Cinnamaldehyde Mitigates Carbon Tetrachloride-induced Acute Liver Injury in Rats Through Inhibition of Toll-like Receptor 4 Signaling Pathway

Cinnamaldehyde Mitigates Atherosclerosis Induced by High-Fat Diet via Modulation of Hyperlipidemia, Oxidative Stress, and Inflammation

Atherosclerosis is a disease in which plaque builds up inside arteries. Cinnamaldehyde (Ci) has many biological properties that include anti-inflammatory and antioxidant activities. Thus, this study was designed to explore the protective effect of Ci against atherosclerosis induced by a high-fat diet (HFD) in Wistar rats. Atherosclerosis was induced by an oral administration of an HFD for 10 weeks. Atherosclerosis-induced rats were supplemented with Ci at a dose of 20 mg/kg bw dissolved in 0.5% dimethyl sulfoxide (DMSO), daily by oral gavage for the same period. Rats were divided into three groups of 10 rats each fed with (a) ND, (b) HFD, and (c) HFD+Ci, daily for 10 weeks. Treatment of rats with Ci significantly reduced the elevated levels of serum total cholesterol (T.Ch), triglycerides (TG), low-density lipoprotein-cholesterol (LDL-Ch), very low-density lipoprotein-cholesterol (VLDL-Ch), and free fatty acids (FFAs) and significantly increased the lowered levels of high-density lipoprotein-cholesterol (HDL-Ch) level. Ci ameliorated the increased cardiovascular risk indices 1 and 2 and the decreased antiatherogenic index. Moreover, Ci reduced the elevated serum creatine kinase (CK), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) activities. Ci also improved the heart antioxidant activities by decreasing malondialdehyde (MDA) and increasing glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and glutathione peroxidase (Gpx) activities. Furthermore, the supplementation with Ci downregulated the mRNA expression levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-17 (IL-17), and tumor necrosis factor-α (TNF-α). Thus, Ci successfully elicited a therapeutic impact against atherosclerosis induced by HFD via its hypolipidemic, antioxidant, and anti-inflammatory actions.

Cinnamaldehyde and eugenol protect against LPS-stimulated oxidative stress and inflammation in Raw 264.7 cells

Macrophages are leukocytes that play a strategic role in immune response and can be associated with various diseases due to their effects on the inflammation process and oxidative events. The current study was evaluated the anti-inflammatory and antioxidant properties of cinnamaldehyde and eugenol, which are phyto-compounds with numerous bioactive properties, on lipopolysaccharide (LPS)-induced macrophage cells. For this purpose, Raw 264.7 cells were incubated with cinnamaldehyde or eugenol (15, 25, and 50 μM) then stimulated with LPS. After 24 hr, tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 levels (as inflammatory mediators), and malondialdehyde (MDA) and nitric oxide (NOx) levels as well as superoxide dismutase (SOD) and catalase (CAT) activities (as oxidative status markers) were determined in cell cultures. Cinnamaldehyde and eugenol pre-treatments decreased TNF-α, IL-1β, and IL-6 levels as compared to LPS group at all concentrations. Furthermore, these pre-treatments increased SOD activity while decreased MDA and NOx levels as well as CAT activity at different concentrations. Our results demonstrated that these phyto-compounds have potential for the treatment of various diseases as protective agents against chronic inflammation and oxidative stress. PRACTICAL APPLICATIONS: Chronic inflammation and oxidative stress are complications that play a detrimental role in the pathophysiology of many diseases. Alternative treatment methods have been investigated to prevent them. Cinnamaldehyde and eugenol are phyto-compounds with high bioactivity that can be obtained from foods and spices. In this study, the protective effects of cinnamaldehyde and eugenol on lipopolysaccharide-induced oxidative stress and inflammation in macrophage cells were investigated. According to the obtained results, cinnamaldehyde and eugenol pre-treatments decreased inflammation and also reduced oxidative stress. Cinnamaldehyde and eugenol may be a better natural alternative protective agent for the chronic inflammation- and oxidative stress-related diseases.

Cinnamaldehyde and eugenol attenuates collagen induced arthritis via reduction of free radicals and pro-inflammatory cytokines

BACKGROUND

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease which leads to bone and cartilage erosion. Oxidative stress and pro-inflammatory cytokines plays crucial role in the pathophysiology of RA. Cinnamaldehyde and eugenol have a long history of medical use in various inflammatory disorders.

PURPOSE

The drugs available for the treatment of RA are associated with various side effects. The present study was conducted to evaluate the anti-arthritic effects of cinnamaldehyde and eugenol in rat model of arthritis.

METHODS

Type II collagen was intradermally injected to rats for the induction of arthritis. Cinnamaldehyde (10 and 20 mg/kg/day) and eugenol (10 and 20 mg/kg/day) were given orally for 15 days, starting from day 21 to 35. Dexamethasone treated rats served as positive control. Histological, radiological and scanning electron microscopic analysis were done to monitor the effect of compounds on collagen induced arthritis (CIA). Reactive oxygen species (ROS) formation, nitric oxide and antioxidant status were also determined. The markers of biomolecular oxidation (protein, lipid and DNA) and activities of enzymatic antioxidants (superoxide dismutase, glutathione peroxidase, catalase and glutathione reductase) were also evaluated in the joint homogenate and plasma of rats. For detecting inflammation, levels of TNF-α, IL-6 and IL-10 were monitored by ELISA.

RESULTS

Our results showed anti-oxidant and anti-inflammatory effects of cinnamaldehyde and eugenol in arthritic rats. Scanning electron microscopy, histopathological and radiological findings also confirmed the anti-arthritic effects of cinnamaldehyde and eugenol. Both the compounds were effective in bringing significant decrease in the levels of ROS, nitric oxide, markers of biomolecular oxidation and increase in enzymatic and non-enzymatic antioxidants. The levels of TNF-α, IL-6 and IL-10 were also ameliorated by cinnamaldehyde and eugenol treatment. Between the two phytochemicals used, eugenol was found to be more effective than cinnamaldehyde in reducing the severity of arthritis.

CONCLUSION

Cinnamaldehyde and eugenol were effective in ameliorating oxidative stress and inflammation in arthritic rats. These findings indicate that cinnamaldehdye and eugenol have a great potential to be used as an adjunct in the management of RA.

Glycyrrhizic acid and silymarin alleviate the neurotoxic effects of aluminum in rats challenged with fructose-induced insulin resistance: possible role of toll-like receptor 4 pathway

Aluminum is implicated in the etiology of different neurodegenerative diseases, diabetes and cancer. The current study was conducted to evaluate the protective effects of glycyrrhizic acid (GAM) and silymarin (SLY) on AlCl₃-induced neurotoxicity in insulin resistant rats. Insulin resistance (IR) was induced by fructose (10%) in drinking water for 18 weeks. Rats received AlCl₃ (34 mg/kg/day) with or without fructose, GAM (40 mg/kg/day), or SLY (100 mg/kg/day). The administration of GAM or SLY suppressed AlCl₃-induced memory deficit, oxidative stress, and neuroinflammation in brain tissue of IR rats. Both agents inhibited AlCl₃-induced activation of TLR4 signaling pathway including the downstream activation of NF-κB. The results show that IR can partly exacerbate AlCl₃-induced neurotoxicity, particularly memory deficit and neuroinflammation. In addition, GAM and SLY showed promising neuroprotective effect against AlCl₃-induced brain damage in IR rats. The neuroprotection induced by these natural products might be mediated through their antioxidant and anti-inflammatory effects. The latter effect seems to be mediated via inhibition of TLR4 signaling pathway providing new insights on the mechanisms implicated in AlCl₃-induced neurotoxicity and the neuroprotection afforded by GAM and SLY.