EFFECT OF SOURSOP (Annona muricata) FRUIT AND LEAF EXTRACTS ON MONOSODIUM GLUTAMATE AND DIET INDUCED OBESITY IN WISTAR RATS.

Abstract

Soursop plants (Annona muricata) are characterized by their rich content of flavonoids, polyphenols, steroids, tannins and are used in traditional medicine for the treatment of many diseases which include cancer and hypertension. This study was designed to investigate the effects of methanol extracts (fruit and leaf) of Annona muricata on monosodium glutamate-high fat diet induced obesity in Wistar rats. The extracts were quantitative and qualitative phytochemically screened and followed by evaluation of in vitro antioxidant properties, evaluation of lipid profiles, coronary risk, atherogenic risk, lipogenic genes in the adipose tissue and liver were performed. Sixty three Wistar rats (female neonates with average weight of 2.5g)were divided into 9 groups (n= 7) each. All the animals except control group (distilled water) and the groups administered the plant extracts alone received 2 mg/kg(body weight) monosodium glutamate (MSG) (i.p) every other day for 10 days. Furthermore, the MSG treated groups were fed with high fat diet (HFD) after six weeks post-treatment alongside with 100 mg/ kg body weight Nicotinic acid (standard drug) and the extracts(50-100 mg/kg b.wt) body weight while other groups were fed normal diet for 8 weeks. Their body weights were recorded throughout the experimental period. Also the levels, of their lipid parameters (triglyceride (TRIG), cholesterol (CHOL), low density lipoprotein (LDL) and high density lipoprotein (HDL), very low density lipoprotein (VLDL)), coronary risk index, atherogenic index, antioxidant enzymes (glutathione, catalase, superoxide dismutase, lipid peroxidation) and lipogenic gene expression (resistin, HMG-COA reductase, acetyl COA carboxylase, adiponectin, fatty acid binding protein) were evaluated at the end of the treatment. The phytochemical constituents of A. muricata revealed the total phenolic (635.0± 12.01 and 547± 9.11 ug/g gallic acid equivalent in leaf and fruit extracts) total flavonoids (408.5 ± 3.30and 276.0 ± 2.23ug/g quercetin equivalent in leaf and fruit extracts), total sterols (629.0 ±11.42 and 496.0 ± 5.34 ug/g cholesterol equivalents in leaf and fruit extracts) and total tannins (725.8±10.01 and 632.5± 7.45 ug/g tannic acid equivalents in leaf and fruit extracts).There were significant (P<0.05) increase in the concentrations of CHOL, TRIG, LDL,VLDL and decrease in the concentration of HDL, increase in coronary risk index and atherogenic index in the plasma of rats given high fat diet-MSG when compared with control. Treatment with Annona muricataextractsbrought about a significant (P<0.05) deacrease in the concentrations of CHOL, TRIG, LDL and an increase in the concentration of HDL in a dose- dependent manner. Treatment with the extracts also brought about a significant increase (P<0.05) in reduced glutathione(GSH), superoxide dismutase (SOD), nitric oxide (NO) and catalase and a significant decrease in lipid peroxidation when compared with the induced group. Equally, treatment with Annona muricataextracts increased the expression of adiponectin, decreased the expression of (adipose tissue and liver) ACC, HMG COA reductase, FABPs genes. In conclusion, this study shows that methanol extracts of Annona muricata fruit and leaf have anti hyperlipidemia effect and reduced obesity-mediated oxidative stress in monosodium glutamate and high fat diet treated rats.