A Study on the Antioxidant and Antimicrobial Activities of Seed and Leaf Extracts of Glycine max (L) Merr.

Abstract

The present study was carried out to evaluate the antioxidant and antimicrobial activities of ethanolic leaf and seed extracts of Soybean (Glycine max (L) Merr.). Antioxidant activity of the leaf and seed extracts was determined by reducing power capacity of flavonoid, phenol, lycopene, β-carotene and ascorbic acid using standard laboratory method. The antimicrobial assay of the leaf and seed extracts was carried out at different concentrations against some selected clinical pathogens (bacterial strains: Staphylococcus aureus, Escherichia coli; fungi strain: Candida albicans, Aspergillus niger) using agar diffusion method. Analysis of variance was employed in data analysis. Antioxidant phytochemical composition of the leaf and seed extracts of Glycine max revealed that all the phytochemicals assayed were present but in various amounts except ascorbic acid that was absent in the leaf. The quantities of the phytochemicals were higher in the leaf than in the seed except for lycopene that was higher in the seed and ascorbic acid that was present only in the seed. The Reducing Power Capacity of the ethanol extract of the leaf and seed of the Glycine max indicated that Glycine max extracts though had a reducing power capacity but is very low in comparison with the standard used. The effectiveness of the extracts increases slightly as the concentration increases. Antimicrobial studies indicated that the ethanolic leaf and seed extracts of Glycine max inhibited the growth of the investigated microbes and the inhibition was concentration dependent. The leaf extract showed higher inhibition than the seed. However, the ethanolic leaf and seed extracts showed no inhibition against bacterial strains at 50 mg/ml. Data obtained from the studies showed that the plant possessed antioxidant and antimicrobial properties and could be used in the treatment of microbial infections especially fungi infections and also to protect cells against free radical and excessive light damages. However, the leaf extract showed better inhibition than the seed extract indicating that it is a better antimicrobial agent than the seed.