DETERMINATION OF POLYPHENOLS CONTENT, ANTIOXIDANT AND ANTIBACTERIAL ACTIVITY OF NIGELLA SATIVA L. SEED PHENOLIC EXTRACTS

Abstract

In this work, we studied the phenolic extracts of the seeds of Nigella sativa L., from the point of view of the chemical composition and the antioxidant activity. The extraction of polyphenols was carried out using two different solvent systems, namely methanol: water 7: 3 (v / v) and acetone: water 7: 3 (v / v). The qualitative and quantitative analysis of methanolic and acetonic extracts by HPLC (High Performance Liquid Chromatography) revealed the presence of gallic acid, apigenin, naringenin, rutin, quercetin and kaempferol. The quantification of total phenols by Folin-Ciocalteu colorimetric method and flavonoids by the AlCl3 method gave higher values with the methanolic extracts compared to the acetonic extract. The total polyphenol content of the methanolic extract 1.3714 ± 0.0315 mg/g (mg GAE / g dw) is more elucidated than the content in acetone extract 0.5962 ± 0.0046 mg/g (mg GAE/g dw). The evaluation of the antioxidant power of the phenolic extracts was made by two chemical tests namely the DPPH test and the β-carotene bleaching test and we finished this work by studying the antibacterial and antifungal activity of these phenolic extracts.

Keywords

• antibacterial activity
• antifungal activity
• antioxidant activity
• flavonoids
• HPLC
• polyphenol