Abstract

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Oyster mushrooms can synthesize great number of minerals, and secondary metabolites that possess antioxidant activities which play important role in maintaining human health. This study investigated the proximate, mineral and antioxidant properties of Pleurotus ostreatus cultivated on medicinal leaves such as Neem leaves (Azadirachta indica), Moringa leaves (Moringa oleifera), Lemon grass (Cymbopogon citratus), Scent leaves (Ocimum gratissimum) and oil palm fibre as control. Spawns of P. ostreatus were cultivated on medicinal leaves (substrates), Proximate and mineral content were determine using standard chemical and spectrophotometric method. Results showed that the proximate composition (%) of P. ostreatus cultivated on A. indica, M. oleifera and C. citratus had highest values of 15.20±0.09d, 17.35±0.42e and 4.47±0.06c for moisture, protein, and lipid contents respectively while highest 45.90±0.53a, 22.30±0.43b and 15.97±0.11c were recorded for carbohydrate, crude fibre and total ash contents respectively in P. ostreatus cultivated on oil palm. Mineral composition (mg/100g) revealed that P. ostreatus cultivated on M. oleifera had highest 11.12, 17.87, 8.22 and 7.34 for Sodium, Calcium, Iron and Zinc respectively. Total phenolic, vitamin C content, Ferric Reducing ability, hydroxyl radicals scavenging ability, Iron chelating ability, Nitric oxide (%) activities, free radical scavenging activity and ABTS scavenging ability had highest values of 33.348mg, 91.252 mg/100g, 2.808 mg/ml, 82.014% 42.616%, 72.180%, 67.256% and 0.024 mg/ml respectively in aqueous extracts while flavonoids contents had highest 0.804mg in ethanoic extracts of P. ostreatus cultivated on M. oleifera leaves. It can be concluded that substrates used in this study improved the nutraceutical properties of P. ostreatus.

Keywords: Pleurotus ostreatus, medicinal plant leaves, proximate, mineral content and antioxidant