ABSTRACT
Hypochlorite (HClO) is involved in various physiological and pathological processes as well as regulation of lysosomal functions. Thus, it is appreciated to develop efficient molecule tools for precisely detecting HClO in lysosomes. Although several lysosomal-targetable fluorogenic probes for HClO have been developed to date, they still suffered from the discounted sensing performance under lysosomal acidic condition. Herein, on the basis of the "AND" logic gate strategy, a novel dual-activatable fluorogenic probe CS has been rationally designed by simultaneously incorporating HClO recognition site and pH-sensitive group with lysosomal-targetable characteristic into a coumarin fluorophore. Different from the single-activated ones previously reported, CS exhibited good sensitivity, high specificity and fast response towards HClO under the acidic conditions but was out of operation in the neutral or alkaline environment. Importantly, it had been successfully applied for spatial-resolution imaging of exogenous or endogenous HClO in lysosomes.
Subject(s)
Coumarins/chemistry , Fluorescent Dyes/chemistry , Hypochlorous Acid/analysis , Lysosomes/metabolism , Coumarins/chemical synthesis , Coumarins/toxicity , Density Functional Theory , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/toxicity , HeLa Cells , Humans , Hydrogen-Ion Concentration , Limit of Detection , Microscopy, Confocal/methods , Microscopy, Fluorescence/methods , Models, Chemical , Spectrometry, Fluorescence/methodsABSTRACT
AIM: To evaluate the effect of paeonol on the activity of tyrosinase and provide experimental evidence for the treatment of hyperpigmentation disorders. METHODS: Tyrosinase activity was estimated by measuring the oxidation rate of L-3,4-dihydroxyphenylalanine (L-Dopa). The inhibitory effects of paeonol on the activity of mushroom tyrosinase and Michaelis-Menten kinetics were deduced from the Lineweaver-Burk plots. RESULTS: The inhibitory concentration of paeonol leading to 50% enzyme activity lost (IC50) was estimated to be 0.60 mmol x L(-1). The inhibition constants for paeonol binding free enzyme, K(I), and substrate-enzyme, K(IS), are 0.084 and 0.12 mmol x L(-1), respectively. CONCLUSION: Paeonol is a potential mixed inhibitor of mushroom tyrosinase. The mixed inhibition function may originate from its ability to form a Schiff base with a primary amino group and to chelate copper at the active site of tyrosinase.
