In this study, 12 flavonoid glycosides were selected based on virtual screening and the literature, and Quercimeritrin was selected as the best selective inhibitor of α-glucosidase through in vitro enzyme activity inhibition experiments. Its IC₅₀ value for α-glucosidase was 79.88 µM, and its IC₅₀ value for α-amylase >250 µM. As such, it could be used as a new selective inhibitor of α-glucosidase. The selective inhibition mechanism of Quercimeritrin on the two starch-digesting enzymes was further explored, and it was confirmed that Quercimeritrin had a strong binding affinity for α-glucosidase and occupied the binding pocket of α-glucosidase through non-covalent binding. Subsequently, animal experiments demonstrated that Quercimeritrin can effectively control postprandial blood glucose in vivo, with the same inhibitory effect as acarbose but without side effects. Our results, therefore, provide insights into how flavone aglycones can be used to effectively control the rate of digestion to improve postprandial blood glucose levels.

We investigated the effect of extraction temperature on the gel properties of gelatin from the skin of the American bullfrog (Rana catesbeiana) and the mechanisms. The textural and rheological properties of bullfrog gelatin extracted at 45 °C (G45), 55 °C (G55), and 65 °C (G65) were measured. The molecular weight distributions, microstructures, and amino acid compositions of the bullfrog gelatins were also determined. G45, G55, and G65 had gel strengths of 272.1, 225.6, and 205.8 g and hardness values of 28.1, 24.0, and 22.5 N, respectively. The gelling temperatures ranged from 19.3 to 23.9 °C, and the melting temperatures ranged from 28.9 to 31.5 °C. All the results were compared with those of commercial porcine gelatin. We propose that the higher gel strength of G45 with a higher band intensity of α2-chains compared with G55 and G65 was more likely to form ordered and strong cross-links. The gelatin extracted at a lower temperature (G45) had a finer gel structure, suggesting that it would be more difficult to disrupt by applied force. Gelatin extracted at a lower temperature demonstrated better properties with α2-chains and a fine gel structure. These results provide basic information on the extraction of American bullfrog skin gelatin for industrial applications.

Ensuring the stability of zein nanoparticles at different pH levels is crucial for their application as nanocarriers. In this study, octenyl succinic anhydride-modified starch (OSA-modified starch) was employed to enhance the stability of zein nanoparticles against different pH levels by forming complex nanoparticles with OSA-modified starch. The effect of preparation pH on the stability of the zein/OSA-modified starch nanoparticles was investigated. Sedimentation occurred in zein nanoparticles as the pH reached the isoelectric point. However, the stability of zein nanoparticles at various pH levels significantly improved after adding OSA-modified starch to form zein/OSA-modified starch nanoparticles regardless of whether they were prepared under acidic or alkaline pH conditions. Notably, the stability of zein/OSA-modified starch nanoparticles prepared at an acidic pH was higher than that of those prepared at an alkaline pH, thereby highlighting the critical role of the preparation pH for zein/OSA-modified starch in maintaining the stability of zein. The stable zein/OSA-modified starch nanoparticles developed in this study exhibit significant potential for use in delivery systems across various pH environments.