Centesimal Composition, Bioactive Compounds, Antioxidant and α-Glucosidase Inhibitory Activities of Commercial Edible Oyster Mushrooms at Different Maturity Stages in Northern Thailand

Oyster mushrooms (<i>Pleurotus</i> spp.) are widely cultivated due to their high nutritional value and bioactive compounds with health-promoting properties. However, the fruiting body developmental stage significantly influences the centesimal composition and bioactive compound levels. This study examined the centesimal composition and bioactive properties of five commercial oyster mushroom species (<i>P. citrinopileatus</i>, <i>P. cornucopiae</i>, <i>P. djamor</i>, <i>P. ostreatus</i>, and <i>P. pulmonarius</i>) cultivated in northern Thailand at three maturation stages (young, middle, and mature). The centesimal composition; polysaccharide, ergothioneine, and phenolic compound contents; antioxidant activity; and α-glucosidase inhibitory activity were analyzed. The results showed that the centesimal composition and polysaccharide content increased as the mushrooms matured in all species. The middle stage consistently exhibited the highest levels of ergothioneine, total phenolics, and individual phenolic compounds in all five species. Twelve phenolic compounds were identified, with 4-hydroxybenzoic acid, trans-cinnamic acid, and trans-o-coumaric acid being predominant. All extracts exhibited antioxidant activity, according to the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) assays, and α-glucosidase inhibitory activity, with the highest activity found at the middle stage. This is the first paper to report the ergothioneine content and <i>α</i>-glucosidase inhibitory activity in <i>P. cornucopiae</i> and <i>P. djamor</i>. These findings demonstrate that harvest timing can be optimized to maximize either the nutritional content (mature stage) or bioactive compound content for functional food applications (middle stage), offering a better understanding of the developmental phases at which mushrooms have the greatest health and technological potential. Furthermore, this knowledge provides practical guidance for growers seeking to target specific markets for high nutritional value foods based on consumer demand and for functional food developers aiming to maximize health-promoting properties.