(+)-Catechin is a flavanol that possesses various health and medicinal values, which include neuroprotection, anti-oxidation, antitumor and antihepatitis activities. This study investigated the modulatory effects of (+)-catechin on the lipopolysaccharides (LPS)-stimulated BV-2 cells. (+)-catechin attenuated LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and inhibited microglial NO and ROS production. Additionally, (+)-catechin suppressed the production of tumor necrosis factor-α (TNF-α) and interleukin (IL)-6, while augmenting IL-4. (+)-catechin attenuated LPS-induced nuclear factor-κB (NF-κB) p65 nuclear translocation via the inhibition of IκB-α phosphorylation. Moreover, (+)-catechin blocked the activation of Akt and its inhibition was shown to play a crucial role in LPS-induced inflammation in BV-2 microglial cells. (+)-catechin also attenuated the LPS-induced phosphorylation of extracellular signal-regulated kinase (ERK1/2), and p-38 mitogen activated protein kinases (p38 MAPK) and specific inhibitors of ERK1/2 (UO126) and p38 MAPK (SB202190) subsequently down-regulated the expression of the proinflammatory mediators iNOS and COX-2. Further mechanistic study revealed that (+)-catechin acted through the amelioration of the LPS-induced suppression of adenosine monophosphate-activated protein kinase (AMPK) activity. Taken together, our data indicate that (+)-catechin exhibits anti-inflammatory effects in BV-2 cells by suppressing the production of proinflammatory mediators and mitigation of NF-κB through Akt, ERK, p38 MAPK, and AMPK pathways.

Alpha-lipoic acid, a potent antioxidant with multifarious pharmacological benefits has been reported to be neuroprotective in several neuronal models and used to treat neurological disorders such as Alzheimer’s disease. Nonetheless, conclusive mechanisms of alpha-lipoic acid for its protective effects particularly in NG108-15 cells have never been investigated. In this study, the intricate neuroprotective molecular mechanisms by (R)-(+)-alpha-lipoic acid (R-LA) against H2O2-induced cell death in an in vitro model of neurodegeneration were elucidated. Pretreatment with R-LA (2 hours) significantly increased NG108-15 cell viability as compared to H2O2-treated cells and mitigated the induction of apoptosis as evidenced by Hoechst 33342/propidium iodide staining. R-LA (12.5–50 μM) aggrandized the reduced glutathione over glutathione disulfide ratio followed by a reduction in the intracellular reactive oxygen species level and an increase in mitochondrial membrane potential following H2O2 exposure. Moreover, pretreatment with R-LA stimulated the activation of PI3K-Akt through mTORC1 and mTORC2 components (mTOR, rictor and raptor) and production of antiinflammatory cytokine, IL-10 which led to the inactivation of glycogen synthase kinase-3β (GSK-3β) and reduction of both Bax/Bcl2 and Bax/Bcl-xL ratios, accompanied by inhibition of the cleaved caspase-3. Additionally, this observation was preceded by the suppression of NF-κβ p65 translocation and production of proinflammatory cytokines (IL-6 and TNF-α). The current findings accentuate new mechanistic insight of R-LA against apoptogenic and brain inflammatory factors in a neuronal model. These results further advocate the therapeutic potential of R-LA for the treatment of neurodegenerative diseases.