Phytochemical Screening, Total Phenolic and Antioxidant Activity of Numerous Extracts from Leaves and Bark of <i>Bauhinia rufescens</i>Lam

Researches for natural antioxidants that play an important role in the prevention of diseases linked to free radicals have increased in recent years. In this study, antioxidant activity of Bauhinia rufescens Lam which is a medicinal plant was investigated. The methanol extract, acetone extract and water extract of leaf and trunk bark had antioxidant activity. Three methods were used: 2,2-diphenyl-1picryl-hydrazyl (DPPH), 2,2’-Azino-bis-(3-ethylbenzoth iazoline-6-sulfonic acid) (ABTS) and ferric ion reducing power (FRAP) by spectrophotometry. Phytochemical screening was carried out followed by the quantification of the total phenolic by the Folin-Ciocalteu method. The analysis of variance (ANOVA) with the STATISTICA 7.1 software revealed significant differences (p < 0.05). Percentage inhibition (PI) and IC50 of the extracts were obtained using the OriginPro 8.5 software. These tests show that the bark is as rich in total phenolic as the leaves. The DPPH test shows that at 2.5 mg/ml, the bark and the leave have similar activity. Bark has a percentage inhibition (PI) of 86.55% ± 0.026% compared to the leave which PI is 85.63% ± 0.02%. As for the ABTS test, the bark extract reached its maximum activity at 2.5 mg/ml with a PI of 99.81% ± 0.012% compared to the leaf extract which has a PI of 99.61% ± 0.025%. The best IC50 of the extracts obtained with the DPPH radical is 0.139 ± 0.001 mg/ml (hydro-acetonic), 0.354 ± 0.001 mg/ml (hydromethanolic) and 0.840 ± 0.001 mg/ml (aqueous) on the bark. With ABTS test, it was obtained 0.351 ± 0.001 mg/ml (hydro-acetone;bark), 0.403 ± 0.001 mg/ml (hydro-acetone;leaves) and 0.474 ± 0.001 mg/ml (aqueous;bark). The reducing power of the leaves is slightly higher than that of the bark. Standard of ascorbic acid, has a PI of 94.86 ± 0.008% with an IC50 of 0.213 ± 0.001 mg/ml. Thus, it is easy to conclude that the bark of Bauhinia rufescens has a better activity than the leaves and the alcoholic extracts have given better results than the aqueous extract.