Free radical scavenging activity, phenolic contents and phytochemical evaluation of different extracts of stem bark of Butea monosperma (Lam.) Kuntze

The antioxidant activity, phenolic contents and phytochemical profile of acetone, methanol, water and ethyl acetate extracts of the stem bark of B. monosperma were investigated. Extracts showed highest antioxidant activity at 100gml(1) with application of different assays: 2-2 diphenyl2 picrylhydrazyl (DPPH) scavenging (83.5% and 78.1%), reducing power (1.85 and 1.78), deoxyribose degradation site-specific (65.5% and 61.5%) and non-site-specific (67.1% and 66.5%) and chelating power (63.4% and 58.9%) in decreasing and increasing polarity of acetone extracts, respectively. However, nitroblue tetrazolium (NBT) showed scavenging of O-2 center dot radicals by 56.4% and 53.1% in decreasing and increasing polarity methanol extracts, respectively. Similarly, electron paramagnetic resonance (EPR)/spin-trapping exhibited highest radical scavenging activity with acetone extracts (12.6mgg(1) Trolox). The results pointed to the significant antioxidant activities in acetone and methanol extracts. In most cases, the extracts obtained through decreasing polarity showed higher antioxidant activity. The phenolic content exhibited a strong association (r(2)>0.9) with antioxidant activity. These results suggest that bark of B. monosperma can be a potential source of natural antioxidants.