Suppressive effect of defatted kiwi fruit seed extract on acute inflammation and skin pigmentation

Abstract

While kiwi fruit seeds are ingested with sarcocarps, biological activities associated with these seeds have not been examined. We evaluated the effects of the extract of defatted kiwi fruit seeds (KSE) on inflammation and melanin production. In a mouse writhing model stimulated by acetic acid, KSE (100-400 mg/kg) suppressed the increase in abdominal capillary permeability in a dose-dependent manner. KSE inhibited lipopolysaccharide-induced prostaglandin (PG) E2 production, but not nitric oxide (NO) production from RAW264 cells. Quercitrin and kaempferol 3-O-rhamnoside, flavonol glycosides isolated from KSE, suppressed PG E2 and NO production only at high concentrations (100μg/mL). Hence, contribution of these compounds to the inhibitory activity of KSE appeared to be low. KSE, quercitrin, and kaempferol 3 -O-rhamnoside showed inhibitory effects on tyrosinase activity and melanin production in B16 melanoma cells. However, daily oral administration of KSE (200-800 mg/kg) for 24 days did not affect melanin production induced by ultraviolet ray (UV)-B irradiation; instead, it enhanced the disappearance of pigmentation in the guinea pig skin. Consequently, KSE was found to suppress acute inflammation and enhance melanin disappearance. Although flavonol glycosides suppressed melanin production in vitro, their involvement in anti-inflammatory activity and melanin disappearance of KSE was not clarified.