A GARLIC EXTRACT PROTECTS FROM ULTRAVIOLET B (280–320 nm) RADIATION‐INDUCED SUPPRESSION OF CONTACT HYPERSENSITIVITY

Abstract

Lyophilized aged garlic extract has been incorporated at concentrations of 0.1%, 1% and 4% by weight into semipurified powdered diets and fed to hairless mice. Under moderate UVB exposure conditions resulting in 58% suppression of the systemic contact hypersensitivity response in control-fed mice, a dose-responsive protection was observed in the garlic-fed mice; contact hypersensitivity in the UVB-exposed mice fed 4% garlic extract was suppressed by only 19%. If the UVB exposure was replaced by topical application of one of a series of lotions containing increasing concentrations of cis-urocanic acid, a dose-responsive suppression of contact hypersensitivity was demonstrated in control-fed mice (urocanic acid at 25, 50, 100 and 200 micrograms per mouse resulting in 22-46% suppression). Mice fed a diet containing 1% aged garlic extract were partially protected from cis-urocanic acid-induced suppression of contact hypersensitivity, with greater protection from the lower concentrations of urocanic acid. Mice fed a diet containing 4% aged garlic extract were protected from all concentrations of urocanic acid. The results indicate that aged garlic extract contains ingredient(s) that protect from UVB-induced suppression of contact hypersensitivity and suggest that the mechanism of protection is by antagonism of the cis-urocanic acid mediation of this form of immunosuppression.

Heme oxygenase induction mediates the photoimmunoprotective activity of UVA radiation in the mouse

“…First, systemic photoimmunosuppression via cis-UCA may depend on oxidative reactions, because a variety of antioxidants have been found to be photoimmunoprotective (15)(16)(17)(18)(19). Thus oxidant states, whether arising as a result of UVB or UVA …”

“…Whether ROS play a part in photoimmunosuppression is not clear, although high levels of polyunsaturated fatty acids incorporated into the epidermal lipids certainly predispose hairless mice to immunosuppression by UV radiation (14) and would be a prime source of ROS formation after UV irradiation. Furthermore, photoimmunoprotection by antioxidants such as vitamin E (15), green tea polyphenols (16), garlic (17), carnosine (18), and vitamin C (19), in studies where either UVB or cis-UCA was the immunosuppressive inducer, also suggest that oxidant states play a role.…”

Eggshell Quality, Eggshell Structure and Small Intestinal Histology in Laying Hens Fed Dietary Pantoea-6®and Plant Extracts

“…The mechanisms of garlic have been accredited to its effective antioxidant action (Yang et al, 1993), and its ability to stimulate immunological responsiveness (Reeve et al, 1993). Ramakrishna et al (2003) reported that garlic supplementation probably enhanced the activities of the pancreatic enzymes and provided a micro-environment for better nutrient utilisation in rats.…”

Garlic as an anti‐fatigue agent

“…Many in vitro studies and clinical studies have shown that natural foods or components derived from plants stimulate or regulate the immune response, or exert an anti-stress effect [34]. Immunomodulation effects of garlic have been reported to inhibit the decrease of spleen weight and spleen cell number caused by psychological stress [35], to enhance natural killer activity [36], and to suppress contact hypersensitivity [37]. It is also known that influenza or infection can have a marked effect on the immune system, leading to fatigue.…”