INHIBITORY EFFECT OF NIGELLA SATIVA (BLACK CUMIN) SEED EXTRACT ON THE GLYCATION OF PHOSPHATIDYLETHANOLAMINE

Abstract

Chronic hyperglycemia promotes the non-enzymatic glycation of the amino-containing phospholipids such as phosphatidylethanolamine (PE). This reaction yields the glycated-PE and PE-linked advanced glycation end products (AGE-PE) which are the contributing factors for diabetic complications. Thymoquinone (TQ), the main active compound in Nigella Sativa L. (Black cumin) seed, has been reported to have anti-protein glycation properties. However, the inhibitory effect of Nigella Sativa seed extract (NSE) on lipid glycation was still remained unknown. Therefore, this study aimed to investigate the inhibitory effect of ethanolic extract of NSE on the glycation of PE in commercial standard and erythrocyte model by using mass spectrometric technique. PE was incubated with glucose in the presence of NSE or TQ. The products of PE glycation including glycated-PE and AGE-PE (carboxymethyl-PE; CM-PE and carboxyethyl-PE; CE-PE) were analyzed. The results demonstrated that NSE inhibited products from PE glycation in a dose-dependent manner. The 40 mg/ml of NSE significantly reduced both glycated-PE and AGE-PE formation (p < 0.05). Moreover, NSE inhibited CM-PE to a greater extent than aminoguanidine (AG), a common anti-glycation agent, at the same concentration. TQ also showed the significant reduction in both glycated-PE and CM-PE. In erythrocyte experiment, however, no significant changes of glycated-PE and AGE-PE were observed in NSE treatment as compared to those in negative control. From the present study, it can be concluded that NSE might be other therapeutic option for the prevention of lipid glycation-induced pathogenesis of diabetic complications.