4-O-carboxymethylascochlorin protected against microglial-mediated neurotoxicity in SH-SY5Y and BV2 cocultured cells from LPS–induced neuroinflammation and death by inhibiting MAPK, NF-κB, and Akt pathways

In our previous studies, structurally similar compounds of ascochlorin and ascofuranone exhibited anti-inflammatory activity. Neural inflammation plays a significant role in the commence and advancement of neurodegenerative diseases. It is not known whether 4-O-carboxymethylascochlorin (AS-6) regulates the initial stage of inflammatory responses at the cellular level in BV2 microglia cells. We here investigated the anti-inflammatory effects of AS-6 treatment in microglia cells with the microglial protection in neurons. We found that the lipopolysaccharide (LPS)-stimulated production of nitric oxide, a main regulator of inflammation, is suppressed by AS-6 in BV2 microglial cells. In addition, AS-6 dose-dependently suppressed the increase in COX-2 protein and messenger RNA levels in LPS-stimulated BV2 cells. Moreover, AS-6 inhibited the expression and secretion of proinflammatory cytokines in BV2 microglial cells. At the intracellular level, AS-6 inhibited LPS-activated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in BV2 microglial cells. AS-6 negatively affected mitogen-activated protein kinases (MAPK) and Akt phosphorylation: Phosphorylated forms of ERK, JNK, p38, and Akt decreased. To check whether AS-6 protects against inflammatory inducer-mediated neurotoxicity, neuronal SH-SY5Y cells were coincubated with BV2 cells in conditioned medium. AS-6 exerted a neuroprotective effect by suppressing microglial activation by LPS or amyloid-β peptide. AS-6 is a promising suppressor of inflammatory responses in LPS-induced BV2 cells by attenuating NF-κB and MAPKs signaling. AS-6 protected against microglial-mediated neurotoxicity in SH-SY5Y and BV2 cocultured cells from LPS–induced neuroinflammation and death via inhibiting MAPK, NF-κB, and Akt pathways.