Influence of quercetin-rich onion peel extracts on adipokine expression in the visceral adipose tissue of rats

We examined the effects of quercetin-rich onion peel extract supplementation on adipokine expressions from adipose tissues in a diet-induced obese animal model. Male Sprague-Dawley rats (n = 24) were randomly assigned into control (n = 8), high fat diet (HF, n = 8) and high fat diet with onion peel extract (HFOE, n = 8). After 8 weeks, serum biochemical parameters, weights of adipose tissues (epididymal, perirenal and mesenteric fats) and adipokine mRNA levels (adiponectin, IL (interleukin)-6 and visfatin) along with PPAR (peroxisome proliferator-activated receptor) γ2 from adipose tissues were measured. After the 8 week supplementation, mesenteric fat weights were lower in the HFOE group than the HF group (p<0.05). Adiponectin mRNA levels (mesenteric fats) were remarkably higher in the HFOE group than the other groups (p<0.05 for both). Levels of PPARγ2 mRNA (mesenteric fats) were significantly higher in the HF group (p<0.05) than those in the control group, but those in the HFOE group were not different from those in the control group. The IL-6 mRNA levels (perirenal and mesenteric fats) were higher in the HF and HFOE groups, but those in the HFOE group were slightly lower than those in the HF group. In conclusion, quercetin-rich onion peel extract supplementation influenced adipokine expressions, particularly from mesenteric fat, addressing the modulatory effect of this substance on obesity-induced inflammation.