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.
Highlights
Free radicals are important in the regulation gene expression and activation of receptors
Results from the Gas chromatography-mass spectrometry (GC-MS) analysis are presented in Table II and Figure 3
Many mushrooms analysed in previous studies had linoleic and palmitic acids as the most abundant fatty acids (Gunc-Ergönül et al, 2013)
Summary
Free radicals are important in the regulation gene expression and activation of receptors. Inflammation of the brain is characterised by the activation of glial cells (mainly microglial and astrocytes), expression of inflammatory mediators, and release of neurotoxic free radicals (Chen et al, 2016). This phenomenon is collectively known as “neuroinflammation”. This study is aimed towards elucidating the bioactive fraction of ethyl acetate (TE3) fraction of L. rhinocerotis with respect to its a) chemical components; b) cytotoxicity and the inhibition of nitric oxide (NO) production in BV2 cells; and c) effects on gene expression in the nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway
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