Enhanced antioxidant and anti-inflammatory activity of the extracts of Pleurotus ostreatus edible mushroom grown on Lavandula angustifolia residues

This study investigated the possibility to derive functional foods with enhanced bioactive properties from a recycling approach by using the residues from Lavandula angustifolia processing after essential oil extraction. The residues were used as a growing substrate for the edible mushroom Pleurotus ostreatus A strain, and they were added in a 30% proportion to a standard barley substrate. The metabolome of the mushroom grown on the lavender enriched substrate (named POA5) was obtained by parallel extraction with three solvents of decreasing polarity (i.e., methanol, ethanol, and acetonitrile), and these were compared to the ones obtained from the mushroom grown on pure barley substrate (POA1). The chemical characterization of the extracts was performed by HPLC-MS analysis clearly demonstrating a significant enrichment of potentially bioactive molecules in POA5 (from mushroom grown on lavender enriched substrate) as compared to POA1 (from mushroom grown on pure barley), especially in molecules with antioxidant and anti-inflammatory potential (polyphenols, tryptophan, hydroxy methyl coumarin, epoxy fatty acids). The biochemical and biomolecular analyses showed absence of cell toxicity on normal cell lines and a slight toxicity on some cancer cell lines and remarkably, an enhanced antioxidant, UV-protective, anti-inflammatory, and wound healing effect on skin HaCaT keratinocytes. Definitely, this work demonstrates the enrichment in bioactive molecules in the mushrooms grown on lavender residues-enriched substrates. This indicates the possibility to actively exploit this new circular economy strategy to produce functionally active mushrooms for direct consumption, or to exploit their derivatives for cosmetic formulations or oral supplement production.