Total phenolic contents and determination of Antioxidant activity by DPPH, FRAP, and cyclic voltammetry of the fruit of Solanum nigrum (Black nightshade) growing in the south of Algeria

In the present research, we studied the quantification of the total phenolics, total flavonoids, total flavonols, and the evaluation of the antioxidant activity of the fruits of Solanum nigrum L. by chemical and electrochemical methods. The chloroform, ethyl acetate, and n-butanol crude extracts are prepared from the hydroethanolic extract of the fruits were tested. The results showed that ethyl acetate extract showed the highest phenolic content (87.68mg GAE/g), chloroform extract showed the highest flavonoid content (24.23mg QE/g) and highest flavonol content (71.60mg RE/g). The evaluation of antioxidant activity by chemical methods revealed that the highest DPPH radical scavenging activity was shown by ethyl acetate extract (0.123mg/mL) while the highest ferric reducing capacity was shown by butanol extract (610.46±0.0015mg FeSO4/g). The electrochemical study of the three extracts by cyclic voltammetry method indicates that the highest antioxidant activity was shown by ethyl acetate extract (17.75±0.238mg/g) equivalent ascorbic acid. The superoxide scavenging assay of chloroform extract showed the highest value (0.8 mg/mL).