Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Food Science and Nutrition | en_US |
| dc.contributor.advisor | Wu, Jian-yong (FSN) | en_US |
| dc.creator | Zhu, Yanyu | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/14651 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Bioactive polysaccharide-protein complexes isolated from mycelial fermentation of medicinal fungus Cordyceps Cs-HK1 | en_US |
| dcterms.abstract | Inflammation, oxidative stress, and intestinal barrier dysfunction are closely interconnected in the development of many chronic disorders. Natural polysaccharide-protein (PSP) complexes from Cordyceps sinensis strain Cs-HK1 offer a sustainable source of multifunctional biomacromolecules with potential therapeutic and nutritional applications. This research systematically investigated two distinct types of PSPs: an extracellular PSP obtained from the liquid fermentation medium of Cs-HK1 (EPS-derived PSP), and an ultrasound-released PSP (US-PSP) derived from ultrasonic disruption of the mycelial fermentation broth, which releases intracellular PSP conjugates that combine with extracellular components. | en_US |
| dcterms.abstract | The EPS-derived PSP was fractionated by stepwise ethanol precipitation. After the high-molecular-weight fraction was precipitated at 40% ethanol (v/v), additional ethanol was added to the supernatant to a final concentration of 80% (v/v) to recover the low-molecular-weight fraction (EPS-LM). EPS-LM had an average molecular weight of 6.58 × 10⁵ Da and consisted of polysaccharide and protein components forming a typical polysaccharide-protein complex. In RAW264.7 macrophages, EPS-LM demonstrated potent anti-inflammatory and antioxidant activities by suppressing LPS-induced nitric oxide and reactive oxygen species production and inhibiting activation of the TLR4/MyD88/NF-κB signaling pathway. Co-immunoprecipitation analysis further confirmed that EPS-LM disrupted the association between TLR4 and MyD88, thereby suppressing downstream inflammatory signaling and cytokine production. | en_US |
| dcterms.abstract | Further evaluation in Caco-2 epithelial cells revealed that EPS-LM effectively mitigated H₂O₂-induced oxidative stress, restored the activities of antioxidant enzymes (SOD, GSH-Px, CAT), and normalized NRF2-NQO1 redox signaling. It also reinforced epithelial barrier integrity, as evidenced by increased transepithelial electrical resistance, reduced fluorescein permeability, and upregulated expression of tight-junction proteins (Occludin, ZO-1, and Claudin-1). Activation of the ERK signaling pathway enhanced the stability of these junctions, indicating the potential of EPS-derived PSP as a functional ingredient for intestinal health. | en_US |
| dcterms.abstract | To extend the functional applications of Cs-HK1-derived PSPs, the ultrasound-released PSP (US-PSP) was obtained through ultrasonic disruption of the mycelial fermentation broth, followed by enrichment using an alkali-solubilization and acid-precipitation method. The resulting US-PSP fraction was then utilized to develop a pH-induced, solvent-free quercetin-PSP complex as a natural carrier for poorly water-soluble flavonoids. The complex exhibited a uniform particle size, high encapsulation efficiency, and excellent thermal and ionic stability. Spectroscopic analyses confirmed that hydrogen bonding and hydrophobic interactions were the major driving forces for complex formation. Complexation with PSP significantly enhanced the antioxidant and anti-inflammatory activities of quercetin and increased its intestinal bioaccessibility to approximately 70%, nearly five times that of free quercetin under simulated gastrointestinal conditions. | en_US |
| dcterms.abstract | In conclusion, Cs-HK1-derived PSP complexes demonstrate dual bio-functional and delivery potential. The EPS-derived PSP functions as a potent anti-inflammatory, antioxidant, and barrier-protective agent, while the US-PSP serves as an effective biocompatible carrier that improves the stability, activity, and bioavailability of hydrophobic nutraceuticals such as quercetin. These findings provide fundamental and applied insights into the development of PSP-based functional foods, nutraceutical formulations, and health products targeting inflammation, oxidative stress, and intestinal health. | en_US |
| dcterms.extent | xix, 181 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2026 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.accessRights | open access | en_US |
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