mushroom’s aqueous and ethanolic extracts towards PC12, a rat pheochromocytoma cell line

32 Background 33 Drugs dedicated to alleviate neurodegenerative diseases like Parkinson’s and Alzheimer’s have 34 always been associated with debilitating side effects. Medicinal mushrooms which harness 35 neuropharmacological compounds offer a potential possibility for protection against such 36 diseases. Pleurotus giganteus (formerly known as Panus giganteus) has been consumed by the 37 indigenous people in Peninsular Malaysia for many years. Domestication of this wild mushroom 38 is gaining popularity but to our knowledge, medicinal properties reported for this culinary 39 mushroom are minimal. 40 Methods 41 The fruiting bodies P. giganteus were analysed for its nutritional values. Cytotoxicity of the 42 mushroom’s aqueous and ethanolic extracts towards PC12, a rat pheochromocytoma cell line 43 was assessed by using 3-[4,5-dimethythiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) 44 assay. Neurite outgrowth stimulation assay was carried out with nerve growth factor (NGF) as 45 control. To elucidate signaling mechanisms involved by mushroom extract-induced neurite 46 outgrowth, treatment of specific inhibitor for MEK/ERK and PI3K signalling pathway was 47 carried out. 48 Results 49 The fruiting bodies of P. giganteus were found to have high carbohydrate, dietary fibre, 50 potassium, phenolic compounds and triterpenoids. Both aqueous and ethanolic extracts induced 51 neurite outgrowth of PC12 cells in a doseand time-dependant manner with no detectable 52 cytotoxic effect. At day 3, 25 μg/ml of aqueous extract and 15 μg/ml of ethanolic extract showed 53 the highest percentage of neurite-bearing cells, i.e. 31.7 ± 1.1% and 33.3 ± 0.9%; respectively. 54 Inhibition treatment results suggested that MEK/ERK and PI3K/Akt are responsible for neurite 55 outgrowth of PC12 cells stimulated by P. giganteus extract. The high potassium content (1345.7 56 mg/100 g) may be responsible for promoting neurite extension, too. 57 Conclusion 58 P. giganteus contains bioactive compounds that mimic NGF and are responsible for neurite 59 stimulation. Hence, this mushroom may be developed as a nutraceutical for the mitigation of 60 neurodegenerative diseases. 61