Phenolic Compounds and the Anti-Atherogenic Effect of Bee Bread in High-Fat Diet-Induced Obese Rats

Abstract

This study was undertaken to determine the phenolic compounds and the anti-atherogenic effect of bee bread in high-fat diet (HFD)-induced obese rats. The presence of phenolic compounds in bee bread was determined by liquid chromatography-mass spectrometry. Thirty-two male Sprague Dawley rats were divided into four groups, (n = 8/group); i.e., Normal (N), HFD (high-fat diet), HFD + BB (high-fat diet and 0.5 g/kg/day bee bread), and HFD + O (high-fat diet and 10 mg/kg/day orlistat) groups. After 6 weeks of the experiment, rats were sacrificed. Five phenolic compounds were identified in bee bread; namely, caffeic acid, ferulic acid, kaempferol, apigenin, and isorhamnetin. Bee bread significantly reduced Lee obesity index and levels of total cholesterol (TC), low-density lipoprotein (LDL), fatty acid synthase (FAS) activity, atherogenic index, oxidised-LDL (oxLDL), and malondialdehyde (MDA), and significantly increased aortic antioxidant activities, such as those of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Adipocyte sizes were found to be smaller in the HFD + BB group compared to the N group, and en face aortas showed an absence of atherosclerotic plaque in rats supplemented with bee bread. These changes might suggest an anti-atherogenic effect of bee bread in HFD-induced obese rats via its antioxidant and hypocholesterolaemic properties.

Keywords: anti-atherogenic; bee bread; obese; phenolic compounds.

Figure 1

Macroscopic findings of aortic arch segment in Oil Red O staining under a stereomicroscope. Aortic arch segments from N (a), HFD + BB (c), and HFD + O (d) groups show intact aorta arch segments without atherosclerotic plaque. However, the segment from HFD group shows the presence of atherosclerotic plaques (yellow arrow) in the aortic arch (b). N, normal; HFD, high fat diet; HFD + BB, high-fat diet and 0.5 g/kg bee bread; HFD + O, high-fat diet and 10 mg/kg orlistat.

Figure 1

Macroscopic findings of aortic arch segment in Oil Red O staining under a stereomicroscope. Aortic arch segments from N (a), HFD + BB (c), and HFD + O (d) groups show intact aorta arch segments without atherosclerotic plaque. However, the segment from HFD group shows the presence of atherosclerotic plaques (yellow arrow) in the aortic arch (b). N, normal; HFD, high fat diet; HFD + BB, high-fat diet and 0.5 g/kg bee bread; HFD + O, high-fat diet and 10 mg/kg orlistat.

Figure 2

Histological findings of adipose tissue in H&E staining under light microscope. HFD group (b) has relatively larger adipocyte size compared to N group (a). Both HFD + BB (c) and HFD + O (d) groups had relatively smaller adipocyte size compared to the HFD group. N, normal; HFD, high fat diet; HFD + BB, high-fat diet and 0.5 g/kg bee bread; HFD + O, high-fat diet and 10 mg/kg orlistat. (Magnification ×200, Haematoxylin and Eosin staining).