Abstract
The present study aimed to investigate the protective role of cinnamon extract against inflammatory and oxidative injuries in gamma irradiated rats. Rats were subjected to fractionated doses of gamma radiation. Cinnamon extract were daily administrated before starting irradiation and continued after radiation exposure. The results obtained revealed that the administration of cinnamon extract to irradiated rats significantly ameliorated the changes induced in liver antioxidant system; catalase, superoxide dismutase and glutathione peroxidase activities as well as reduced glutathione concentration. The liver's lipid peroxidation and protein oxidation indices were significantly decreased when compared with their equivalent values in irradiated rats. Furthermore, the changes induces in xanthine oxidoreductase system were significantly diminished. In addition, the changes in liver nitric oxide contents, serum tumor necrosis factor alpha and C-reactive protein levels were markedly improved. In conclusion, the administration of cinnamon extract might provide substantial protection against radiation-induced oxidative and inflammatory damages.
Exposure to ionizing radiation (IR) increases the production of reactive oxygen species (ROS) through radiolysis of water molecules (1) and shifting xantine oxidoreductase system into the radicals generating the form: xanthine oxidase (XO) (2).
The resulting overproduction of ROS induces (a) protein oxidation and the subsequent production of protein carbonyl, (b) lipid peroxidation and the subsequent thiobarbituric acid reactive substances (TBARS) and (c) activation of nuclear factor kappa B (NF-kB), a transcription factor, which by itself activates nitric oxide production by activation expression of inducible nitric oxidesynthase (iNOS) gene. Furthermore, it stimulates overproduction of tumor necrosis factor-alpha (TNF-α), a pro-inflammatory cytokine that enhances NF-kB activation and induces the acute phase protein (CRP) production eventually resulting in inflammatory process, which causes more production of ROS.
Cinnamon antioxidant ingredients scavenge and stop the progress of ROS generation through direct scavenging of the initiating radicals, reduce shifting of XOR into the radical generating (XO) form and enhance the capability of cellular antioxidants to cope with the free radicals generated by radiation and all these resulting in inhibition of lipid peroxidation and protein oxidation processes and decrease in oxidative stress markers: TBARS and protein carbonyl levels. Moreover, scavenging of ROS resulted in NF-kB deactivation and subsequent inhibition of pro-inflammatory cytokine and CRP release as well as decreased iNOS gene expression and the subsequent NO production. Thus, the amelioration of ionizing radiation-induced inflammation by cinnamon extract involves the suppression of a variety of pro-inflammatory mediators by preventing ROS and TNF-α mediated NF-kB activation.
[Display omitted]
► Ionizing radiation induced overproduction of ROS and decreased cellular antioxidant. ► ROS increase the production of inflammatory cytokines (TNF-α). ► Cinnamon extract suppress a variety of pro-inflammatory mediators. ► Prevent ROS and TNF-α mediated NF-κB activation. ► Ameliorate ionizing radiation-induced inflammation and cellular damages.