ABSTRACT
The anti-obesity properties of ethanolic extract of Sphenostylis stenocarpa on high fat diet-induced obese rats was investigated for a period of 28 days. A total of 72 adult albino rats were used for the study. The rats were divided into 6 groups, (A- F) comprising of 12 rats each and the groups were further replicated three times, with 4 rats each. Obesity was induced in rats of groups B to F, by feeding the rats daily with high fat diet comprising of 45% fat, 20% protein and 26% carbohydrate, for 5 weeks. Only rats with an abdominal circumference (AC) of 20 cm, thoracic circumference (TC) of 17 cm and body mass index (BMI) of 0.82 kg/m2 and above respectively were considered obese and used for the study. The extract which was obtained by standard methods was screened phytochemically. The rats in the normal control (group A) and negative control (group B) were given water and food only, while the rats in the positive control (group C) received 60 mg/kg of orlistat by oral inturbation. Furthermore, rats in groups D, E and F were administered graded doses 200 mg/kg, 400 mg/kg and 600 mg/kg of the extract, respectively. The anthropometrical parameters of the rats were determined before the commencement of treatment (week 0) and subsequently on a 7 days interval. Similarly, blood samples were obtained from the orbital sinus of each rat for the various biochemical and hormonal analyses before commencement of treatment (week 0) and subsequently on a weekly basis. The blood samples were used to ascertain the serum levels of total cholesterol level (CHO), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), serum triglyceride (TG), total antioxidant substance (TAS), aspartate aminotransferase (AST), alanine aminotransferase (ALT), fasting blood glucose (FBG), leptine and cortisol, respectively. There was no overall dose and time dependent significant difference observed in the mean weekly anthropometrical parameters of the treatment groups when compared with negative and positive control groups. However, it was observed that the thoracic circumference of the rats administered 200mg/kg of the extract was significantly reduced (P < 0.05) in the 4th week. Similarly, the abdominal circumference and the body weights of the rats that received 400mg/kg were significantly reduced (P < 0.05) in the 4th week respectively. It was equally noticed that the body mass index of the rats in the 400mg/kg treatment group significantly reduced in the 4th week. There was an overall significant decrease (P < 0.05) observed in the serum levels of CHO, LDL-C, TAG, ALT and FBGL of the rats in the treatment groups when compared with the positive and negative controls. Secondly, whereas no significant difference (P > 0.05) was observed in the serum levels of V-LDL and AST, a significant increase (P < 0.05) occurred in the HDL-C and total antioxidant levels. Whereas no overall significant difference (P > 0.05) was observed in the serum leptin and cortisol levels of the treated rats when compared with the negative control group, a significant increase (P < 0.05) was noticed in comparison with the positive control group. Conclusively, the ethanolic seed extract of Sphenostylis stenocarpaseems to possess some anti obesity potentiality which effect may become very evident with longer duration of treatment. Secondly, it possesses hypolipidaemic, hyypoglycemic and hepatoprotective effects.
CHAPTER ONE
INTRODUCTION AND LITERATURE REVIEW
- Introduction
The word obesity comes from the Latin obesitas, which means stout, fat, or plump. It refers to an abnormal fat accumulation to the extent that it may have adverse effects on the health and well-being of an individual (Greenway and Smith, 2000). Physiologically, obesity is a disarray of energy balance primarily considered as a disorder of lipid metabolism (Karalis et al., 2009). This occurs when energy uptake surpasses energy expenditure in an individual such that the stores of energy in body fat are enlarged, particularly the adipose tissues (Norris et al., 2005). Obesity involves both or either, an increase in the number of adipocytes (hyperplasia) and their size (hypertrophy) (Jequier, 2002).
Evaluating overweight and obesity in individuals or groups is normally based on the measurement of anthropometric indicators, serum biochemistry profile and hormonal profile (Ahima and Lazar, 2013). Such anthropometric indicators ranges from abdominal circumference, to thoracic circumference, body weight, weight gain and body mass index (BMI; kg/m2). Obesity was positively associated with unfavorable values of low density Lipoprotein cholesterol, high density lipoprotein cholesterol, and serum triglycerides in human (Ahima and Lazar, 2013).
Obesity is itself a disease state, and is also a risk factor for many chronic disease conditions. It reduces life expectancy, increases the risk of coronary heart disease, stroke and gout (Slanc et al., 2009). It strongly predicts increased risk of type 2 diabetes, insulin resistance, hypertension, dyslipidaemia, gall bladder disease and non-alcoholic fatty liver disease (de Ferranti and Mozaffarian, 2008). It is associated with obstructive sleep apnoea and reduced quality of life. It has been linked with increased risk of some surgical and post-surgical complications (NHMRC, 2003). It is considered as a major leading cause of unnecessary deaths and in spite of the number of studies to prevent or treat obesity, its prevalence continues to increase with an estimated 400 million obese and 1.6 billion overweight adults around the world (WHO, 2005). It is equally estimated that, by the year 2030, about 58% of the world population will be obese i.e. (Body mass index, BMI >30) (Peltonen et al., 2003).
