Potent Natural Antioxidant Carveol Attenuates MCAO-Stress Induced Oxidative, Neurodegeneration by Regulating the Nrf-2 Pathway

Abstract

Ischemic stroke is a severe neurological disorder with a high prevalence rate in developed countries. It is characterized by permanent or transient cerebral ischemia and it activates syndrome of pathological events such as membrane depolarization, glutamate excitotoxicity, and intracellular calcium buildup. Carveol is widely employed as anti-inflammatory and antioxidant in traditional Chinese medicine. In the present study, the neuroprotective effects of post-treated carveol were demonstrated against transient middle cerebral artery occlusion (MCAO) induced focal ischemic cerebral injury. Male Sprague Dawley (SD) rats were subjected to two different experimental protocols to determine the dose and effects of carveol, and to demonstrate the underlying role of the nuclear factor E2-related factor (Nrf2) pathway. Our results showed that MCAO induced marked neuronal injury in the ipsilateral cortex and striatum associated with higher inflammatory cytokines expression, along with apoptotic markers such as caspase-3 and the phosphorylated c-Jun N-terminal kinase (JNK). Furthermore, MCAO induced a marked increase in oxidative stress as evidenced by high lipid peroxidase (LPO) content accompanied by the depressed antioxidant system. Carveol significantly reversed the oxidative stress and downregulated inflammatory cascades by enhancing endogenous antioxidant mechanisms including the Nrf2 gene, which critically regulates the expression of several downstream antioxidants. Further, to determine the possible involvement of Nrf2 in carveol mediated neuroprotection, we antagonized Nrf2 by alltrans retinoic acid (ATRA), and such treatment abrogated the protective effects of carveol accompanied with exaggerated neuronal toxicity as demonstrated by higher infarction area. The target effects of carveol were further supported by molecular docking analysis of drug-protein interactions. Together, our findings suggest that carveol could activate endogenous master anti-oxidant Nrf2, which further regulates the expression of downstream antioxidants, eventually ameliorating MCAO-induced neuroinflammation and neurodegeneration.

Carveol a Naturally-Derived Potent and Emerging Nrf2 Activator Protects Against Acetaminophen-Induced Hepatotoxicity

“…The clinical syndrome of a higher dose of APAP has long been established, and the potent natural antioxidant carveol attenuates APAP-induced detrimental outcomes in hepatic tissue; thus, this study further attested to our previously published data. We previously demonstrated that carveol treatment attenuated ischemic stroke-induced neurodegeneration, by positively affecting the Nrf2 pathway, thereby leading to a reduced infarction area ( Malik et al, 2020 ). We demonstrated here that carveol reversed the oxidative and inflammatory cascades of APAP, possibly by triggering the Nrf2-dependent antioxidative mechanism, which is cross-linked to the pro-survival pathways ( Figure 10 ).…”

“…Moreover, role of the JNK pathway in inflammatory cascades and cellular death has been strongly established ( Ali A et al, 2020 ), and ROS and inflammatory cytokines can trigger JNK activation ( Ali A et al, 2020 ; Ali T et al, 2020 ; Ling et al, 2020 ). Furthermore, the p-JNK pathway has been implicated in various animal models and human diseases ( Shah et al, 2018 ; Li and Liu, 2019 ; Ali A et al, 2020 ; Ling et al, 2020 ; Malik et al, 2020 ), and the downregulation or inhibition of this pathway has been found to contribute to the protective strategy ( Shah et al, 2019 ). We observed similar activities in the APAP-intoxicated group, and carveol significantly reduced p-JNK expression.…”

“…Moreover, the expression of COX-2 and iNOS can be prevented by antagonizing p-NFκB expression ( Ali A et al, 2020 ). Natural drug substances have significant anti-inflammatory potential, and we previously showed the inhibitory effect of carveol, polydatin, and Ginkgo biloba on NFkB, COX-2, and iNOS expression in different experimental models ( Al Kury et al, 2019 ; Al Kury et al, 2020 ; Malik et al, 2020 ). We postulated here that carveol reduces hepatocellular necrosis by negatively modulating the expression of mitogen kinase and other inflammatory cytokines.…”

Repurposing FDA Approved Drugs as JNK3 Inhibitor for Prevention of Neuroinflammation Induced by MCAO in Rats

“…The absorbance was expressed in µmol GSH/g of the sample. To detect the GST activity, 42 a stock of 0.1 M potassium phosphate buffer was prepared using KHPO 4 and KH 2 PO 4 in a 1:2 ratio (pH 6.5). For the assay, 1 mM GST and 1 mM CDNB were prepared.…”

Taurine Protects against Postischemic Brain Injury via the Antioxidant Activity of Taurine Chloramine

“…At 24 h post-MCAO, the expression of antioxidants was induced, and Tau-Cl treatment during the acute phase (1 h post-MCAO) further enhanced this induction, possibly mitigating ischemic brain damage. However, contradictory results have been reported regarding the expression and activation of antioxidant enzymes in MCAO models, with some reporting increasing [ 61 , 62 ] and some decreasing expressions [ 63 , 64 ]. These contradictions might be caused by the experimental conditions, such as reperfusion time and brain region assayed.…”