Antihyperlipidemic effect of Eugenia jambolana seed kernel on streptozotocin-induced diabetes in rats
Introduction
Diabetes mellitus, an endocrine disorder, is a major source of morbidity in developed countries. The metabolism of all fuels including carbohydrates, fats and proteins are altered in diabetes and patients with diabetes have lipid disorders and an increased risk of coronary heart disease, peripheral vascular disease and cerebrovascular disease (Brown, 1994, Stamler et al., 1993). Diabetes is associated with profound alterations in the plasma lipid and lipoprotein profile and with an increased risk of premature atherosclerosis, coronary insufficiency and myocardial infarction (Betteridge, 1997).
Accumulation of lipids in diabetes is mediated through a variety of derangements in metabolic and regulatory processes, especially insulin deficiency, thereby rendering the diabetic patient more prone to hypercholesterolemia and hypertriglyceridemia (Jaiprakash et al., 1993). One of the major pathogenesis of lipid metabolism disturbances in diabetes is the increased mobilization of fatty acids from adipose tissue and secondary elevation of free fatty acid level in the blood (Singh et al., 1987). Excessive lipolysis has been found to occur during diabetes. One of the consequences of excessive mobilization of fatty acid is the production of ketone bodies in the liver. The excessive lipolysis in diabetic adipose tissue leads to increase free fatty acids in circulation. They enter the liver and are esterified to form triglycerides (Hem, 1977). Fatty acids are required for both the structure and function of every cell in the body and they form an important component of cell membranes. Several authors have reported that, the fatty acid compositions of various tissues are altered in both experimental and human diabetes (Faas et al., 1988, Tilvis and Miettinen, 1985).
Many indigenous Indian medicinal plants have been found to be useful to successfully manage diabetes. Despite the introduction of hypoglycemic agents from natural and synthetic sources, diabetes and its secondary complications continue to be a major medical problem in the world population. Eugenia jambolana Lam (Fam: Myrtaceae) commonly called as Jamun, Black plum or Indian Black berry. Eugenia jambolana seeds have hypoglycemic, anti-inflammatory, neuropsycho-pharmacological, anti-bacterial, anti-HIV and anti-diarrheal effects (De Lima et al., 1998). Bhatia and Bajaj, 1975) have reported that the Eugenia jambolana seed contains several biologically active constituents such as flavonoids, gallic acid, ellagic acid, glycosides, triteripenoids and saponins. Recently, we have reported the anti-diabetic and anti-oxidant property of Eugenia jambolana seed kernels on streptozotocin-induced diabetic rats (Ravi et al., 2003, Ravi et al., 2004a, Ravi et al., 2004b, Ravi et al., 2004c). The present study was aimed to investigate the effect of Eugenia jambolana seed kernel on lipid constituents and fatty acid composition in plasma and tissues of streptozotocin-induced diabetic rats. The efficacy was compared with a standard hypoglycemic drug, glibenclamide.
Section snippets
Chemicals
Streptozotocin was procured from Sigma Chemical Co., St. Louis, MO, USA. All other chemicals used were of analytical grade.
Plant material
Fresh, mature Eugenia jambolana fruits were collected from a tree in Kolli Hills, Tamil Nadu, India. The plant was identified at the Herbarium of Botany, CAS in Botany, University of Madras. An exemplar voucher specimen (no. 1283) was deposited in the department herbarium.
Preparation of plant extract
The fruits of jambolana were washed well and pulp was removed. The seeds were washed with distilled
Results
Table 1 depicts the levels of serum total cholesterol, triglycerides, free fatty acids and phospholipids in control and experimental groups of rats. A significant (p < 0.05) increase in the levels of plasma lipids was observed in diabetic rats (Group II), which were restored, to near normal by the treatment of EJs-kernel (Group III) or glibenclamide (Group IV).
Fig. 1 shows the levels of serum HDL, LDL and VLDL-cholesterol in control and experimental groups of rats. The levels of LDL and
Discussion
In the present study, a marked increase in the lipid content of serum, liver and kidney were found in STZ-induced diabetic rats. The increase in the serum lipids on the diabetic subject is mainly due to the increased mobilization of free fatty acids from peripheral deposits, since insulin inhibits the hormone sensitive lipase (Al-Shamaony et al., 1994). On the other hand, glucagon, catecholamines and other hormones enhance lipolysis. The marked hyperlipemia that characterizes the diabetic state
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