The objective of this review is to summarize knowledge on the inhibitory effects (IEs) of flavonoids on α-amylase (αA) and α-glucosidase (αG) relevant to the search of substitutes of acarbose (Aca). Flavonoids reported to be more effective at inhibiting αG than Aca have been summarized. The concept of “relative coefficient to Aca (RC_Aca)” has been proposed to integrate data from various reports. Correlations between hydrogen bond donors (H-donors), hydrogen bond acceptors (H-acceptors), partition coefficient values (XLog P3), and RC_Aca are discussed. Two kinds of binding modes between flavonoids and enzymes have been observed: (i) flavonoids directly bind to amino acid residues (AARs) in the active sites of enzymes and exclude the binding of substrate; (ii) flavonoids interact with AARs near the active site and close the channel to the active center. Some groups are correlated with stronger IEs: (i) substitutions of caffeoyl, galloyl, and prenyl groups in flavonoids enhance IEs; (ii) steric hindrance attenuates IEs, and linear molecules tend to be stronger inhibitors of porcine pancreatic αA (PPA). Whilst many achievements have been made, our understanding of the combined effects of different flavonoids, and flavonoids and Aca, remain ambiguous, and the effects of food matrices and stomach digestion on IEs of flavonoids are poorly understood. This review provides a comprehensive understanding on the use of flavonoids as αA and αG inhibitors for controlling diabetes.

Inflammatory bowel disease (IBD) is a chronic, multifactorial and inflammatory disease occurring in the colon tract. Bioactive polysaccharides from natural resources have attracted extensive attention due to their safety, accessibility and good bioactivities. In recent years, a variety of natural bioactive polysaccharides have been proven to possess anti-inflammatory effects on treating acute colitis. The objective of this review was to give an up-to-date review on the anti-inflammatory effects and mechanisms of natural polysaccharides on acute colitis. The anti-inflammatory effects of natural polysaccharides on acute colitis concerning clinical symptoms amelioration, colon tissue repairment, anti-oxidative stress alleviation, anti-inflammation, immune regulation, and gut microbiota modulation were comprehensively summarized. In addition, inducible murine models for assessing the anti-inflammatory effects of natural polysaccharides on acute colitis were also concluded. This review will offer the comprehensive understanding of anti-inflammatory mechanisms of natural polysaccharides in acute colitis, and render theoretical basis for the development and application of natural polysaccharides in drug and functional food.