Antioxidant Activity of Hydro-Acetonic, Hydro-Methanolic and Aqueous Leaf and Bark Extracts of <i>Sclerocaria birrea</i> (A. Rich.) Hochst

Abstract

Bioactive compounds in plants are associated with the reduction of chronic diseases. The free radical scavenging activity of different extracts of a medicinal plant, Sclerocarya birrea, has been investigated using the DPPH test, ABTS test and FRAP. Three extracts were prepared from the leaves and bark: hydro-methanolic, hydro-acetonic and aqueous. Phytochemical screening was carried out the standard methods followed by the determination of the polyphenol by Folin-Ciocalteu method. The analysis of variance (ANOVA) with the STATISTICA 7.1 and statistical significance was set at p 0.05. Evolution of percent inhibition (PI) as well as the IC50 of the extracts was obtained using the Origin Pro 8.5 software and Microsoft Excel. The results show that the bark extracts are about twice as rich in polyphenols as the leaves. With DPPH at 1.25 mg/mL, the bark has a PI of 91.04% ± 0.001% while leaves, reach 99.80% ± 0.021%. As for the ABTS test, the bark extract reached its maximum activity at 1.25 mg/mL with a PI of 99.80% ± 0.003% while leaves extract greater value of PI is 99.75 ± 0.003 at 2.5 mg/mL. With FRAP test at 1.25 mg/mL, the bark has a PI of 79.29% ± 0.005% while leaves, reach 80.33% ± 0.001%. The IC50 of the bark and leaf extracts on the smallest DPPH are 0.156 ± 0.001 mg/mL in hydro-methanol, 0.301 ± 0.00 mg/mL in hydro-acetone and 0.407 ± 0.00 mg/mL in aqueous extract. With ABTS test, the best IC50 are obtained with hydro-acetone extracts with value of 0.247 ± 0.001 mg/mL for bark and 0.248 ± 0.0005 mg/mL for leaves while in hydro-methanolic and aqueous extracts the best IC50 are respectively 0.255 ± 0.00 mg/mL and 0.463 ± 0.00 mg/mL. Using ascorbic acid as our standard, the PI was 94.86% ± 0.008% with an IC50 of 0.213 ± 0.00 mg/mL. According to these results, the reducing power of the bark is slightly higher than that of the leaves. We can say that the bark has better activity than the leaves and the alcoholic extracts have given better results than the aqueous extract.