Preventive and ameliorating effects of citrus d-limonene on dyslipidemia and hyperglycemia in mice with high-fat diet-induced obesity

d-limonene is a major constituent in citrus essential oil, which is used in various foods as a flavoring agent. Recently, d-limonene has been reported to alleviate fatty liver induced by a high-fat diet. Here we determined the preventive and therapeutic effects of d-limonene on metabolic disorders in mice with high-fat diet-induced obesity. In the preventive treatment, d-limonene decreased the size of white and brown adipocytes, lowered serum triglyceride (TG) and fasting blood glucose levels, and prevented liver lipid accumulations in high-fat diet-fed C57BL/6 mice. In the therapeutic treatment, d-limonene reduced serum TG, low-density lipoprotein cholesterol (LDL-c) and fasting blood glucose levels and glucose tolerance, and increased serum high-density lipoprotein cholesterol (HDL-c) in obese mice. Using a reporter assay and gene expression analysis, we found that d-limonene activated peroxisome proliferator-activated receptor (PPAR)-α signaling, and inhibited liver X receptor (LXR)-β signaling. Our data suggest that the intake of d-limonene may benefit patients with dyslipidemia and hyperglycemia and is a potential dietary supplement for preventing and ameliorating metabolic disorders.