Effects of garlic preparations on superoxide production by phorbol ester activated granulocytes

Sulfur containing constituents of garlic are considered responsible for con veying the antioxidative properties of garlic preparations. The radical sca venging properties of garlic preparations against oxygen radicals, specific ally their ability to inhibit the formation of superoxide anions, were inve stigated using human granulocytes activated with 10 nM phorbol myristyl ace tate (PMA). A garlic powder preparation inhibited the production of superox ide with a calculated IC,, of 390 mu/ml. An 8-10% alliin enriched garlic ex tract (alliinase inactivated) did not inhibit superoxide production even at concentrations as high as 1000 mu g/ml. When the extract was mixed with ga rlic powder (90% garlic powder, 10% garlic extract), there was a clear inhi bition of superoxide production with an IC50 value of 235 mu g/ml. An even stronger inhibitory effect could be achieved when garlic powder was added t o garlic extract (10% garlic powder, 90% extract, IC50 = 160 mu g/ml). Thes e experimental results suggest that the alliin metabolite allicin may be re sponsible for the oxygen radical scavenging properties of garlic.