Abstract
Elevated serum cholesterol levels, either associated or not with increased triglycerides, represent a risk of developing vascular injury, mostly leading to atherothrombosis-related diseases including myocardial infarction and stroke. Natural products have been investigated in the last few decades as they are seen to offer an alternative solution to counteract cardiometabolic risk, due to the occurrence of side effects with the use of statins, the leading drugs for treating hyperlipidemias. Red yeast rice (RYR), a monacolin K-rich natural extract, has been found to be effective in counteracting high cholesterol, being its use accompanied by consistent warnings by regulatory authorities based on the potential detrimental responses accompanying its statin-like chemical charcateristics. Here we compared the effects of RYR with those produced by bergamot polyphenolic fraction (BPF), a well-known natural extract proven to be effective in lowering both serum cholesterol and triglycerides in animals fed a hyperlipidemic diet. In particular, BPF at doses of 10 mg/Kg given orally for 30 consecutive days, counteracted the elevation of both serum LDL cholesterol (LDL-C) and triglycerides induced by the hyperlipidemic diet, an effect which was accompanied by significant reductions of malondialdehyde (MDA) and glutathione peroxidase serum levels, two biomarkers of oxidative stress. Furthermore, the activity of BPF was associated to increased HDL cholesterol (HDL-C) levels and to strong reduction of Proprotein convertase subtilisin/kexin type 9 (PCSK9) levels which were found increased in hyperlipidemic rats. In contrast, RYR at doses of 1 and 3 mg/Kg, produced only significant reduction of LDL-C with very poor effects on triglycerides, HDL-C, glutathione peroxidase, MDA and PCSK9 expression. This indicates that while BPF and RYR both produce serum cholesterol-lowering benefits, BPF produces additional effects on triglycerides and HDL cholesterol compared to RYR at the doses used throughout the study. These additional effects of BPF appear to be related to the reduction of PCSK9 expression and to the antioxidant properties of this extract compared to RYR, thereby suggesting a more complete protection from cardiometabolic risk.
Highlights
Hypercholesterolemia, either associated or not to increased triglyceride serum levels, has been clearly shown to represent one of the key players in the development of atherosclerosis-associated vascular disorders including coronary artery disease and stroke [1,2]
Administration of hyperlipidemic diet in rats (Group 2) produced, compared to control group (Group 1) an elevation of serum levels of total cholesterol, low-density lipoprotein cholesterol (LDL-C) (Table 1) and an elevation of serum paraoxonase activity, MDA and proprotein convertase subtilisin/kexin type 9 (PCSK9) expression, an effect accompanied by reduction of HDL cholesterol (HDL-C) levels and of glutathione peroxidase, an endogenous antioxidant enzyme
bergamot polyphenolic fraction (BPF), according to previous evidence, significantly reduces the levels of serum total and LDL-C, an effect associated to reduced triglycerides, MDA, PCSK9 and paraoxonase activity
Summary
Hypercholesterolemia, either associated or not to increased triglyceride serum levels, has been clearly shown to represent one of the key players in the development of atherosclerosis-associated vascular disorders including coronary artery disease and stroke [1,2]. This was achieved by means of extensive use of very effective drugs such as the statins, which reduce endogenous biosynthesis of cholesterol, via inhibition of hydroxy-3-methylglutaryl-CoA reductase (HMGCoA reductase), the key enzyme of the pathway generating cholesterol from acetyl-CoA [6,7,8] This class of drugs, due to their widespread activities in protecting vascular tissues, (anti-proliferative effects, atherosclerotic plaque stabilizing properties, reduction of vascular inflammatory biomarkers, etc.), has been found able to reduce hospitalization and mortality in high-risk atherosclerotic patients [6,7]. Based on the occurrence of these and other side effects, the use of statins in low-risk subjects is still controversial and alternative and more safe treatments for lowering serum cholesterol have been suggested in the last few decades, including nutraceutical supplementation by means of products able to inhibit HMGCoA reductase [15,16]
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