BSN272 Prevents Western Diet-Induced Atherosclerosis and Excess Weight Gain in ApoE/Mice

Objective: The purpose of this study was to determine whether BSN272 could prevent the development of hyperlipidemia and atherosclerosis in ApoE knockout mice fed a Western (high fat and cholesterol, high sugar) diet. Background: BSN272 is a combination drug therapy consisting of D-tagatose and polydatin. D-tagatose has been studied for the treatment of diabetes for several years and has been shown to lower glycated hemoglobin (HbA1c), to reduce cholesterol and triglycerides, as well as prevent weight gain in animals and humans. Polydatin is an antioxidant that appears to promote lipid catabolism and evidence suggests it can reduce diet-induced dyslipidemia in animals. Methods: ApoE-deficient mice were randomized to produce three groups with the same mean body weight. The mice were given the following diets for 16 weeks: Group 1 standard control diet; Group 2 Western diet (high fat, high cholesterol diet, high sucrose); Group 3 Western diet formulated with BSN272. Mice were measured for weight gain, tissue and organ weights, total serum cholesterol and triglycerides and formation of aortic atherosclerosis. Results: Treatment of ApoE mice prevented weight gain and lowered total cholesterol compared to mice on a Western diet alone. The effectiveness of BSN272 in lowering cholesterol increased over the time course of the experiment, with cholesterol steadily decreasing over the 16 weeks of treatment. Importantly, mice treated with BSN272 also showed significantly lower triglycerides than mice on the standard diet or the Western diet. The addition of BSN272 to the Western diet prevented the formation of atherosclerotic plaques compared to Western diet alone. Conclusion: BSN272 prevents the development of atherosclerosis, excess weight gain, and rise in total cholesterol and triglycerides in ApoE mice induced by a Western diet. Introduction Evidence supports a link between obesity and a spectrum of diseases including type 2 diabetes, hypertension, abnormal blood lipids (usually in the form of hyperlipidemia), and increased risk for cardiovascular disease. Hyperlipidemia is typically characterized by elevated levels of triglycerides and low-density lipoprotein (LDL) cholesterol and by low levels of high-density lipoprotein (HDL) cholesterol. This disease commonly manifests in those who are obese and those with type 2 diabetics, and is thought to be a major contributor to the increased incidence of cardiovascular disease seen in these two populations (1,2). Reduction of elevated LDL is a major drug treatment goal and has produced significant reduction in cardiovascular events in pat ients wi th cardiovascular disease and diabetes (3). In addition to lowering LDL, research has also shown that raising HDL in persons with low HDL can reduce the number of coronary events, a finding that has led to an interest in the development of drugs that can accomplish this HDL improvement (4). Elevated serum cholesterol levels have been noted in rodents (5), dogs (6), nonhuman primates (7), and humans (8) consuming a high-carbohydrate diet, particularly one including fructose and sucrose. Recent studies have provided evidence that fructose causes hyperlipidemia postprandially, both directly through the synthesis of fatty acids, and indirectly by increasing liver re-esterification of fatty acids (9). Low-density lipoprotein receptor deficient (LDLr) mice fed a high sucrose diet exhibited elevated serum LDL cholesterol concentrations and increased atherosclerosis compared to mice fed an energy-matched diet enriched in saturated fatty acids (10). D-tagatose, a naturally occurring epimer of fructose, was originally developed as a low-calorie sweetener (1.5 kcal/g compared to 4 kcal/g for sucrose) but was found to have an antihyperglycemic effect in animal and in human studies and showed promise as a treatment for type 2 diabetes and obesity (11, 12, 13). After over 10 years of animal and human studies for use as a food sweetener, D-tagatose was classified as being “generally recognized as safe (GRAS)” by the WebmedCentral > Research articles Page 2 of 21 WMC005014 Downloaded from http://www.webmedcentral.com on 04-Nov-2015, 11:40:26 AM FDA and has been used since in food and beverage products with no adverse events reported. The mechanism by which D-tagatose produces its antihyperglycemic effect in response to a meal is not clear. However, based on studies with fructose and D-tagatose, it has been proposed that D-tagatose is metabolized following a pathway that is essentially the same as that of fructose (13). After absorption from the intestine and transport to the liver, fructokinase phosphory la tes Dtaga tose to p roduce D-tagatose-1-phosphate. D-tagatose-1-phosphate can stimulate glucokinase activity (14, 15) leading to increased phosphory lat ion of g lucose to glucose-6-phosphate leading to further activation of glycogen synthase (16). There has been speculation that D-tagatose-1-phosphate can inhibit glycogen phosphory lase in the same manner that fructose-1-phosphate does (13), but this has not been directly shown. By activating glycogen synthase and possibly inhibiting glycogen phosphorylase, D-tagatose-1-phosphate increases glycogen synthesis and inhibits glycogen utilization, explaining, at least in part, the antihyperglycemic effect of the sugar. In addition to the effect on glycogen regulation, D-tagatose inhibits sucrase (17), leading to the suppression of sucrose digestion in the small intestine and inhibits the activity of maltase, at least in vitro, and could slow the digestion of starch. The net effect of the regulation of these enzymes is an increase in glycogen synthesis and storage and a decrease in glycogen utilization. In addition, D-tagatose reduces the absorption and digestion of sucrose and other carbohydrates in the small intestine. D-tagatose has been shown in both animal and human studies to have multiple effects including increase in satiety and weight control, a beneficial effect on abnormal blood lipids, a reduction in atherosclerotic plaque formation, and a reduction in blood glucose and HbA1c levels in patients with type 2 diabetes mellitus (11, 13, 18 26). In addition to its antihyperglycemic effects, D-tagatose has been found to have an effect on blood lipid levels in animals and in humans. In one study, LDL mice fed a diet in which high sucrose was replaced with an equivalent amount of D-tagatose had reduced cholesterol, triglycerides and atherosclerosis compared to mice on the diet containing sucrose (24). In a human clinical trial, patients with type 2 diabetes taking D-tagatose were found to have improved HDL levels, increasing from 30 to 41.7 mg/dL over the course of the 14 month study (20). This is interesting in light of evidence suggesting that increasing HDL levels decrease the risk of coronary events. The mechanism by which D-tagatose raises HDL is not clear, but it should be noted that these patients did lose weight during the study and this may have contributed to the improvement in HDL. In other studies, type II diabetics taking D-tagatose showed a decrease in HbA1c and serum triglycerides (11, 12). There is considerable interest in the use of trans-resveratrol and its derivatives, including polydatin, for the treatment of many human diseases (27). Extracts derived from Polygonum cuspidatum have long been a part of traditional Chinese herbal medicine being used to treat pain, fever, coughs, inflammation and a variety of other ailments (28). Polydatin, a glucoside derivative of resveratrol, is the major component of these extracts. In addition to Polygonum, polydatin has been found in wines and grapes (29-32), cocoa (33), peanuts and peanut butter (34), pistachios (35) and almonds (36). As a derivative of resveratrol, polydatin is believed to have many of the same beneficial effects but has some properties that may make i t more e f fec t ive f rom a pharmacological standpoint than resveratrol. Polydatin is structurally the same as resveratrol except that it has a glucoside group attached to the C-3 position in place of a hydroxyl group. This substitution makes polydatin more water soluble and more resistant to enzymatic breakdown than resveratrol. It is also actively taken up by cells via glucose carriers in the cell membrane instead of being passively transported like resveratrol (37, 38). These properties would suggest that polydatin would have greater bioavailability than resveratrol. Claims for the many health benefits of polydatin abound. A multitude of studies have presented evidence that polydatin has many positive health effects including anti-inflammatory (39, 40), hepatoprotective (41-44), anti-cancer (45-48), neuroprotective (39, 49-51), and cardioprotective activities (28, 52-55). Pharmacological studies and clinical practice have demonstrated that polydatin also has protective effects against shock (56, 57), ischemia/reperfusion injury (58, 59), congestive heart failure (60), endometriosis (61), and prevention of fatty liver disease and insulin resistance (62), and that it can regulate glucose and lipid metabolism (63). Polydatin has found its way into clinical trials for the treatment of hemorrhagic shock and irritable bowel syndrome (40, 64). How polydatin is able to have all of these activities is still being studied but multiple mechanisms of action are evident, including; an antioxidant, free radical-elimination mechanism (65-66), activation of protein kinase C (67, 68), suppression of NF-kappaB ( 6 8 ) , i n h i b i t i o n o f t h e a c t i v a t i o n o f WebmedCentral > Research articles Page 3 of 21 WMC005014 Downloaded from http://www.webmedcentral.com on 04-Nov-2015, 11:40:26 AM renin-angiotensin-aldosterone system and decreasing the excretion of endothelin 1, TNF-α, and angiotensin II (54), reduction of lipid peroxidation levels (37, 69), up regulation of the expression of hippocampal brain-derived neurotrophic factor (70), enhanced insulin sensitivity in the liver as shown by improved insulin receptor substrate 2 expression levels and Akt phosphorylation (63), decreasing the content of malonydialdehyde (MDA) (50), promoting the activities of total superoxide dismutase (T-SOD), catalase and glutathione peroxidase (GSH-Px) in plasma, and increasing the content of glutathione (GSH) in myocardial tissue (66), restoring decreased deacetylase sirtuin1 activity and protein expression in liver tissue following severe shock (71) and activation of sir tuin (72, 73), suppressing oxidat ive stress-induced lysosomal instability and mitochondrial injury by increasing the protein expression of SOD2