Antioxidant capacity of crude water and ethyl acetate extracts of some Indian spices and their antimicrobial activity against Vibrio vulnificus and Micrococcus luteus

Abstract

The water and ethyl acetate extracts of six Indian spices were screened to identify their antioxidant activity and antimicrobial properties against Vibrio vulnificus and Micrococcus luteus. The 2,2’-Diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and total phenolic compounds (TPC) assay were used for determining antioxidant activity. The ethyl acetate spice extracts exhibited higher antioxidant activity as compared to water extracts, it can be sorted in the descending order of: clove > cardamom > thyme > black cardamom > black pepper > fenugreek seeds by DPPH assay. By FRAP assay: clove > thyme > cardamom > black cardamom > fenugreek seeds > black pepper and by TPC assay: clove > thyme > cardamom > fenugreek seeds > black cardamom > black pepper. The antimicrobial activity was screened by disk diffusion assay. Only clove and cardamom displayed antimicrobial activity at increasing concentrations in both water and ethyl acetate extracts. Clove displayed the highest 12 mm inhibition zone against V. vulnificus and 14 mm inhibition zone against M. luteus in both water and ethyl acetate extracted spices at highest concentration. Thus, clove and cardamom can be supplemented for both nutritional purposes and preservation of foods.   Key words: Spices, water extraction, solvent extraction, DPPH, FRAP, TPC, antimicrobial activity.