoids, and one xanthone were identified in both extracts, independently of the conditions used in the extraction process. Compounds identified include syringic and sinapic acids, as well as taxofolin, isoquercetin, and mangiferin. The results suggest that the extracts’ capacity to sequester DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2’-azino-bis(3- ethylbenzothiazoline-6-sulphonic acid)radicals was significant and may result from either the high concentrations of some of the identified polyphenols or synergy with polyphenols at lower concentrations.

Keywords: ABTS, Antioxidant capacity, antioxidants, DPPH, flavonoids, free radicals scavenging capacity, mango, metals, mango peel, phenolic acids, phenols.