Extracts of Pomelo Peels Prevent High-Fat Diet-Induced Metabolic Disorders in C57BL/6 Mice through Activating the PPARα and GLUT4 Pathway

Abstract

ObjectiveMetabolic syndrome is a serious health problem in both developed and developing countries. The present study investigated the anti-metabolic disorder effects of different pomelo varieties on obese C57BL/6 mice induced by high-fat (HF) diet.DesignThe peels of four pomelo varieties were extracted with ethanol and the total phenols and flavonoids content of these extracts were measured. For the animal experiment, the female C57BL/6 mice were fed with a Chow diet or a HF diet alone or supplemented with 1% (w/w) different pomelo peel extracts for 8 weeks. Body weight and food intake were measured every other day. At the end of the treatment, the fasting blood glucose, glucose tolerance and insulin (INS) tolerance test, serum lipid profile and insulin levels, and liver lipid contents were analyzed. The gene expression analysis was performed with a quantitative real-time PCR assay.ResultThe present study showed that the Citrus grandis liangpinyou (LP) and beibeiyou (BB) extracts were more potent in anti-metabolic disorder effects than the duanshiyou (DS) and wubuyou (WB) extracts. Both LP and BB extracts blocked the body weight gain, lowered fasting blood glucose, serum TC, liver lipid levels, and improved glucose tolerance and insulin resistance, and lowered serum insulin levels in HF diet-fed mice. Compared with the HF group, LP and BB peel extracts increased the mRNA expression of PPARα and its target genes, such as FAS, PGC-1α and PGC-1β, and GLUT4 in the liver and white adipocyte tissue (WAT).ConclusionWe found that that pomelo peel extracts could prevent high-fat diet-induced metabolic disorders in C57BL/6 mice through the activation of the PPARα and GLUT4 signaling. Our results indicate that pomelo peels could be used as a dietary therapy and the potential source of drug for metabolic disorders.

Ameliorative effects of lutein on non-alcoholic fatty liver disease in rats

“…SIRT1 regulates the expression of peroxisome proliferators activated receptor (PPAR)-α, a key factor in the regulation of lipid metabolism [15,16] . However, to our knowledge, there are few studies regarding the effect of lutein supplements on SIRT1 and PPAR-α.…”

“…Some studies have demonstrated that PPAR-α plays an important role in the regulation of hepatic lipid metabolism [15,32] and that the inhibition of PPAR-α might induce hepatic steatosis [33] . Thus, we tested the protein level of PPAR-α and found that HFD feeding significantly inhibited the expression of PPAR-α, and that lutein supplementation reversed such inhibition effectively.…”

“…Consistent with our results, some studies have also found that lutein may be an inducer of PPAR expression [34] . Meanwhile, SIRT1, a NAD + -dependent deacetylase, has been reported to be the upstream regulator of PPAR-α [15] , regulating lipid metabolism by activating PPAR-α [35] . However, some studies have suggested that SIRT1 is involved in regulating hepatic insulin signaling [36] and preventing insulin resistance [37] .…”

“…To further explore the underlying mechanisms of lutein in lipid metabolism, we detected the protein content of hepatic PPAR-α, a key factor in the regulation of lipid metabolism [15] . As shown in Figure 8A, HFD feeding inhibited PPAR-α protein accumulation, however lutein supplementation reversed this phenotype, especially in the high-dose group (P < 0.05).…”

Anti-obesity effect of traditional Chinese medicine and natural products

“…Ding et al found that extracts of pomelo peels blocked the body weight gain, lowered fasting blood glucose, serum total cholesterol, liver lipid levels, and improved glucose tolerance and insulin resistance, It can also lowered serum insulin levels in HF diet-fed mice (43). Panax notoginseng saponins, the principal ingredients extracted from the traditional Chinese medicinal herb Panax notoginseng, exhibited a considerable anti-obesity action, significantly increase insulin sensitivity and improve glucose homeostasis in KK-Ay mice which is clinically significant for the management of diabetes.…”