EFFECT OF METHANOL EXTRACT OF CABBAGE TREE (Anthocleista djalonensis A. Chev.) ON TRITON WR-1339-INDUCED HYPERLIPIDEMIA IN WISTAR RATS

Abstract

Hyperlipidemia, a major risk factor of atherosclerotic cardiovascular diseases (ASCVD) is a growing problem especially in developing countries. This research evaluated the protective property of aqueous methanol extract of Anthocleista djalonensis leaf (ADL) in triton-induced hyperlipidemia. Phytochemical evaluation, gas chromatography mass spectrometry (GC-MS) analysis and in vitro antioxidant ability of ADL were assessed. Hyperlipidemia was induced in male Wistar rats with a single dose of Triton WR-1339 (200 mg/kg) intraperitoneally with or without post treatment with ADL (200, 400 and 600 mg/kg) or rosuvastatin® (10 mg/kg) for 14 consecutive days. Total cholesterol (TC), triacylglycerol (TG), low density lipoprotein-cholesterol, (LDL-c), very low density lipoprotein-cholesterol (VLDL-c), high density lipoprotein-cholesterol (HDL-c), coronary risk index (CRI), atherogenic index (AI), electrolytes (sodium, potassium and calcium), creatine kinase (CK-MB), gamma glutamyl transferase activity (GGT), lactate dehydrogenase (LDH), alanine amino transferase (ALT), aspartate amino transferase (AST), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase, reduced glutathione (GSH), ferric reducing antioxidant power (FRAP), lipid peroxidation (LPO), and protein carbonyls (PCO) were evaluated. Histopathological evaluation of liver and heart tissues were also carried out. Docking analyses and molecular dynamics simulations to gain insights into the interaction mechanisms of ligand (stigmasterol) and oxidosqualene cyclase were carried out. In addition, mRNA expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoAR), proprotein convertase subtilisin/kexin type 9 (PCSK9), rho-kinase1 (RHO) and geranyl geranyl pyrophosphate synthase (GGPPS) were evaluated. Phytochemical investigation revealed the presence of tannins, flavonoids, saponins, cardiac glycosides, anthraquinones, terpenoids and steroids. GC-MS analysis revealed the presence of twenty six phytochemicals consisting of sterol esters, unsaturated fatty acids, triterpenes and saturated fatty acids. Total tannin, phenolic, and flavonoid contents, and total antioxidant capacity of the extract were 192.24±6.06 mg/g catechin, 78.71±3.03 mg/g gallic acid, 154.67±1.77 mg/g quercetin, and 112.33±4.50 mg/g ascorbic acid equivalents respectively. ADL demonstrated appreciable in vitro antioxidant capacity and radical scavenging ability compared with reference standards. In the in vivo experiment, triton caused deranged lipid profile, electrolyte and redox imbalance as well as alterations in the activities of cardiac and hepatic enzymes. Post-treatment with ADL resulted in significant (p<0.0001) improvement in the altered biochemical parameters (lipid profiles, electrolytes and hepatic enzymes) in the serum. Furthermore, ADL significantly (p<0.0001) restored cardiac and hepatic antioxidant status by increasing GPx, SOD and catalase activities; concentrations of GSH, and FRAP while reducing the levels of LPO and PCO. Docking analysis showed that stigmasterol had the highest binding energy of -12.9 Kcal/mol among the identified phytochemicals and the simulated complexes revealed stability and ligand remaining inside the binding pocket. ADL also mitigated structural derangement caused by triton in cardiac and hepatic tissues. Also, there was significant up-regulation of genes associated with cholesterol biosynthesis and metabolism (HMGCoAR, RHO, PCSK9, and GGPPS). ADL significantly (p<0.0001) down regulated arterial and hepatic HMGCoAR, RHO, PCSK9 and GGPPS expressions in animals administered with triton. In conclusion, ADL demonstrated antioxidant and anti-hyperlipidemic properties that could be ascribed to its constituent phytochemicals. The mechanism of action of ADL involves down-regulation of genes associated with cholesterol metabolism.