Phyllanthin Averts Oxidative Stress and Neuroinflammation in Cerebral Ischemic-Reperfusion Injury through Modulation of the NF-κB and AMPK/Nrf2 Pathways.

Abstract

Cerebral ischemia-reperfusion (CIR) is a common feature of ischemic stroke and is a major cause of disability and death among stroke patients worldwide. Phyllanthin, a lignin polyphenol, is known for its varied biological properties, although its protective effects against CIR have not been reported. We evaluated the neuroprotective property of phyllanthin against CIR as well as the involvement of the AMP-activated protein kinase/nuclear factor erythroid 2-related factor 2 (AMPK/Nrf2) and nuclear factor kappa B (NF-κB) signaling pathways. Experimental animals were divided into five groups: controls (sham-operated), CIR-induced by middle cerebral artery occlusion (MCAO), and CIR-induced and administered phyllanthin at 2.5, 5, and 10 mg/kg, respectively. We investigated neurological functions, various signaling genes, and inflammatory clues. The results of in vitro assays demonstrated that phyllanthin assertively improved cellular functions through abrogation of the Nrf2 pathway. In vivo, CIR rats demonstrated neurological function deficits, while ischemic severity was evidenced by the activation of neuroinflammatory cytokines and tissue oxidative stress. Moreover, the expression of apoptosis markers such as Bax, B-cell lymphoma (Bcl-2), caspase-3, COX-2, PGE2, and LOX-1 abruptly increased. Phyllanthin prevented brain dysfunction and cerebral edema, and protected brain integrity. Conversely, it improved antioxidative enzyme activity, abrogated inflammatory cytokines, and increased IL-10 in chemokines. Also, phyllanthin significantly reduced Nrf2 and AMPK levels, with reduced expression of NF-κB indicating that cross-talk between the NF-kB and Nrf2 pathways is activated in CIR. Phyllanthin rescues the ischemic brain by regulating cellular signaling, which supports its use for complications like CIR and associated injury.