Comparative study on the effects of apple peel polyphenols and apple flesh polyphenols on cardiovascular risk factors in mice.

Apple consumption has been demonstrated to be associated with reduced risk of cardiovascular disease, and the beneficial effect is probably due to the polyphenols in apple. Here, we for the first time evaluated and compared the in vivo effects of the polyphenolic extracts of apple peels (PAP) and apple fleshes (PAF) on blood pressure, vascular endothelial function, lipid metabolism and insulin resistance. A high-fat and high-fructose (HFHF) diet was used to cause cardiovascular disorders in mice, with blood pressure, serum ET-1, TC, TG, LDL-C, glucose and insulin levels increased, and serum NO and HDL-C levels decreased. Mice administered with 250 mg/kg of PAP and PAF for 28 days showed lower blood pressure, improved endothelial function, ameliorated lipid homeostasis and decreased insulin resistance compared with HFHF-fed mice. Furthermore, PAP exhibited much more potent cardioprotective effects than PAF in mice. Quantification and phenolic profile analysis showed that PAP contained remarkably higher amount of total phenolics and total flavonoids than PAF, and this may be the reason for the relatively stronger efficacy of PAP. This study demonstrates that apple polyphenols possess potential cardioprotective effects, and suggests that apple, especially apple peel, may be excellent source for exploration of preventive agents against cardiovascular disorders.