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The sesquiterpene zerumbone, isolated from the rhizome of Zingiber zerumbet Sm., besides its widespread use as a food flavouring and appetiser, is also recommended in traditional medicine for the treatment of several ailments. It has attracted great attention recently for its effective chemopreventive and therapeutic effects observed in various models of cancer. To assess the zerumbone safety profile, a pharmacology study designed to flag any potential adverse effect on vasculature was performed. Zerumbone was tested for vasorelaxing activity on rat aorta rings and for L-type Ba2+ current blocking activity on single myocytes isolated from the rat-tail artery. The spasmolytic effect of zerumbone was more marked on rings stimulated with 60 mM than with 30 mM K+ (IC50 values of 16 μM and 102 μM, respectively). In the presence of 60 mM K+, zerumbone concentration-dependently inhibited the contraction induced by the cumulative addi tions of Ca2+, this inhibition being inversely related to the Ca concentration. Phenylephrine-induced contraction was inhibited by the drug, though less efficiently and independently of the presence of an intact endothelium, without affecting Ca2+ release from the intracellular stores. Zerumbone inhibited the L-type Ba2+ current (estimated IC50 value of 458.7 μM) and accelerated the kinetics of current decay. In conclusion, zerumbone showed an overall weak in vitro vasodilating activity, partly attributable to the blocking of the L-type Ca2+ channel, which does not seem to represent, however, a serious threat to its widespread use. [ABSTRACT FROM AUTHOR]

Zingiber zerumbet (L) Smith (Zingiberaceae), commonly known as the pinecone or shampoo ginger, is distributed in many parts of Asia. It has been demonstrated that the aqueous extract of Z. zerumbet exerted a potential blood glucose lowering effect in normoglycemic and streptozotocin-induced hyperglycemic rats. The present study was undertaken to clarify whether the ethanol extract of Zingiber zerumbet (EEZZ) is effective in improving insulin resistance. Insulin resistance was induced in rats by feeding a high-fructose diet for six weeks. Thereafter, rats were maintained on the same diet and treated with oral EEZZ or pioglitazone once daily for eight weeks. At the end of treatment, the degree of basal insulin resistance was measured by homeostasis model assessment (HOMA-IR). Insulin sensitivity was calculated using the composite whole body insulin sensitivity index (ISIcomp). Protein expression was evaluated by immunoblotting. Phytochemicals in EEZZ were determined through liquid chromatography-tandem mass. Not only curcumin but also quercetin and kaempferol were abundant in EEZZ. EEZZ (300mg/kg/day) displayed similar characteristics to pioglitazone (20mg/kg/day) in reducing HOMA-IR and elevating ISIcomp aswell as enhancing hepatic glycogen accumulation. Elevated glycosylated hemoglobin levels and hyperinsulinemia were ameliorated by EEZZ. Further, EEZZ enhanced the action of insulin on muscle glucose transporter subtype 4 translocation and attenuated hepatic phosphoenolpyruvate carboxykinase expression. This study suggests that EEZZ may be an ethnomedicine for improving insulin sensitivity. [ABSTRACT FROM AUTHOR]