A colorimetric sensing platform for α-glucosidase activity monitoring and inhibitor screening via in situ reduction of 2,6-dichlorophenolindophenol

Abstract

As a membrane-bound enzyme, α-glucosidase (α-Glu) is closely associated with the pathogenesis of type 2 diabetes mellitus, making accurate monitoring of its enzymatic activity and screening of potential inhibitory compounds crucial for both clinical diagnostics and therapeutic development. Herein, we developed a colorimetric platform that synergistically integrates enzymatic catalysis with the redox-responsive optical characteristics of 2,6-dichlorophenolindophenol (DCIP). In this strategy, α-Glu enabled the removal of glucose from 2-O-α-D-glucopyranosyl-L-ascorbic acid to yield ascorbic acid, followed by in situ reduction of DCIP to reduced DCIP (_redDCIP). As a result, a dramatic color fading from blue to colorless and a substantial decrease of absorbance at 612 nm were both observed, which were used for both qualitative visual assessment and quantitative spectrophotometric analysis for α-Glu activity. The proposed mechanism was systematically validated through UV-vis spectroscopic characterization and electrospray ionization mass spectrometry analysis. Under optimized experimental conditions, the system demonstrated excellent analytical performance with a good linear response between the absorbance and α-Glu activity over a dynamic range of 2–70 U L⁻¹. The platform achieved a low detection limit of 0.68 U L⁻¹, fulfilling the sensitive monitoring of α-Glu activity. Notably, the proposed approach exhibited several advantages over conventional methods, including user-friendly operation, cost-effective instrumentation and rapid assay without the complex synthesis and modification of nanomaterials, and has been applied to the screening of α-Glu inhibitors obtained from natural plant extracts. Overall, the established sensing platform enables not only the sensitive detection of α-Glu activity but many also the screening of its inhibitor.