Roles as metabolic regulators of the non nutrients, capsaicin and capsiate, supplemented to diets

Capsaicin is a pungent principle of hot red pepper and a non-nutrient. Capsaicin supplementation to high fat diet prevents fat deposit in the adipose tissue through secretion of adrenaline from the adrenal gland via activation of adrenal sympathetic nerve in rats. The chemical structure of a capsaicin analog found in non-pungent red pepper which was selected and fixed from a pungent variety was recently determined by our group to be a novel compound, capsiate. The gastrointestinal absorption and the metabolism of capsiate after oral administration in rats was studied. Capsiate rapidly disappeared from upper region of the gastrointestinal tract. It was cleaved to vanillyl alcohol and vanillic acid. The cleaved products were excreted in the urine as a conjugated complex such as glucuronide. The effect of capsiate on adrenaline secretion from the adrenal medulla of anesthetized rats was investigated. Capsiate evoked rapid and transient adrenaline secretion as dose-dependent manner. Capsazepine, a specific inhibitor of vanilloid (capsaicin) receptor subtype 1 (VR1), blocked capsiate-induced adrenaline secretion to show the participation of VR1 for this response. These results support that non-nutrients such as capsaicin and capsiate are well absorbed into blood and play important roles in regulating energy and lipid metabolism.