A. Buddhika G. Silva. Preparation and identification of anti-inflammatory peptides derived from Yamabushitake (Hericium erinaceus) mushroom proteins. Master's Degree(Food Science and Technology). Chiang Mai University. Library. : Chiang Mai University, 2024.
Preparation and identification of anti-inflammatory peptides derived from Yamabushitake (Hericium erinaceus) mushroom proteins
Abstract:
Yamabushitake (Hericium erinaceus)-HE is globally recognized as one of the most important medicinal mushrooms. HE proteins have gained much attention, especially in relation to the bioactive properties. Among bioactive properties, anti-inflammatory activity gains prime importance since prolonged inflammation as well as anti-inflammatory synthetic drugs lead to serious health complications. Therefore, the main objective of this study was to investigate potential anti-inflammatory bioactive peptides from Yamabushitake (Hericium erinaceus) mushrooms. Proteins were extracted by using pulsed electric field (PEF)-assisted alkaline extraction with varied electric field strengths (5 kV/cm, 10 kV/cm) and pulse numbers (10000, 15000, 20000, 25000 pulses). The derived total protein content was compared to the conventional alkaline extraction. The extracted protein was characterized in terms of amino acid profile, amino acid score (AAS), digestibility, and protein digestibility corrected amino acid score (PDCAAS). After that, the protein was further hydrolyzed under the in vitro gastrointestinal (GI) tract. Three fractions (unhydrolyzed, pepsin hydrolyzed, and pepsin-trypsin hydrolyzed) were evaluated for anti-inflammatory activity. The most effective fraction was chosen to fractionate using membrane ultrafiltration (3-10 kDa) and size exclusion chromatography. The fraction possessing the highest potential for anti-inflammatory activity was investigated to confirm the peptide sequences. The optimized PEF-assisted extraction for HE protein, including 5 kV/cm of electric field strength and 25,000 pulses, provided higher extraction efficiency by 42.44% than conventional alkaline treatment. Essential amino acid content was 44.59% of total amino acids, with lysine and sulfur-containing amino acids as limiting amino acids in HE proteins, and digestibility was found to be 71.33±0.30%. Pepsin-trypsin hydrolysis stimulated the most potent anti-inflammatory activity that significantly decreased the formation of nitric oxide (NO) and interleukin-6 (IL-6) by 36.2% and 31.8%, respectively (p < 0.05) After membrane ultrafiltration, peptides with >10 kDa showed the highest anti-inflammatory activity by reducing NO and IL-6 formation with values of 34.85% and 46.11%, respectively (p < 0.05) Three fractions were collected from size exclusion chromatography, and nine major peptide sequences were identified from those three fractions by LC-MS/MS with 6-9 amino acids, including LLLFRNKN, LLLKKSL, LLEAWSL, LLLKVKT, VVGPLAKSA, LLLLLLLL, SL L LYLLFGV, ELALVVKN, and KNFLFR. The identified nine peptides are composed of 50-100% hydrophobic amino acids. Leucine, which was the most abundant amino acid, existed in all sequences, followed by lysine and valine. These findings uncover the effective integration of in vitro gastrointestinal digestion and fractionation for producing anti-inflammatory peptides from Yamabushitake mushroom proteins for applications as a functional food ingredient or nutraceuticals.