Acarbose May Function as a Competitive Exclusion Agent for the Producing Bacteria

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.

Acarbose glycosylation by AcbE for the production of acarstatins with enhanced α-amylase inhibitory activity

Acarbose is a potent glycosidase inhibitor widely used in the clinical treatment of type 2 diabetes mellitus (T2DM). Various acarbose analogs have been identified while exploring compounds with improved pharmacological properties. In this study, we found that AcbE from Actinoplanes sp. SE50/110 catalyzes the production of acarbose analogs that exhibit significantly improved inhibitory activity towards α-amylase than acarbose. Recombinant AcbE mainly catalyzed the formation of two new compounds, namely acarstatins A and B, using acarbose as substrate. Using high-resolution mass spectrometry, nuclear magnetic resonance, and glycosidase hydrolysis, we elucidated their chemical structures as O-α-d-maltosyl-(1 → 4)-acarbose and O-α-d-maltotriosyl-(1 → 4)-acarbose, respectively. Acarstatins A and B exhibited 1584- and 1478-fold greater inhibitory activity towards human salivary α-amylase than acarbose. Furthermore, both acarstatins A and B exhibited complete resistance to microbiome-derived acarbose kinase 1-mediated phosphorylation and partial resistance to acarbose-preferred glucosidase-mediated hydrolysis. Therefore, acarstatins A and B have great potential as candidate therapeutic agents for T2DM.

In Vitro Antioxidant and Enzyme Inhibitory Activities of Walnut Male Flowers

Walnut (Juglans regia L.) male flowers are known for their high phenolic content and associated health benefits, including anti-hypoxic, antihaemolytic, anti-inflammatory, antidepressant, and antioxidant activities. This study represents the first investigation of the inhibitory effects of walnut male flower extract on α-amylase and α-glucosidase enzymes, employing HPAE-PAD (High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection). The inhibitory potential of the extract was compared to that of acarbose, a chemical drug commonly used for this purpose. Furthermore, the antioxidant activity of the extract was also evaluated. The extract demonstrated significant inhibition of α-amylase and α-glucosidase, with half maximal inhibitory concentration (IC50) values of 1.507 mg/mL and 0.803 mg/mL, respectively. In contrast, acarbose exhibited IC50 values of 1.031 mg/mL and 0.985 mg/mL for α-amylase and α-glucosidase, respectively. Although the walnut male flower showed greater inhibition of α-glucosidase than acarbose, acarbose exhibited stronger inhibition of α-amylase activity than walnut male flowers. The extract exhibited a DPPH (1,1-Diphenyl-2-picrylhydrazyl radical) free radical scavenging activity, with an IC50 value of 19.51 µg/mL. Additionally, the total phenolic content of 277 mg GAE (gallic acid equivalent)/g dry weight (dw) was determined in the extract. These results may highlight the potential of walnut male flowers as a novel enzyme inhibitor for managing type 2 diabetes mellitus. The findings of this study could provide valuable insights for further investigation into the potential applications of walnut male flowers in the food and pharmaceutical industries.