Polyphenol-rich peach (Prunus persica L.) by-product exerts a greater beneficial effect than dietary fiber-rich by-product on insulin resistance and hepatic steatosis in obese rats

Peach juice by-product (PJBP) can prevent complications of obesity due to its high content of polyphenols and dietary fiber. This study aimed to evaluate the effect of a polyphenol-rich (PR-PJBP) and a dietary fiber-rich (DFR-PJBP) peach juice by-product on insulin resistance and hepatic steatosis in obese rats. Animals were fed with high fat and fructose diet (HFF) and supplemented with PR-PJBP and DFR-PJBP for eighteen weeks. PR-PJBP produced the greatest hypoglycemic effect by improving insulin resistance, increasing hepatic glycogen content, and decreasing hepatic PEPCK activity. Likewise, PR-PJBP decreased serum triglycerides levels, ameliorating hepatic steatosis, decreasing hepatic expression of Srebp1 and Fasn, and increasing hepatic Cpt1 expression. These results suggest that polyphenols from PJBP exert a greater beneficial effect on obesity-related complications than dietary fiber. These effects were associated with caffeoylquinic, p-coumaroylquinic and 4-feruloylquinic acids, and kaempferol derivatives. PR-PJBP could be used as an ingredient for the elaboration of functional foods.