pH-Responsive Fluorescent Switches through Intramolecular Conjugate Addition Reactions and Application in Fluorogenic Bioimaging.

We report new photoluminescent switching systems achieved through pH-induced intramolecular oxa-Michael conjugate addition reactions. Ratiometric absorbance and fluorescence emission were observed across conjugate acceptors triggered by pH, resulting in specific pseudo p values. The effect of substituents on the pseudo p's was investigated, showing increased values from electron-withdrawing to electron-donating groups.

Soluble dietary fibres decrease α-glucosidase inhibition of epigallocatechin gallate through affecting polyphenol-enzyme binding interactions.

The effects of soluble dietary fibres (SDFs) on α-glucosidase inhibition of EGCG were studied. Three arabinoxylans and polygalacturonic acid (PGA) significantly decreased inhibitory activity of EGCG against α-glucosidase, while two β-glucans hardly affected the inhibition. Although arabinoxylans and PGA weakened the competitive inhibition character of EGCG, they maintained the fluorescence quenching effect of EGCG.