AbstractThe ability of the following aqueous garlic extracts to scavenge hypochlorous acid (HOCl) was studied: (a) unheated extract of raw garlic (RG), (b) heated extract of raw garlic (HRG), (c) extract of boiled garlic cloves (BG) and (d) extract of microwave‐treated garlic cloves (MG). The HOCl scavenging activity was evaluated following changes in the absorption spectrum of catalase (370–450 nm). RG, HRG and BG scavenged HOCl in a concentration‐dependent way: the IC50 (mg/mL) values for RG, HRG and BG were 0.339 ± 0.028, 0.632 ± 0.030 and 0.690 ± 0.031, respectively. The HOCl scavenging ability of garlic was significantly decreased when garlic cloves or the extract of raw garlic were heated (BG and HRG, respectively); this scavenging ability was eliminated when garlic was subjected to microwave heating (MG). The IC50 value for the reference compound, ascorbic acid, was 0.500 ± 0.049 mg/mL. In summary, raw garlic concentration‐dependently scavenged HOCl; this ability was eliminated in extracts of microwave‐treated garlic cloves but not in heated extracts of raw garlic or extracts of boiled garlic cloves. Copyright © 2007 John Wiley & Sons, Ltd.