An in vitro and in vivo study of a 4-herb formula on the management of diet-induced metabolic syndrome

Abstract

Background: Metabolic syndrome is the cluster of risk factors that leads to increased episodes of cardiovascular disease (CVD). These risk factors include but are not limited to obesity, non-alcoholic fatty liver (NAFLD), dyslipidemia, and type 2 diabetes. Since the pathogenesis of metabolic syndrome has multiple metabolic origins, there is no single treatment for it. Pharmacological approaches consist of separate drugs which target at individual risk factors which pose various side effects. Functional foods or nutraceuticals which have potentially important anti-obesity properties have thus attracted great attention. Schisandrae Fructus is a Chinese herb traditionally used as a liver tonic. Silymarin, an extract of the milk thistle (Silybum marianum), is a dietary supplement that is widely used in western society for the prevention and treatment of liver problems. Crataegus Fructus (hawthorn) is traditionally used to promote digestion and dissipate food stagnation. Momordica charantia (bitter melon) is traditionally used for treatment of diabetes in Ayurvedic Medicine. Hypothesis/Purpose: We aimed to develop a multi-targeted herbal formula to target on the multiple risk factors of metabolic syndrome using individual herbs. This proposed herbal formula include sylimarin and Schisandrae Fructus, for NAFLD; Crataegus Fructus for obesity and hyperlipidemia; and Momordica charantia for hyperglycemia. Study Design and Methods: For in vitro study, we carried out insulin-induced 3T3-L1 adipocytes differentiation and fluorescent tagged cholesterol-treated Caco-2 cell assay to study for adipogenesis and cholesterol uptake into Caco-2 cells, respectively. Oleic acid-induced HepG2 cell assay was used to study for oleic acid-induced fatty liver, and brush border membrane vesicles (BBMV) assay was used to study for glucose uptake from the gut. For in vivo study, we performed an 8-week and a 12-week treatment studies, with each study comprising of 4 groups of C57Bl/6 male mice given: (i) Normal-chow diet; (ii)–(iv) High-fat diet (contains 21% fat and 0.15% cholesterol). After the initial 8 weeks of normal chow or high-fat diet feeding to induce obesity, animals were given: (i) Normal-chow diet; (ii) High-fat diet; (iii) High-fat diet + 2% herbal formula; or (iv) High-fat diet + 4% herbal formula as treatment for another 8 weeks or 12 weeks. Results: Our in vitro results suggested Crataegus Fructus aqueous extract exerted potent inhibitory effects on 3T3-L1 preadipocytes differentiation and cholesterol uptake into Caco-2 cells. Schisandrae Fructus aqueous extract and milk thistle exerted inhibitory effects on oleic acid-induced fatty liver in HepG2 cells. Momordica charantia extract on the other hand, exerted significant inhibitory effect on glucose uptake into BBMV. Our in vivo results showed that our herbal formula exhibited a trend to reduce diet-induced increase in body weight and fat pad mass (epididymal, perirenal and inguinal fat); and significantly reduced diet-induced increase in liver weight, liver lipid, and plasma lipid dose-dependently. Besides, high-fat diet induced a significant reduction in adiponectin level which was significantly improved by herbal formula supplementation at 4%. There was however no significant effect of the herbal formula on diet-induced increase in plasma glucose or insulin levels at either dose. Herbal formula also significantly reduced diet-induced inflammation in the liver at both doses. Conclusions: Taken together, these data suggested the potential of our novel multi-targeted herbal formula to be used as a therapeutic agent for diet-induced metabolic syndrome, with special emphasis on NAFLD.