Effects of Curcurma comosa Roxb. on Platelet Aggregation and Atherosclerotic Plaque Development in Hypercholesterolemic Rabbits

Curcuma comosa Roxb. (C. comosa), an indigenous medicinal plant containing phytoestrogens, has been reported to have hypocholesterolemic and anti-inflammatory effects. Hypercholesterolemia and inflammation play crucial roles in the development of atherosclerosis. In the present study we investigated whether the hexane extract of C. comosa inhibits atherosclerotic plaque formation and platelet aggregation in hypercholesterolemic rabbits. Rabbits were fed 0.5% cholesterol (N = 6), 0.5% cholesterol plus 5 mg day(-1) of simvastatin (N = 6), 0.5% cholesterol plus 100 mg kg(-1) b.wt./day of C. Comosa extract (N = 6) or normal rabbit chow (N = 6) for 12 weeks. Blood samples for cholesterol determination were collected in monthly intervals. At the end of the study period, platelet aggregation ex vivo, endothelium-dependent and -independent vascular function of isolated aortic rings ex vivo and aortic plaques were assessed. Cholesterol feeding to the rabbits for 12 weeks significantly increased plasma lipid profiles, platelet aggregation and impaired endothelium-dependent relaxations to ACh and ADP. Supplement with simvastatin or hexane extract of C. comosa attenuated platelet aggregation, plasma lipid profiles and partly restored endothelium-mediated vascular responses. Both simvastatin and hexane extract of C. comosa also improved aortic intimal thickening by about 76 and 74%, respectively. The results indicate that hexane extract of C. comosa possesses the beneficial effects in hypercholesterolemia in similar manner to simvastatin. The therapeutic potential for the prevention or regression of atherosclerosis should be further investigated.