Effects of a Citrus depressa Hayata (shiikuwasa) extract on obesity in high-fat diet-induced obese mice

Citrus depressa Hayata (commonly known as shiikuwasa) is cultivated in the northern areas of Okinawa, Japan, and used as a juice. In this study, we examined the anti-obesity effects and mechanism of action of shiikuwasa peel extract (SE) using high-fat diet (HFD)-induced obese mice. Mice were fed a low-fat diet (LFD), HFD or HFD containing 1% or 1.5% (w/w) SE (HFD + 1 SE and HFD + 1.5 SE, respectively) for 5 weeks. The body weight gain and white adipose tissue weight were significantly decreased in the HFD + 1.5 SE group compared with the HFD group. The plasma triglyceride and leptin levels were also significantly reduced in the HFD + 1.5 SE group compared with the HFD group. Histological examinations showed that the sizes of the adipocytes were significantly smaller in the HFD + 1.5 SE group than in the HFD group. The HFD + 1.5 SE group also showed significantly lower mRNA levels of lipogenesis-related genes, such as activating protein 2, stearoyl-CoA desaturase 1, acetyl-CoA-carboxylase 1, fatty acid transport protein and diacylglycerol acyltransferase 1, than the HFD group. These results suggest that the anti-obesity effects of SE may be elicited by regulating the expressions of lipogenesis-related genes in white adipose tissue.