Roasted barley extract (RBE, "Mugicha") is a traditional Japanese beverage reported to improve blood viscosity and affect food functionality. RBE is suggested to contain 2,5-diketopiperazines, which are the functional component with neuroprotective and immunostimulatory effects that are produced in food through roasting. In this study, we investigated the effects of RBE on blood circulation, both clinically and in rats. At first, we confirmed five 2,5-diketopiperazine derivatives in RBE by LC-MS analysis. Secondarily, we revealed that RBE affects blood flow in the rat tail and compared the efficacy on rat tail blood flow among five 2,5-diketopiperazines in RBE. Especially, cyclo(d-Phe-l-Pro) was the most effective in increasing blood flow in the rat tail. We also researched the mechanism of cyclo(d-Phe-l-Pro) with rat aorta study. As a result, we confirmed that cyclo(d-Phe-l-Pro) has an effect on vasodilatation through the release of nitric oxide in the vascular endothelium. Finally, we also confirmed that RBE affects cutaneous blood flow and increases skin temperature in humans.
SummaryBrewer's yeast cell wall (BYC) is a valuable foodstuff that prevents constipa tion in rats. In this study, the effects of yogurt supplemented with brewer's yeast cell wall (BYC-Y) on constipated male Sprague-Dawley rats induced by loperamide (2 mg/kg body weight) were investigated. The preventive effect of BYC-Y on experimentally constipated rats was examined and compared with that of nonfiber diet (Control) and standard yogurt (Yogurt) as the control diets. The number of feces and fecal dry weight were greater in rats fed with BYC-Y than in those fed with Control or Yogurt. Moreover, the effect of BYC on the improvement of cecal microflora in constipated experimental model rats was evaluated. The number of Lactobacillus, Eubacterium, and total anaerobes per unit cecal contents increased (p<0.03) as a result of BYC ingestion. These findings indicate that BYC-Y or BYC is effective for the alleviation of constipation and bowel environment.
Oxygen transportation and regulation of some physiological processes are facilitated by blood flow. Furthermore, blood flow is regulated by various factors such as nitric oxide (NO) and the autonomic nerve system. In modern life, many people suffer from chilliness (hiesho) because of mental stress and an excessive use air-conditioning systems, which induces vasoconstriction in the peripheral skin. In this study, we focused on pyrazine derivatives, particularly compounds that are used as food flavoring materials, and investigated their effects on vascular function and blood flow. We examined the vasodilatory effect of pyrazine derivatives in the rat thoracic aorta and found 2-ethylpyrazine (2-EP) to be the most active pyrazine compound. Additionally, we found that 2-EP induces vasodilatation through the activities of endothelium-derived relaxing factors. 2-EP activates NO synthesis through the effect of endothelial NO synthase in the endothelium. As a result, cyclic GMP levels rise in smooth muscle cells and vasodilatation is induced. We also confirmed that 2-EP increases peripheral blood flow in rats. From these results, we concluded that 2-EP induces vasodilatation by inducing the release of NO and increasing peripheral blood flow.
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