Free-radical scavenging capacity and antioxidant properties of some selected onions (Allium cepa L.) and garlic (Allium sativum L.) extracts

Benkeblia, N.

Brazilian Archives of Biology and Technology 48(5): 753-759

2005


ISSN/ISBN: 1516-8913
DOI: 10.1590/s1516-89132005000600011
Accession: 004433031

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Abstract
The radical scavenging activity (RAS), chain-breaking activity, hydrogen-peroxide-scavenging activity, reducing capacity and total phenolics contents of 4 types of onion (green, yellow, red and purple onion) and garlic were investigated. The total phenolics content varied from 30 (green onion) to 49 mg 100 g-1 fresh weight (garlic). The garlic extract showed the highest RAS, while green onion showed the lowest. The chain-breaking activity of the green onion extract was higher (0.48) than that of the garlic extract (0.029). The chain-breaking activities of yellow, red and purple onion extracts were 0.19, 0.048 and 0.032 respectively; heating at 90 degrees C for 3 h increased this activity. The low ability of the green onion extract to scavenge hydrogen peroxide was observed (35%). The ability of the other onion extracts and garlic extract to scavenge hydrogen peroxide was high (60-90%). The reducing capacity was lowest for the green onion extract (18%) and highest for the garlic extract (196%). Highly significant correlations were observed between the total phenolics content and reducing power, hydrogen-peroxide-scavenging activity and chain-breaking activity of the extracts.