Antibacterial, antifungal and antioxidant activity of total polyphenols of Withania frutescens.L

Abstract

Our objective in this work is evaluated the antibacterial, antifungal and antioxidant activity of the phytochymic compounds of the roots and leaves of a species Withania frutescens. In the first part, the phenolic compound is determinate by the Folin-Ciocalteau reaction, the richness of the roots in polyphenols (53.33 ± 1.20 mg EGA/g Extract) is six times higher than that of the leaves. The antioxidant test is evaluated by four methods: DPPH test, reducing power test (FRAP), total antioxidant capacity (CAT) and the ß-carotene discoloration test. The IC-50 values of the DPPH test of the studied parts are of the order of 0.36 µg/ml and 6.63 µg/ml, which showed a lower anti-free radical activity than that of BHT (0.12 µg/ml). The results obtained by the FRAP method revealed a low reducing power of iron for two extracts (EC-50 of 0.45%) compared to Quercetine (EC-50 of 0.03%). The compounds of root and leaf extracts have a significant total antioxidant capacity, respectively 477.65 ± 37.60 and 317.03 ± 46.64 mg EAA/g Extract. In the β-carotene discoloration test, extracts from the aerial and underground parts showed antioxidant activity of 57% followed by (36%), respectively. The evaluation of the antibacterial activity of in vitro extracts against microorganisms is carried out by two methods: disc diffusion and microdilution. The results show that the extracts exert an intermediate inhibitory effect (inhibition diameter between 8 and 15 mm, the smallest MIC obtained is 2.80 mg/ml) on all strains tested. The antifungal activity was estimated by determining the growth inhibition rate of the fungus tested. Indeed, the compounds studied exhibit a good antifungal effect since the minimum inhibitory concentration (MIC) of 4.5 mg/ml for root extract and 9 mg/ml for leaf extract.