ABSTRACT: Citri grandis exocarpium (Citri grandis) has been consumed by human beings for fifteen hundred years. It is commonly consumed as a health drink and dietary supplement in China. However, its nutritional and healthcare functions are still not fully understood. Objective: Our previous study found that oral administration of Citri grandis extract can significantly decrease the blood lipid levels of hyperlipidemic mice fed a high-fat diet. The aim of this study was to confirm the preventative effects of Citri grandis extract against atherosclerosis. Methods: Atherosclerotic lesion models were induced in HUVECs and apoE-/- C57BL/6J mice. ApoE-/- mice fed a high-fat diet were orally administered Citri grandis extract (0.4, 0.8, and 1.6 g/kg/d BW) and Simvastatin (1 mg/kg/d BW) on the first day of model establishment. After a 16-week treatment, serum samples and aorta and liver tissues were collected. Observation of pathological changes in aortic and liver tissues was performed using a light microscope with oil red O, H&E, Masson's trichrome staining, and TEM. Biochemical detection was employed to determine the serum levels of TC, TG, LDL-C, and HDL-C as well as the activities of AST and ALT. In addition, expression studies of TGF-β, PI3K, AKT1, PPAR-γ, LXR-α, and ABCA1 were performed via qPCR and Western blot analysis. Results: Compared with cholesterol-induced HUVECs, Citri grandis extract significantly enhanced cell viability, attenuated the morphological changes in HUVECs, and reduced LDH release. Furthermore, after treatment with Citri grandis extract, the levels of TC, TG, and LDL-C significantly decreased in the atherosclerosis model apoE-/- mice after 16 weeks, and aortic plaque, lipid deposition, and endothelial injury were obviously ameliorated. The mRNA and protein expression of TGF-β, PPAR-γ, LXR-α, and ABCA1 in aortic and liver of atherosclerosis apoE-/- mice were upregulated (p < 0.05, p < 0.01), while those of PI3K and Akt1 were suppressed (p < 0.05, p < 0.01). Conclusions:Citri grandis extract can significantly decrease the high circulating lipid levels and the liver lipid deposition of high-fat-diet-fed apoE-/- mice and reduce aorta lipid accumulation and atherosclerotic plaques by regulating the expression of TGF-β1, PI3K, AKT1, PPAR-γ, LXR-α, and ABCA1. Citri grandis extract can be used as a healthcare dietary supplement for the prevention of abnormal lipid metabolism and atherosclerosis.
