Protective Effect of Nigella sativa Seed Extract and its Bioactive Compound Thymoquinone on Streptozotocin-induced Diabetic Rats

Background: The lack of a substantial breakthrough in the treatment of diabetes, a global issue, has led to an ongoing quest for herbs that contain bioactive elements with hypoglycemic properties. Objective: To investigate the potential protective effect of Nigella sativa seeds ethanol extract and its active ingredient, thymoquinone, on streptozotocin-induced diabetic rats. Methods: To induce diabetes, the male Wistar rats were administered an intraperitoneal injection of STZ at a dosage of 90 mg/kg body weight in 0.9 percent normal saline after being fasted for 16 hours and made diabetic Group 1; 7 rats non-diabetic control (saline-treated), Group 2; 7 untreated diabetic rats, Group 3; 7 diabetic rats treated orally with N. sativa extract at a dose of 100 mg/kg body weight, Group 4; 7 diabetic rats treated orally with thymoquinone at a dose of 10 mg/kg body weight and Group 5; 7 diabetic rats treated orally with Metformin at a dose of 5 mg/kg body weight. After the treatment of 28 days, all groups were examined for body weight and biochemical alterations. Results: The results showed a significant decrease in blood glucose, urea, creatinine, uric acid, total protein, total cholesterol, low-density lipoprotein, and very low-density lipoprotein, while high-density lipoprotein was increased. Hepatic enzymes, alanine transaminase, aspartate aminotransferase, and alkaline phosphate were also normalized and significantly increased body weight. Conclusion: These preliminary findings demonstrate that the ethanol extract of N. sativa seeds and its active ingredient, thymoquinone have a protective effect against streptozotocin-induced diabetic rats. The present study opens new vistas for the use of N. sativa and its bioactive compound, thymoquinone, regarding its clinical application as a new nontoxic antidiabetic agent for managing diabetes mellitus.