Effect of Garlic Oil on Hepatic Arachidonic Acid Content and Immune Response in Rats

This study examined the arachidonic acid metabolism and immune response in rats administered orally (p.o.) with either garlic oil (GO), diallyl disulfide (DADS) (200 mg/kg of body weight), or corn oil (control) three times a week for 7 weeks. Both GO and DADS were found to modify the hepatic membrane fatty acid composition: the linoleic acid was increased, and the arachidonic acid was decreased (P < 0.05). GO but not DADS suppressed the Δ6 desaturase activity (P < 0.05). Neither treatment affected the phospholipase A2 activity or plasma prostaglandin E2 level. GO increased the spleen/body weight ratio (P < 0.05) and enhanced concanavalin A-stimulated splenocyte proliferation. However, the systemic contact hypersensitivity response as detected by the extent of ear swelling was suppressed by 74% in the GO-treated rats (P < 0.05). The findings indicate that GO inhibits Δ6 desaturase activity and changes membrane arachidonic acid content, both of which show immunomodulatory potential.