Abstract
Amauroderma rugosum, commonly known as “Jiǎzī” in China, is a wild mushroom traditionally used by the Chinese to reduce inflammation, to treat diuretic and upset stomach, and to prevent cancer. It is also used by the indigenous communities in Malaysia to prevent epileptic episodes and incessant crying by babies. The aim of this study was to compare the wild and domesticated basidiocarps of A. rugosum for antioxidant and in vitro anti-inflammatory effects in LPS-stimulated RAW264.7 cells. The wild basidiocarps of A. rugosum were collected from the Belum Forest, Perak, Malaysia and the domesticated basidiocarps of A. rugosum were cultivated in the mushroom house located in the University of Malaya, Kuala Lumpur, Malaysia. Both the wild and domesticated basidiocarps were subjected to ethanolic extraction and the extracts were tested for antioxidant and anti-inflammatory activities. In this study, the crude ethanolic extract of wild (WB) and domesticated (DB) basidiocarps of A. rugosum had comparable total phenolic content and DPPH scavenging activity. However, WB (EC50 = 222.90 μg/mL) displayed a better ABTS cation radical scavenging activity than DB (EC50 = 469.60 μg/mL). Both WB and DB were able to scavenge nitric oxide (NO) radical and suppress the NO production in LPS-stimulated RAW264.7 cells and this effect was mediated through the down-regulation of inducible nitric oxide synthase (iNOS) gene. In addition, both WB and DB caused down-regulation of the inflammatory gene TNF-α and the up-regulation of the anti-inflammatory gene IL-10. There was no inhibitory effect of WB and DB on nuclear translocation of NF-κB p65. In conclusion, the wild and domesticated basidiocarps of A. rugosum possessed antioxidant and in vitro anti-inflammatory properties. WB and DB inhibited downstream inflammatory mediators (TNF-α and NO) and induced anti-inflammatory cytokine IL-10 production. No inhibitory effects shown on upstream nuclear translocation of NF-κB p65. WB and DB exhibited antioxidant activity and attenuation of proinflammatory mediators and therefore, A. rugosum may serve as a potential therapeutic agent in the management of inflammation.
Highlights
Reactive oxygen species (ROS) are products of normal cellular metabolism
We have reported that the mycelium of A. rugosum grown in submerged culture is a good source of nutrients and the hexane fraction has potential antioxidant and anti-inflammatory activities [16]
Dimethyl sulfoxide (DMSO) was purchased from Fisher Scientific Inc. (New Hampshire, USA) and 2, 2-Diphenyl-1-picrylhydrazyl (DPPH), ascorbic acid, trolox, butylated hydroxytoluene (BHT), gallic acid, Dulbecco’s Modified Eagle’s Medium (DMEM), foetal bovine serum (FBS), Escherichia coli (O55:B5) lipopolysaccharide (LPS), Nω-nitro-l-argininemethyl ester (L-NAME), sulphanilamide, N-1(1-napthyl)ethylenediamine, phosphoric acid (H3PO4), quercetin, triton X-100, and sodium nitroprusside were obtained from SigmaAldrich
Summary
The products of partial reduction of oxygen such as superoxide anion radical (O-2), hydroperoxyl radical (HOO·) and hydroxyl radical (·OH) are highly reactive [1] These reactive molecules play an important role in the defence against microbial pathogens [2]. Macrophages are activated by proinflammatory mediators such as lipopolysaccharide (LPS), interleukin-1β (IL-1β), and interferon-γ (IFN-γ) by binding to toll-like receptor-4 (TLR-4) which in turn activate the inflammatory signalling pathway nuclear factor kappa B (NF-κB) [6]. This subsequently stimulates the release of numerous proinflammatory mediators such as nitric oxide (NO), tumour necrosis factor-α (TNF-α), and interleukin-6 (IL-6) [6]. Biomarkers of inflammation may serve as important molecular targets for the development of potential anti-inflammatory drugs and may be used to facilitate diagnosis and management of inflammatory disorders and neurologic diseases such as epilepsy [7 – 8]
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