Myrtenal alleviates hyperglycaemia, hyperlipidaemia and improves pancreatic insulin level in STZ-induced diabetic rats.

CONTEXT: Myrtenal is monoterpene a constituent of essential oils found mainly in herbs such as mint, pepper, cumin, etc. It exerts admirable pharmacological activities against many diseases including diabetes. Hyperlipidaemia is a secondary complication of diabetes and also a major risk factor for cardiovascular diseases.

OBJECTIVE: The present study investigated the possible antihyperlipidaemic efficacy of myrtenal on plasma glucose, pancreatic insulin, plasma and tissue lipid levels in streptozotocin (STZ) induced diabetic rats.

MATERIALS AND METHODS: Diabetes was induced in male Wistar rats by a single intraperitoneal injection of STZ (40 mg/kg b.w.). Myrtenal (80 mg/kg) was administered orally to diabetic rats for a period of 28 d. Plasma glucose, pancreatic insulin, TC, TGs, FFAs, PLs, LDL-C, HDL-C, VLDL, atherogenic index, (HMG-CoA) reductase, LPL, LCAT and liver histology were analyzed.

RESULTS: Diabetic rats showed significantly (p < 0.05) increased plasma glucose (273.18 mg/dL), total cholesterol (142 mg/dL), triglycerides (126 mg/dL), free fatty acids (118 mg/dL), phospholipids (153 mg/dL), low-density lipoprotein (88.07 mg/dL), very low-density lipoprotein (25.2 mg/dL), atherogenic index, whereas a decrease in the levels of pancreatic insulin (97.48 ng/mg) and high-density lipoprotein (29.12 mg/dL). In addition, the activity of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase (0.94 HMG-CoA ratio/(mevalonate) increased significantly in contrast to the activities of lipoprotein lipase (4.87 μmoles of glycerol liberated/h/L) and lecithin cholesterol acyltransferase (54.61 μmoles of cholesterol esterified/h/L) in diabetic rats. Treatment with myrtenal significantly (p < 0.05) improved the levels of plasma glucose, pancreatic insulin and lipid profiles. Moreover, the histopathological analysis of liver was also in agreement with the biochemical findings.

DISCUSSION AND CONCLUSIONS: The present study indicates that myrtenal possess antihyperglycaemic and antihyperlipidemic properties, and could potentially be a useful phytochemical in treating diabetes.