Enhancement of anti-diabetic activity of pomelo peel by the fermentation of Aspergillus oryzae CGMCC23295: In vitro and in silico docking studies

Effectively Enhancing the Physiological Activity and Sensory Quality of Whole Calamondin Puree via Yeast Fermentation

To explore the feasibility of pure yeast fermentation in whole Calamondin puree (FWCP) for the utilization of the whole fruit, yeasts were isolated from naturally fermented Calamondin, and their fermentation characteristics were evaluated. The results indicated that all yeasts were able to ferment FWCP, reducing the sour taste by degrading citric acid, increasing the contents of nutrients (such as phenols and limonins) and volatile compounds, and enhancing the antioxidant activity and inhibition of α-glucosidase activity (p < 0.05). Among them, P. terricola QJJY1 and H. opuntiae QJJY14 exhibited stronger abilities to degrade organic acids, with P. terricola QJJY1 enhancing the antioxidant capacity by releasing phenolic compounds such as phloretin-3',5'-di-c-β-glucoside, vitexin-2″-O-rhamnoside, and isomargaritene. Moreover, H. opuntiae QJJY15 improved the contents of characteristic volatile compounds such as terpene hydrocarbons and higher alcohols. In total, 70 components were identified as differential metabolites based on their fold change in the metabolites, with 42 differential metabolites involved in 29 metabolic pathways across four strains. The main pathways related to phenol and flavor enrichment were flavonoid, flavone, and flavonol biosynthesis, monoterpenoid biosynthesis, and glyoxylate and dicarboxylate metabolism. Therefore, yeast fermentation is an effective method for utilizing whole Calamondin.

Effect of Genistein on Starch Digestion In Vitro and Its Mechanism of Action

The digestive properties of starch are crucial in determining postprandial glycaemic excursions. Genistein, an active phytoestrogen, has the potential to influence starch digestion rates. We investigated the way genistein affected the digestive properties of starch in vitro. We performed enzyme kinetics, fluorescence spectroscopy, molecular docking, and molecular dynamics (MD) simulations for analysing the inhibitory properties of genistein on starch digestive enzymes as well as clarifying relevant mechanism of action. Our findings demonstrated that, following the addition of 10% genistein, the contents of slowly digestible and resistant starches increased by 30.34% and 7.18%, respectively. Genistein inhibited α-amylase and α-glucosidase, with half maximal inhibitory concentrations of 0.69 ± 0.06 and 0.11 ± 0.04 mg/mL, respectively. Genistein exhibits a reversible and non-competitive inhibiting effect on α-amylase, while its inhibition on α-glucosidase is a reversible mixed manner type. Fluorescence spectroscopy indicated that the presence of genistein caused declining fluorescence intensity of the two digestive enzymes. Molecular docking and MD simulations showed that genistein binds spontaneously to α-amylase via hydrogen bonds, hydrophobic interactions, and π-stacking, whereas it binds with α-glucosidase via hydrogen bonds and hydrophobic interactions. These findings suggest the potential for developing genistein as a pharmacologic agent for regulating glycaemic excursions.

Synchronous reducing anti-nutritional factors and enhancing biological activity of soybean by the fermentation of edible fungus Auricularia auricula

Auricularia auricula fermentation was performed to reduce anti-nutritional factors, improve nutritional components, and enhance biological activity of soybean. Results showed that the contents of raffinose, stachyose, and trypsin inhibitor were significantly decreased from initial 1.65 g L-1, 1.60 g L-1, and 284.67 μg g-1 to 0.14 g L-1, 0.35 g L-1, and 4.52 μg g-1 after 144 h of fermentation, respectively. Simultaneously, the contents of polysaccharide, total phenolics, and total flavonoids were increased, and melanin was secreted. The isoflavone glycosides were converted to their aglycones, and the contents of glyctin and genistin were decreased from initial 1107.99 μg g-1 and 2852.26 μg g-1 to non-detection after 72 h of fermentation, respectively. After 96 h of fermentation, the IC50 values of samples against DPPH and ABTS radicals scavenging were decreased from 17.61 mg mL-1 and 3.43 mg mL-1 to 4.63 mg mL-1 and 0.89 mg mL-1, and those of samples inhibiting α-glucosidase and angiotensin I-converting enzyme were decreased from 53.89 mg mL-1 and 11.27 mg mL-1 to 18.24 mg mL-1 and 6.78 mg mL-1, respectively, indicating the significant increase in these bioactivities. These results suggested A. auricula fermentation can enhance the nutritional quality and biological activity of soybean, and the fermented soybean products have the potential to be processed into health foods/food additives.