Lipid-rich fraction of the sclerotium of Tiger Milk Mushroom Lignosus rhinocerotis (Agaricomycetes) attenuates LPS-induced inflammation in BV2 cells via Nrf2 pathway

Abstract

Lignosus rhinocerotis (tiger milk mushroom) is widely used by the indigenous people of Malaysia as a traditional remedy. The present study was carried out in order to evaluate the antioxidant, cytotoxic and anti-neuroinflammatory activities of L. rhinocerotis extract on brain microglial cells (BV2). The antioxidant activity was evaluated by 2,2-diphenyl-1-picryhydrazyl (DPPH•), 2,2’-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS•+) scavenging assays, and ferric reducing antioxidant power (FRAP). The FRAP, DPPH and ABTS•+ scavenging capacities of the TE3 fraction were 420.77 mg FE/g, 58.01%, and 7%, respectively. The cytotoxic activity was determined by MTS assay. The in vitro model of anti-neuroinflammatory property was evaluated by measuring the production of nitric oxide (NO) in lipopolysaccharide (LPS)-induced BV2 cells. The TE3 fraction showed a significant NO reduction at 1 to 100 µg/mL. The TE3 fraction down-regulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2) genes while it upregulated heme oxygenase (HO-1) and NADPH quinone acceptor oxidoreductase-1 (NQO-1) genes. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) transcription was also activated. The chemical component of the active fraction (TE3) was identified by gas chromatography-mass spectrometry (GCMS). Overall, the BV2 in vitro model anti-neuroinflammatory activity of L. rhinocerotis may be caused by the lipid constituents identified in the fraction.

Keywords

• Neuroinflammation
• Lignosus rhinocerotis
• Mushroom
• BV2 cells
• Nrf2 pathway