D Adeyemi, O Komolafe, S Adewole, E Obuotor
diabetes mellitus, hyperglycemia, serum lipid profiles, streptozotocin
D Adeyemi, O Komolafe, S Adewole, E Obuotor. Anti Hyperlipidemic Activities Of Annona Muricata (Linn). The Internet Journal of Alternative Medicine. 2008 Volume 7 Number 1.
This study was designed to determine the effects of methanolic extracts of
Diabetes mellitus (DM) is associated with an increased risk of thrombotic, atherosclerotic and cardiovascular disease. Hyperlipidemia is metabolic complication of both clinical and experimental diabetes1. Low-density lipoprotein in diabetic patients leads to abnormal metabolism and is associated with increase in very low-density lipoprotein (VLDL) secretion and impaired VLDL catabolism. Ultimately this leads to atherosclerotic plaque 2. A number of known factors for coronary artery disease such as hypertension, obesity and dyslipidemia are more common in diabetics than in the general population. The World Health Organization (WHO) predicts that the number of cases worldwide for diabetes, now as of 171 million, will touch 366 million or more by the year 20303. Patients with DM are more likely to develop microvascular and macrovascular complications than the non diabetic population 4. Dyslipidemia is a frequent complication of DM and is characterized by low levels of high density lipoprotein-cholesterol (HDL-C) and high levels of low density lipoprotein-cholesterol (LDLC) and triglyceride (TG). Several groups of hypoglycemic drugs are currently available to treat DM.
Treatment of hyperlipidemia in diabetes involves improving glycemic control, exercise and the use of lipid lowering diets, drugs and hypoglycemic agents 56. Mendez and Balderas 7 showed that non-glucidic nutrient such as L-arginine administration tended to normalize the glycemia, hyperlipidemia, and lipid peroxidation, which indicates non-glucidic nutrients exerted an inhibitory effect on lipid peroxidation and also improve the lipid profile, that may be relevant in preventing diabetic complications. The objective of this study was to investigate the anti hyperlipidemic properties of extracts of Annona muricata leaves
Materials And Methods
Preparation of extract
Care and management of animals
Thirty healthy adult Wistar rats (Rattus norvegicus) of both sexes, weighing between 150g and 250g were used for the experiment. The rats were bred in the animal holding of department of Anatomy and Cell Biology Obafemi Awolowo University Ile Ife, were maintained on standard rat pellets (Ladokun feeds, Ibadan, Nigeria), and were given water
Acute toxicity test
Forty adult male Wistar rats (150 – 200g) were randomly assigned into six groups (T1, T2, T3, T4, T5 and T6) of eight animals in each group. T1 was treated with distilled water and is considered as control. The other five groups were treated with methanolic extract of
Administration of streptozotocin and
Diabetes mellitus was experimentally induced in groups B and C by a single intraperitoneal injection of 80mg/kg body weight. streptozotocin (Sigma, St. Louis, USA) dissolved in 0.1M sodium citrate buffer pH 6.3. The control (group A animals) were injected intraperitoneally with equivalent volume of the citrate buffer. The rats were fasted overnight before STZ administration. The serum lipid profiles were monitored weekly in the animals for the next four weeks. After four weeks of experimental-induction of diabetes, group C rats were given daily intraperitoneal injection of 100mg/kg of extracts of
The serum levels of triglyceride (TGL), total cholesterol (TC) and high-density lipoprotein-cholesterol (HDLC) were determined spectrophotometrically, using enzymatic colorimetric assay kits (Randox, Northern Ireland) while low-density lipoprotein cholesterol (LDLC) and very low-density lipoprotein cholesterol (VLDLC) were calculated. Animals were fasted for 12-16 hours before blood samples were obtained. About two milliliters of blood was collected from the tail vein of each rat into an ice-cold centrifuge tubes. The blood samples were centrifuged in a Denley BS400 centrifuge (England) at 5000 R.P.M for 5-minutes. The supernatant (serum) collected was assayed for the serum levels of TGL, TC and HDL-C using the Randox Biochemical kits while LDL-C and VLDL-C were calculated.
Assay for triglycerides
The serum level of TGL was determined by the method of Treitz 17. 1000 μl of the reagent was added to 10μl each of the sample and standard. This was incubated for 10 minutes at 20-25°C and the absorbance of the sample (A sample) and standard (A standard) was measured against the reagent blank within 30 minutes.
Assay for Total Cholesterol
The serum level of TC was determined after enzymatic hydrolysis and oxidation of the sample as described by Richmond 18 and Roeschlau
Assay for HDLC
Low-density lipoproteins (LDL and VLDL) and chylomicron fractions in the sample were precipitated quantitatively by the addition of phosphotungstic acid in the presence of magnesium ions. The mixture was allowed to stand for 10 minutes at room temperature centrifuged for 10 minutes at 4000rpm. The supernatant represented the HDLC fraction. The cholesterol concentration in the HDL fraction, which remains in the supernatant, was determined.
Low density lipoprotein - cholesterol
The concentration of LDL cholesterol was calculated mmol/L using Friedewald’s equation 20 as stated below.
Very low density lipoprotein - cholesterol
The concentration of VLDL cholesterol was calculated mmol/L using Friedewald’s equation 20 as stated below.
Antiatherogenic Index (AAI)
The antiatherogenic index was calculated according to the method of Guido and Joseph21. AAI was calculated from total cholesterol and HDL cholesterol using the formula below;
The values were expressed as a percentage
The data were analysed using descriptive and inferential statistics. All values are presented as mean ± standard error of mean (SEM) for ten rats in each of the three group of rats. The significance of difference in the means of all parameters reported for the three groups of animals was determined using paired sample student t – test and a p – value of < 0.05 (two tailed) was considered as significant.
Effects of on the serum lipid profiles
Tables 1 and 2 illustrate the effects of
Values are given as mean ± SEM for ten rats in each group.
a, b within column signifies that means with different letters differs significantly at P < 0.05 (two tailed T-test) while means with the same letters does not differ significantly at P <0.05 (two tailed T-test)
Values are given as mean ± SEM for ten rats in each group.
a, b within column signifies that means with different letters differs significantly at P < 0.05 (two tailed T-test) while means with the same letters does not differ significantly at P <0.05 (two tailed T-test
Diabetes mellitus is associated with profound alteration in the serum lipid and lipoprotein profile with an increased risk in coronary heart disease 5. Hyperlipidemia is a recognized complication of Diabetes mellitus characterized by elevated levels of cholesterol, triglycerides and phospholipids; and changes in lipoprotein composition 22. The result of this present study clearly shows that
Increased triglycerides and reduced HDL-C levels are the key characteristics of dyslipidemia in type 2 diabetes 23. Hypertriglyceridemia in type 2 diabetes can result from an increased hepatic very low-density lipoprotein (VLDL), overproduction and impaired catabolism of triglyceride-rich particles. The function of lipoprotein lipase, the key enzyme in removal and degradation of triglycerides is attenuated by both insulin deprivation and insulin resistance.
The abnormal high concentration of serum lipids in diabetes is mainly due to the increase in the mobilization of free fatty acids (FFA) from the peripheral depots, since insulin inhibits the hormone sensitive lipase 24. Serum – FFA concentration are a result of the balance between the release from lipolysis, neosythesis and disposal and represent the major determinant of insulin effect on free fatty and oxidation and non-oxidative metabolism 25.
Hypercholesterolemia and hypertriglyceridemia have been reported to occur in diabetic rats 26 and significant increase in total cholesterol and triglycerides observed in the present experiment was in accordance to these studies. Furthermore, increase in circulatory VLDL and their associated triglycerides are largely due to defective clearance of these particles from circulation 22. The increase and fall in the individual lipoprotein levels is a reflection of the serum total cholesterol levels i.e. the levels of HDL-C, LDL-C and VLDL-C increase or decrease with the levels of total serum cholesterol, and it is their ratio that determines the pathophysiology of lipoprotein metabolism. As there is a close relationship between elevated serum total cholesterol level and occurrence of atherosclerosis, the ability of the
Due to the fact that
The authors thank Dr. O.O. Komolafe for his assistance.
Adeyemi David Olawale Department of Anatomy and Cell Biology, Obafemi Awolowo University, Ile Ife, Nigeria E-mail: firstname.lastname@example.org Telephone +2348034259540, +2348050362745