Nutraceutical Potential of Lentinula edodes' Spent Mushroom Substrate: A Comprehensive Study on Phenolic Composition, Antioxidant Activity, and Antibacterial Effects

Abstract

Lentinula edodes, commonly known as shiitake mushroom, is renowned for its potential health advantages. This research delves into the often-overlooked by-product of shiitake cultivation, namely spent mushroom substrate (SMS), to explore its nutraceutical properties. The SMS samples were collected and subjected to different extraction methods, namely short or long agitation, and ultrasound-assisted extractions using different temperatures and distilled water or a 50% (v/v) ethanol as solvents. The extracts were tested for phenolic content (total phenols, ortho-diphenols, and flavonoids), antioxidant capacity (DPPH, 2,2-diphenyl-1 picrylhydrazyl; ABTS, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid; and FRAP, ferric reducing antioxidant power), and antibacterial activity. The different extraction methods revealed substantial variations (p < 0.05) in phenolic composition and antioxidant capacity. The highest phenolic content and antioxidant capacity were achieved using 24 h extraction, agitation, 50 °C, and ethanol as the solvent. Furthermore, the extracted compounds displayed antibacterial activity in specific tested bacterial strains. This study highlights the nutraceutical potential of L. edodes' SMS, positioning it as a valuable dietary supplement for animal nutrition, with emphasis on its prebiotic properties. Hence, this research unveils the promising health benefits of SMS in both human and animal nutrition.

Keywords: Lentinula edodes; circular economy; extraction methods; nutraceuticals; prebiotic supplementation; spent mushroom substrate; valuable by-product resources.

Figure 1

Use of spent mushroom substrate (SMS) in a circular economy context.

Figure 2

Schematic representation of the methodology used in this study. ABTS—2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt; DPPH—2,2-Diphenyl-1-picrylhydrazyl; FRAP—ferric-reducing antioxidant power; w—distilled water; et—ethanol 50% (v/v) solvent; SE—short extraction; LE—24 h extraction; LE-HT—24 h extraction with high temperature; UE—ultrasound extraction; COMB—combined methods (LE + UE); COMB-HT—combined methods (LE-HT + UE).

Figure 3

Correlation analysis of the variables phenolic content and antioxidant capacity. (A) PCA, (B) heatmap. w—distilled water; et—ethanol 50% (v/v) solvent; SE—short extraction; LE—24 h extraction; LE-HT—24 h extraction with high temperature; UE—ultrasound extraction; COMB—combined methods (LE + UE); COMB-HT—combined methods (LE-HT + UE). ABTS—2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt; DPPH—2,2-Diphenyl-1-picrylhydrazyl; FRAP—ferric-reducing antioxidant power; TPC—total phenols; ODC—ortho-diphenols; FC—flavonoids. ***, p-value < 0.001; **, p-value < 0.01; *, p-value < 0.05.

Figure 4

Correlation analysis of the variables phenolic content and antibacterial activity. (A) PCA, (B) heatmap. w—distilled water; et—ethanol 50% (v/v) solvent; SE—short extraction; LE—24 h extraction; LE-HT—24 h extraction with high temperature; UE—ultrasound extraction; COMB—combined methods (LE + UE); COMB-HT—combined methods (LE-HT + UE). ABTS—2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt; DPPH—2,2-Diphenyl-1-picrylhydrazyl; FRAP—ferric reducing antioxidant power; TPC—total phenols; ODC—ortho-diphenols; FC—flavonoids. ***, p-value < 0.001; *, p-value < 0.05.