Edible and medicinal mushrooms are regularly used in natural medicines and home remedies since antiquity for ailments like fever, inflammation, and respiratory disorders. Lignosus rhinocerotis (Cooke) Ryvarden is a polypore found in Malaysia and other regions in South East Asia. It can be located on a spot where a tigress drips milk while feeding, hence the name “tiger's milk mushroom.” The sclerotium of L. rhinocerotis is highly sought after by the native communities in Malaysia to stave off hunger, relieve cough and asthma, and provide stamina. The genomic features of L. rhinocerotis have been described. The pharmacological and toxicity effects, if any, of L. rhinocerotis sclerotium have been scientifically verified in recent years. In this review, the validated investigations including the cognitive function, neuroprotection, immune modulation, anti-asthmatic, anti-coagulation, anti-inflammatory, anti-microbial/ anti-viral, anti-obesity, anti-cancer/ anti-tumor, and antioxidant properties are highlighted. These findings suggest that L. rhinocerotis can be considered as an alternative and natural medicine in the management of non-communicable diseases. However, there is a paucity of validation studies including human clinical trials of the mycochemicals of L. rhinocerotis.

BackgroundSenescence of the neurons is believed to be a focal factor in the development of age-related neurodegenerative diseases such as Alzheimer’s disease. Diminutions in the levels of nerve growth factor (NGF) lead to major declines in brain cell performance. Functional foods, believed to mitigate this deficiency, will be reaching a plateau in the near future market of alternative and preventive medicine. In the search for neuroactive compounds that mimic the NGF activity for the prevention of neurodegenerative diseases, the potential medicinal values of culinary and medicinal mushrooms attract intense interest.MethodsCytotoxic effects of aqueous extracts of three medicinal mushrooms basidiocarps, Ganoderma lucidum, Ganoderma neo-japonicum and Grifola frondosa towards rat pheochromocytoma (PC-12) cells were determined by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The potentiation of neuritogenic activity was assessed by neurite outgrowth stimulation assay. Involvement of cellular signaling pathways, mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK1/2) and phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) in mushrooms-stimulated neuritogenesis were examined by using specific pharmacological inhibitors. Alteration of neuronal morphology by inhibitors was visualized by immunofluorescence staining of the neurofilament.ResultsAll the aqueous extracts tested caused a marked stimulation of neuritogenesis with no detectable cytotoxic effects towards PC-12 cells. The aqueous extract of G. neo-japonicum triggered maximal stimulation of neurite outgrowth at a lower concentration (50 μg/ml) with 14.22 ± 0.43% of neurite-bearing cells, compared to G. lucidum and G. frondosa that act at a higher concentration (75 μg/ml), with 12.61 ± 0.11% and 12.07 ± 0.46% of neurite-bearing cells, respectively. The activation of MEK/ERK1/2 and PI3K/Akt signaling pathways were necessary for the NGF and aqueous extracts to promote neuritogenesis.ConclusionsGanoderma lucidum, G. neo-japonicum and G. frondosa may contain NGF-like bioactive compound(s) for maintaining and regenerating the neuronal communications network. The present study reports the first evidence of the neuritogenic effects of aqueous extracts of basidiocarps of G. neo-japonicum in-vitro and showed the involvement of MEK/ERK1/2 and P13K/Akt signaling pathways for neuritogenesis in PC-12 cells.

The traditional application of the sclerotium of Lignosus rhinocerotis (tiger’s milk mushroom) by the indigenous folks as tonic and remedy to treat a variety of ailments has been documented in Malaysia. Indigenous communities claimed to have consumed the decoction to boost their alertness during hunting. Mental alertness is believed to be related to neuronal health and neuroactivity. In the present study, the cell viability and neuritogenic effects of L. rhinocerotis sclerotium hot aqueous and ethanolic extracts, and crude polysaccharides on rat pheochromocytoma (PC-12) cells were studied. Interestingly, the hot aqueous extract exhibited neuritogenic activity comparable to NGF in PC-12 cells. However, the extracts and crude polysaccharides stimulated neuritogenesis without stimulating the production of NGF in PC-12 cells. The involvements of the TrkA receptor and MEK/ERK1/2 pathway in hot aqueous extract-stimulated neuritogenesis were examined by Trk (K252a) and MEK/ERK1/2 (U0126 and PD98059) inhibitors. There was no significant difference in protein expression in NGF- and hot aqueous extract-treated cells for both total and phosphorylated p44/42 MAPK. The neuritogenic activity in PC-12 cells stimulated by hot aqueous and ethanolic extracts, and crude polysaccharides of L. rhinocerotis sclerotium mimicking NGF activity via the MEK/ERK1/2 signaling pathway is reported for the first time.

In Malaysia and China, the sclerotium of Lignosus rhinocerotis is used by local communities and traditional medicine practitioners as a general tonic and remedy to treat a variety of ailments, including inflammation-associated disorders. In this study, 10 samples from different preparations of L. rhinocerotis sclerotium, including a hot aqueous extract (HAE), an ethanol extract (EE), fractions from the HAE and EE, and crude polysaccharides, were tested for their in vitro cytotoxic and nitric oxide (NO) inhibitory activities in lipopolysaccharide (LPS)--stimulated BV2 microglia. Of the 10 samples tested, HAE was the least cytotoxic toward BV2 microglia, with a half-maximal inhibitory concentration of 176.23 ± 2.64 mg/mL at 24 hours of incubation and 20.01 ± 1.69 mg/ mL at 48 hours of incubation. The inhibition of NO production was explored by pretreatment of BV2 microglia with samples at 2 incubation time points (4 and 24 hours) before the stimulation by LPS for 24 hours. After 24 hours of pretreatment, 8 of the 10 samples inhibited NO production by 50% or more, and cytotoxic effects were not observed. Among the 8 active samples, 500 µg/mL of HAE, 250 µg/mL of an n-butanol fraction of the HAE, and 250 µg/mL of an ethyl acetate fraction of HAE showed maximum inhibition of NO production by 88.95%, 86.50%, and 85.93%, respectively. These results suggest that the L. rhinocerotis sclerotium may contain secondary metabolites that have the potential to inhibit NO production.