Comparison of the lipid-lowering effects of nicotinic acid and 2,5-dimethylpyrazine in rats

摘要

It has been known that nicotinic acid (NA), which is found in roasted coffee, binds to G protein-coupled receptor, GPR109A or HM74, on adipocytes, resulting in decreasing plasma non-esterified fatty acid (NEFA). A drawback of lipid-lowering therapy by NA comes from a rebound phenomenon found in plasma NEFA concn. The compound 2,5-dimethylpyrazine (2,5-DMP), one of the Maillard reaction products, is known to be metabolized in the liver to 5-methylpyrazinoic acid, which binds to GPR109A as well as NA. It was previously reported that 2,5-DMP has an NEFA-lowering effect in rats. This study compared the effect of 2,5-DMP with that of NA on blood concn. of NEFA in rats. The most characteristic feature of NA was found in the rebound phenomenon that was not observed in 2,5-DMP. Co-administration of 2,5-DMP with NA did not show the rebound, resulting in continuous low concn. of plasma NEFA. Although the amount of 2,5-DMP in coffee is very low, many kinds of Maillard reaction products such as 2,5-DMP are found in roasted coffee. It is also reported that some Maillard reaction products have NEFA-lowering effects. Therefore, it is suggested that 2,5-DMP and other Maillard reaction products may be useful to suppress the 'NEFA rebound' induced by NA.