|ISSN No. 1606-7754 Vol.13 No.1 April 2005|
Anti-hyperglycaemic and anti-dyslipidaemic effect of dietary supplement of white Ocimum Sanctum Linnean before and after STZ-induced diabetes mellitus
Thamolwan Suanarunsawat1* and Thanapat Songsak2
Physiology Unit, Department of Medical Sciences, Faculty of Sciences, Rangsit University, Paholyotin Rd.,Thailand, 120001 Department of Pharmacognosy, Faculty of Pharmacy, Rangsit University, Paholyotin Rd.,Thailand, 120002
This study was conducted to elucidate whether dietary treatment of white Ocimum sanctum Linnean. (OS) either before or after streptozotocin (STZ) - induced diabetes has anti-hyperglycemic and anti-dyslipidaemic action. Two series of experiments were performed. The first involved three groups of rats; one group was fed normal diet for 6 weeks, a second diabetic group received normal diet and a third diabetic group received 2 % dietary OS from 3 weeks after induction of diabetes for a period of 3 weeks. The second involved three groups of rats: one group was fed normal diet, a second group received or did not receive 2 % dietary white OS before induction of diabetes. Fasting blood glucose was determined before and after induction of diabetes. At the end of the study, arterial blood was collected to evaluate serum triglyceride, total cholesterol, HDL-cholesterol, LDL-cholesterol, serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT) and creatinine. The results show that blood glucose was not significantly altered after 3 weeks of dietary supplement of white OS in diabetic rats. In contrast, elevated blood glucose after 3 weeks of diabetes was alleviated in diabetic rats pretreated with white OS. STZ-induced diabetes significantly raised serum triglyceride, total cholesterol, LDL-cholesterol, AST, ALT and creatinine. White OS supplementation, either before or after induction of diabetes, normalized lipid profile and creatinine and partially reduced an elevated serum AST and ALT. It can be concluded that STZ-induced hyperglycaemia can be ameliorated by pretreatment with white OS. Dietary supplement with OS either before or after diabetic induction reverses dyslipidaemia and renal glomerular filtration function, and partially protects liver function.
Key words: diabetes mellitus, serum lipid, Ocimum sanctum Linnean.
Diabetes mellitus (DM) is a serious metabolic disease which has several complications including diabetic nephropathy, diabetic neuropathy, coronary heart disease and hypertension.1 It has been estimated that by the year 2010, the prevalence of DM worldwide will reach approximately 240 million.2 Patients with DM are more likely to develop and die from microvascular and macrovascular complications than the non-diabetic population.3 There is usually an association between coronary heart disease or atherosclerosis and dyslipidaemia.4,5 Dyslipidaemia is a frequent complication of DM and is characterized by low levels of HDL-cholesterol and high levels of LDL-cholesterol and triglyceride. Several groups of hypoglycaemic drugs are currently available to treat DM. However, their toxic side effects and sometimes diminution in response after prolonged use are problematic. Management of DM to avoid these problems is still a major challenge. There is an ongoing search for natural products with anti-hyperglycaemic and anti-dyslipidaemic activities with minimal side effects. There are several kinds of medicinal plants in Thailand which have been reported to exert anti-hyperglycaemic and/or anti-dyslipidaemic actions.6 Among them, Ocimum sanctum Linnean. (OS) is very promising since it is routinely used as a vegetable and also for the treatment of DM by local people in various countries including India and Thailand. Several studies have demonstrated that OS possesses anti-hyperglycaemic and/or anti-dyslipidaemic effect in normal and DM animals.7-10 Preliminary studies in our laboratory have shown that white OS exerts hypoglycemic action in normal rats whereas red OS was without this effect. We have investigated whether supplementation of diet with white OS can retard dyslipidaemia and hyperglycaemia in diabetes.
Materials and methods
Male Wistar rats weighing between 180-220 g from Animal Center, Salaya Campus, Mahidol University, were used in the study. Rats were housed in a 12-hr light-dark cycle at 25 2 C and fed normal rat food and tap water ad libitum. All animals were cared for in accordance with the principles and guidelines of the Institutional Animal Ethics Committee of Rangsit University, which is under The National Council of Thailand for Animal Care. Induction of diabetes was carried out by intraperitoneal injection of STZ (Sigma, St Louis, MO, USA) dissolved in citrate buffer pH 4.5 at a dose of 70 mg/kg bodyweight. Two days after STZ injection blood glucose was measured and only those rats with fasting blood glucose >170 mg/dl were included in the study
Preparation of white Ocimum sanctum Linnean
Fresh leaves of white OS obtained from The Ministry of Public Health, Thailand, were washed in tap water and then left to dry at room temperature for 2-3 days. The dried leaves were then ground to fine powder in a mixer. The dried leaf powder was then added to the diet to makeup 2 % of the diet.