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  • Author or Editor: X. Yang x
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Abstract

This study aimed to explore the inhibitory effect and mechanism of the total alkaloids of Dendrobium officinale Kimura et Migo (DENA) against cholesterol esterase (CE). DENA was characterised by SEM, 1H NMR, and X-ray diffraction (XRD). The inhibitory effect and mechanism of DENA against CE were investigated through fluorescence chromatography, circular dichroism, and molecular docking. DENA inhibited CE activity (IC50 = 1.08 ± 0.09 mg mL−1), characterised by a non-competitive inhibition mechanism. Furthermore, DENA induced a fluorescence quenching in CE, causing a blue shift in the λmax. This coincided with a transition in the secondary structure of CE from a layered to a helical structure by circular dichroism, indicating a significant reduction in its stability. Moreover, molecular docking confirmed that DENA binds to amino acid residues in the enzyme through hydrogen bonds and hydrophobic interactions, leading to structural changes and reduced enzyme activity. These results suggest DENA has the potential to lower blood lipid levels by inhibiting CE activity.

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Abstract

Conversion of economic microcrystalline cellulose (MCC) into high value-added prebiotic glucans, is not only stimulates utilisation of renewable lignocellulosic biomass, but also provides cheap prebiotics to reduce high incidence of obesity and metabolic syndrome. Herein, glucans (C0.25–C0.50–C1.00) from MCC were prepared by pre-impregnation with dilute sulphuric acid (0.25–0.50–1.00%) and ball-milling treatment for 1 h. NMR spectroscopy and gel-permeation chromatography of the glucan products showed a significant reduction in the degree of polymerisation (DP) and molecular weights (Mw). All prepared glucans improved gut stress evaluated by in vitro digestion and fermentation (young and aging mouse faecal inocula). C1.00 with lower DP and Mw showed better water solubility, earlier peak, and exhibited increased 1-diphenyl-2-picrylhydrazyl activity, higher ratios of Lactobacillus to Escherichia coli, and a higher level of short chain fatty acids better than C0.25 and C0.50 treatment (P < 0.05). Better prebiotic effects were observed in aging mice than in young mice. The highest ratio of Lactobacillus to E. coli was a 2.13-fold increase for aging mice compared to a 1.79-fold increase for young mice, relative to the initial value after C1.00 treatment. The study provides a novel pathway and a new resource for producing glucan.

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