Effect of particle size on β-glucan content, antioxidant and anti-inflammatory properties of Pleurotus floridanus / Wong Wei Yan

Wong , Wei Yan (2024) Effect of particle size on β-glucan content, antioxidant and anti-inflammatory properties of Pleurotus floridanus / Wong Wei Yan. Masters thesis, Universiti Malaya.

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Abstract

Cellular damage caused by high concentrations of free radicals can lead to chronic health problems. Pleurotus floridanus is an edible white oyster mushroom that contains high β-glucan with antioxidant and anti-inflammatory potential. In this study, β-glucan, total phenolic content, antioxidant and anti-inflammatory potential of hot water extract with different particles sizes which were <75 μm, 75-154 μm, 154-300 μm and 300-600 μm of the whole (AW) and sliced (AS) fruiting body of P. floridanus were analysed. All particle sizes of AS of P. floridanus extract have higher β-glucan content compared to AW. Results showed that β-glucan content increased as the particle size increased but no significant difference was observed. For the total phenolic content, particle size <75 μm of AW and AS of P. floridanus has the highest phenolic content. Antioxidant potential of P. floridanus extract was determined using DPPH (2,2-Diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and ferric reducing antioxidant power (FRAP) assays. Each particle size of AW and AS of P. floridanus displayed potent scavenging activities toward DPPH and ABTS radicals in a concentration dependent manner. Both DPPH and ABTS assays showed that smaller particle size has higher scavenging activity compared to larger particle sizes. For FRAP assay, although there were fluctuations in the result but all the particle size of AW and AS of P. floridanus extract possess the ability to reduce Fe3+ to Fe2+. Four samples (AW2, AW3, AS1 and AS2) with the highest antioxidant activity were selected for anti-inflammatory assay. The ability of AW2, AW3, AS1 and AS2 to inhibit NO production, NO radical scavenging activity, TNF-α and IL-10 production in LPS-stimulated RAW264.7 cells was evaluated. All four samples reduced NO and TNF-α but did not enhance IL-10 expression in LPS-stimulated RAW264.7 cells. It was also observed that the particle size <75-300 μm lacked anti-inflammatory activity. Therefore, it is suggested that the particle size <300 μm of P. floridanus hot water extract could be a good source of antioxidant and anti-inflammatory compounds to counteract the free radicals. These results demonstrate how the sieving process can boost the bioactive compounds found in P. floridanus powder. This understanding holds significance for the food and pharmaceutical sectors, as it enables the creation of products with specific particle size fractions, maximizing both functional and nutritional benefits.

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