Mushrooms have long been used not only as food but also for the treatment of various ailments. Although at its infancy, accumulated evidence suggested that culinary-medicinal mushrooms may play an important role in the prevention of many age-associated neurological dysfunctions, including Alzheimer's and Parkinson's diseases. Therefore, efforts have been devoted to a search for more mushroom species that may improve memory and cognition functions. Such mushrooms include Hericium erinaceus, Ganoderma lucidum, Sarcodon spp., Antrodia camphorata, Pleurotus giganteus, Lignosus rhinocerotis, Grifola frondosa, and many more. Here, we review over 20 different brain-improving culinary-medicinal mushrooms and at least 80 different bioactive secondary metabolites isolated from them. The mushrooms (either extracts from basidiocarps/mycelia or isolated compounds) reduced beta amyloid-induced neurotoxicity and had anti-acetylcholinesterase, neurite outgrowth stimulation, nerve growth factor (NGF) synthesis, neuroprotective, antioxidant, and anti-(neuro)inflammatory effects. The in vitro and in vivo studies on the molecular mechanisms responsible for the bioactive effects of mushrooms are also discussed. Mushrooms can be considered as useful therapeutic agents in the management and/or treatment of neurodegeneration diseases. However, this review focuses on in vitro evidence and clinical trials with humans are needed.

Hericium erinaceus (Bull.: Fr.) Pers. is an edible and medicinal mushroom used traditionally to improve memory. In this study, we investigated the neuritogenic effects of hericenones isolated from H. erinaceus and the mechanisms of action involved. H. erinaceus was cultivated and the secondary metabolites were elucidated by high performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), and nuclear magnetic resonance (NMR). The secondary metabolites were tested for neurite outgrowth activity (if any). Rat pheochromocytoma (PC12) cells were employed and the nerve growth factor (NGF) level was also determined. The signaling pathways involved in the mushroom-induced neuritogenesis were investigated using several pharmacological inhibitors. Hericenones B–E (1–4), erinacerin A (5) and isohericerin (6) were isolated from the basidiocarps of H. erinaceus. The hericenones did not promote neurite outgrowth but when induced with a low concentration of NGF (5 ng mL⁻¹), the neuritogenic activity was comparable to that of the positive control (50 ng mL⁻¹ of NGF). Hericenone E was able to stimulate NGF secretion which was two-fold higher than that of the positive control. The neuritogenesis process was partially blocked by the tyrosine kinase receptor (Trk) inhibitor, K252a, suggesting that the neuritogenic effect was not solely due to NGF. Hericenone E also increased the phosphorylation of extracellular-signal regulated kinases (ERKs) and protein kinase B (Akt). Taken together, this study suggests that hericenone E potentiated NGF-induced neuritogenesis in PC12 cells via the MEK/ERK and PI3K/Akt pathways.

Background: Mushrooms are not only regarded as gourmet cuisine but also as therapeutic agent to promote cognition health. However, little toxicological information is available regarding their safety. Therefore, the aim of this study was to screen selected ethno-pharmacologically important mushrooms for stimulatory effects on neurite outgrowth and to test for any cytotoxicity.Methods: The stimulatory effect of mushrooms on neurite outgrowth was assessed in differentiating mouse neuroblastoma (N2a) cells. Neurite length was measured using Image-Pro Insight processor system. Neuritogenesis activity was further validated by fluorescence immunocytochemical staining of neurofilaments.In vitrocytotoxicity was investigated by using mouse embryonic fibroblast (BALB/3T3) and N2a cells for any embryo- and neuro-toxic effects; respectively.Results: Aqueous extracts ofGanoderma lucidum,Lignosus rhinocerotis,Pleurotus giganteusandGrifola frondosa; as well as an ethanol extract ofCordyceps militarissignificantly (p < 0.05) promoted the neurite outgrowth in N2a cells by 38.4 ± 4.2%, 38.1 ± 2.6%, 33.4 ± 4.6%, 33.7 ± 1.5%, and 35.8 ± 3.4%; respectively. The IC₅₀values obtained from tetrazolium (MTT), neutral red uptake (NRU) and lactate dehydrogenase (LDH) release assays showed no toxic effects following 24 h exposure of N2a and 3T3 cells to mushroom extracts.Conclusion: Our results indicate thatG. lucidum,L. rhinocerotis,P. giganteus,G. frondosaandC. militarismay be developed as safe and healthy dietary supplements for brain and cognitive health.

Oxidative stress and inflammation in neuron-glia system are key factors in the pathogenesis of neurodegenerative diseases. As synthetic drugs may cause side effects, natural products have gained recognition for the prevention or management of diseases. In this study, hot water (HE-HWA) and ethanolic (HE-ETH) extracts of the basidiocarps of Hericium erinaceus mushroom were investigated for their neuroprotective and anti-inflammatory activities against hydrogen peroxide (H₂O₂)-induced neurotoxicity in HT22 mouse hippocampal neurons and lipopolysaccharide (LPS)-induced BV2 microglial activation respectively. HE-ETH showed potent neuroprotective activity by significantly (p < 0.0001) increasing the viability of H₂O₂-treated neurons. This was accompanied by significant reduction in reactive oxygen species (ROS) (p < 0.05) and improvement of the antioxidant enzyme catalase (CAT) (p < 0.05) and glutathione (GSH) content (p < 0.01). Besides, HE-ETH significantly improved mitochondrial membrane potential (MMP) (p < 0.05) and ATP production (p < 0.0001) while reducing mitochondrial toxicity (p < 0.001), Bcl-2-associated X (Bax) gene expression (p < 0.05) and nuclear apoptosis (p < 0.0001). However, gene expression of Nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1) and NAD(P)H quinone dehydrogenase 1 (NQO1) were unaffected (p > 0.05). HE-ETH also significantly (p < 0.0001) reduced nitric oxide (NO) level in LPS-treated BV2 indicating an anti-inflammatory activity in the microglia. These findings demonstrated HE-ETH maybe a potential neuroprotective and anti-inflammatory agent in neuron-glia environment.

There is an exponential increase in dementia in old age at a global level because of increasing life expectancy. The prevalence of neurodegenerative diseases such as dementia and Alzheimer's disease (AD) will continue to rise steadily, and is expected to reach 42 million cases worldwide in 2020. Despite the advancement of medication, the management of these diseases remains largely ineffective. Therefore, it is vital to explore novel nature-based nutraceuticals to mitigate AD and other age-related neurodegenerative disorders. Mushrooms and their extracts appear to hold many health benefits, including immune-modulating effects. A number of edible mushrooms have been shown to contain rare and exotic compounds that exhibit positive effects on brain cells both in vitro and in vivo. In this review, we summarize the scientific information on edible and culinary mushrooms with regard to their antidementia/AD active compounds and/or pharmacological test results. The bioactive components in these mushrooms and the underlying mechanism of their activities are discussed. In short, these mushrooms may be regarded as functional foods for the mitigation of neurodegenerative diseases.