Effects of Cinnamomum cassia extract on oxidative stress, immunreactivity of iNOS and impaired thoracic aortic reactivity induced by type II diabetes in rats

Type II diabetes is known to cause neuropathy, nephropathy and retinopathy. However, cardiovascular disorders associated with diabetes have been ignored. In traditional medicine, cinnamon (Cinnamomum cassia) bark has been used for its abilities to relieve fever, inflammation and chronic bronchitis. In the present study, the effect of Cinnamomum cassia extract (CN) on the thoracic aorta in an experimental type II diabetes model was investigated. In rats administered with nicotinamide + streptozotocin, significant endothelial dysfunction and oxidative stress were characterised by increased inducible nitric oxide synthase (iNOS) and decreased insulin/proinsulin levels. This impairment was prevented by administering 1000 mg/kg metformin or 500-1000-1500 mg/kg CN. CN administration attenuated the inflammatory response by decreasing the levels of malondialdehyde (MDA), Nitric oxide (NO) and increasing Glutathione peroxidase (GPx), glutathione (GSH). In addition, CN administration was shown to cause down-regulating effects on iNOS in thoracic aorta. These findings reveal that CN could prevent chronic complications of experimentally induced type II diabetes by attenuating inflammation, oxidant/antioxidant imbalance, and normalised contraction and relaxion responses in the thoracic aorta.

From type 2 diabetes to antioxidant activity: a systematic review of the safety and efficacy of common and cassia cinnamon bark.

Common (Cinnamomum verum, C. zeylanicum) and cassia (C. aromaticum) cinnamon have a long history of use as spices and flavouring agents. A number of pharmacological and clinical effects have been observed with their use. The objective of this study was to systematically review the scientific literature for preclinical and clinical evidence of safety, efficacy, and pharmacological activity of common and cassia cinnamon. Using the principles of evidence-based practice, we searched 9 electronic databases and compiled data according to the grade of evidence found. One pharmacological study on antioxidant activity and 7 clinical studies on various medical conditions were reported in the scientific literature including type 2 diabetes (3), Helicobacter pylori infection (1), activation of olfactory cortex of the brain (1), oral candidiasis in HIV (1), and chronic salmonellosis (1). Two of 3 randomized clinical trials on type 2 diabetes provided strong scientific evidence that cassia cinnamon demonstrates a therapeutic effect in reducing fasting blood glucose by 10.3%-29%; the third clinical trial did not observe this effect. Cassia cinnamon, however, did not have an effect at lowering glycosylated hemoglobin (HbA1c). One randomized clinical trial reported that cassia cinnamon lowered total cholesterol, low-density lipoprotein cholesterol, and triglycerides; the other 2 trials, however, did not observe this effect. There was good scientific evidence that a species of cinnamon was not effective at eradicating H. pylori infection. Common cinnamon showed weak to very weak evidence of efficacy in treating oral candidiasis in HIV patients and chronic salmonellosis.