Aqueous extracts of Ganoderma lucidum, Lignosus rhinocerotis, Pleurotus giganteus

31 Background 32 Mushrooms are not only regarded as gourmet cuisine but also as therapeutic agent to 33 promote cognition health. However, little toxicological information is available regarding 34 their safety. Therefore, the aim of this study was to screen selected ethno35 pharmacologically important mushrooms for stimulatory effects on neurite outgrowth and 36 to test for any cytotoxicity. 37 Methods 38 The stimulatory effect of mushrooms on neurite outgrowth was assessed in differentiating 39 mouse neuroblastoma (N2a) cells. Neurite length was measured using Image-Pro Insight 40 processor system. Neuritogenesis activity was further validated by fluorescence 41 immunocytochemical staining of neurofilaments. In vitro cytotoxicity was investigated 42 by using mouse embryonic fibroblast (BALB/3T3) and N2a cells for any embryoand 43 neuro-toxic effects; respectively. 44 Results 45 Aqueous extracts of Ganoderma lucidum, Lignosus rhinocerotis, Pleurotus giganteus and 46 Grifola frondosa; as well as an ethanol extract of Cordyceps militaris significantly (p < 47 0.05) promoted the neurite outgrowth in N2a cells by 38.4 ± 4.2%, 38.1 ± 2.6%, 33.4 ± 48 4.6%, 33.7 ± 1.5%, and 35.8 ± 3.4%; respectively. The IC50 values obtained from 49 tetrazolium (MTT), neutral red uptake (NRU) and lactate dehydrogenase (LDH) release 50 assays showed no toxic effects following 24 h exposure of N2a and 3T3 cells to 51 mushroom extracts. 52 Conclusion 53 Our results indicate that G. lucidum, L. rhinocerotis, P. giganteus, G. frondosa and C. 54 militaris may be developed as safe and healthy dietary supplements for brain and 55 cognitive health. 56 57