Determination of Antioxidant Activity and Phytoconstituent Screening of Euphorbia heterophylla Linn

Aim: To carry out qualitative determination of phytochemicals and evaluate antioxidant potential of Euphorbia heterophylla Linn.
Place and Duration of Study: Department of Chemistry, Government College University Lahore, Pakistan, between October, 2011 and February, 2012.
Material and Method: The methanolic extract of the plant was dissolved in distilled water and partitioned with n-hexane, chloroform, ethyl acetate and n-butanol sequentially. The antioxidant potential of all these fractions and remaining aqueous fraction was analyzed by these methods: 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging activity, total antioxidant activity, Ferric Reducing Antioxidant Power (FRAP) assay, Ferric Thiocyanate (FTC) assay while Folin-Ciocalteu colorimetric method was used to analyse total phenolic content. Phytochemical analysis were performed on the plant extracts to detect the presence of secondary metabolites.
Results: Phytochemical screening revealed phenolics and flavonoids in abundance in chloroform soluble fraction, ethyl acetate soluble fraction and n-butanol soluble fraction. Also the ethyl acetate soluble fraction, n-butanol soluble fraction and remaining aqueous fraction contained saponins and sugars. Terpenoids were detected in all other fractions except the aqueous fraction. Alkaloids were determined in ethyl acetate and n-butanol soluble fraction only while tannins and cardiac glycosides were present in n-butanol soluble fraction and ethyl acetate soluble fraction respectively. Antioxidant assays revealed that Ethyl acetate soluble fraction exhibited highest percent inhibition of DPPH radical i.e. 80.09±0.87% at a concentration of 120 μg/ml as compared to other fractions. IC50 value of ethyl acetate fraction was found to be 36.85±1.8 μg/ml relative to ascorbic acid having IC50 value 58.8±0.89 μg/ml. It also showed the highest value of total antioxidant activity i.e. 0.918±0.08 as well as highest FRAP value 200.05±0.4 TE μM/ml, highest amount of total phenolic compounds (190.1±1.21 GAE mg/g) and highest percentage of inhibition of lipid peroxidation (54.23±0.57%). Chloroform soluble fraction showed IC50 value of 149.84±1.02, total antioxidant activity 0.739±0.06; FRAP value115.15±0.2 μM/ml, total phenolic content 137.1±1.4 GAE mg/g and 41.31±0.53% percent inhibition of lipid peroxidation. n-Butanol soluble fraction showed IC50 value of 117.67±0.7, total antioxidant activity 0.532±0.03, FRAP value127.5±0.9 μM/ml, total phenolic content 93.5±0.3 GAE mg/g and 32.15±0.9% percent inhibition of lipid peroxidation. n-Hexane soluble fraction showed IC50 value of 769.7±1.5, antioxidant activity 0.174±0.07, FRAP value 98.26±0.8 μM/ml, total phenolic content 19.5±1.23 GAE mg/g and 12.09±0.8% percent inhibition of lipid peroxidation. Aqueous fraction showed IC50 value of 669.3±1.04, antioxidant activity 0.152±0.041; FRAP value 68.7±0.3 μM/ml, total phenolic content 36.3±0.9 GAE mg/g and 25.01±0.96% percent inhibition of lipid peroxidation.
Conclusion: Ethyl acetate soluble fraction was found to be rich in natural antioxidants and a good source of phytochemicals.