PHYTOCHEMICAL PROPERTIES AND IN VITRO ANTIOXIDANT ACTIVITY OF ACACIA NILOTICA (L.) WILLD.EX DEL. EXTRACTS

The aim of this research was to investigate the phytochemical composition and the antioxidant activity of the Acacia nilotica extracts. The samples (fruits and trunk bark of Acacia nilotica L.) were collected in Kayes (Mali). The phenolic compounds of the different plant extracts were assayed by spectrophotometry and identified by HPLC. The antioxidant efficacy of the extracts was evaluated by using 2, 2-azinobis-3-ethylbenzothiaz oline-6-sulfonic acid (ABTS) and 2, 2-Diphenyl-1-Picrylhydrazyl (DPPH)radicals scavenging capacities. The obtained results revealed that all the extracts are rich on polyphenols, flavonoids, tannins and anthocyanins. The contents of total polyphenols varied from 147 to 215 mg EAG/100 g, of total flavonoids from 1123 to 3037 mg EC /100 g, of total tannins from 67 to 289 mg EC/100 g and of total anthocyanins from 57 to 144 mg ECG / 100g of dry matter (DM). The highest values of those compounds ​​were recorded in fruit extracts with respectively 215 mg EGA, 3037 mg EC, 289 mg EC and 144 mg ECG/100g (MD).HPLC analysis of fruit extracts revealed the presence of a flavonoid, named rutin, and four phenolic compounds, gallic, protocatechuic, chlorogenic and caffeic acids, which are recognized as bioactive compounds. All of our studied extracts displayed highest ABTS and DPPH radical scavenging capacities. The values ​​varied from 72 to 350 mg EVC/100g (DM). The antioxidant activities of extracts were significantly correlated to their high contents of total phenolic and total flavonoids compounds. These justify the medicinal properties of the plant.