New Chemodosimetric Reagents as Ratiometric Probes for Cysteine and Homocysteine and Possible Detection in Living Cells and in Blood Plasma

Abstract

In this work, we have rationally designed and synthesized two new reagents (L(1) and L(2)), each bearing a pendant aldehyde functionality. This aldehyde group can take part in cyclization reactions with β- or γ-amino thiols to yield the corresponding thiazolidine and thiazinane derivatives, respectively. The intramolecular charge-transfer (ICT) bands of these thiazolidine and thiazinane derivatives are distinctly different from those of the molecular probes (L(1) and L(2)). Such changes could serve as a potential platform for using L(1) and L(2) as new colorimetric/fluorogenic as well as ratiometric sensors for cysteine (Cys) and homocysteine (Hcy) under physiological conditions. Both reagents proved to be specific towards Cys and Hcy even in the presence of various amino acids, glucose, and DNA. Importantly, these two chemodosimetric reagents could be used for the quantitative detection of Cys present in blood plasma by using a pre-column HPLC technique. Such examples are not common in contemporary literature. MTT assay studies have revealed that these probes have low cytotoxicity. Confocal laser scanning micrographs of cells demonstrated that these probes could penetrate cell membranes and could be used to detect intracellular Cys/Hcy present within living cells. Thus, the results presented in this article not only demonstrate the efficiency and specificity of two ratiometric chemodosimeter molecules for the quantitative detection of Cys and Hcy, but also provide a strategy for developing reagents for analysis of these vital amino acids in biological samples.

Design strategies of fluorescent probes for selective detection among biothiols

“…9), and it became the most frequently used reaction type for differentiating Cys/Hcy from GSH. [33][34][35][36][37][38] It was exploited by the Strongin group in 2004 to create the first example of a probe (11) for the selective detection of Cys/Hcy over GSH (Fig. 10).…”

Dual‐Emission Channels for Simultaneous Sensing of Cysteine and Homocysteine in Living Cells

“…In the past few years, various fluorescence probes specific for Cys, Hcy, and GSH on the basis of different mechanisms, including nucleophilic substitution, Michael addition, cyclization reactions with aldehydes, cleavage reactions by thiols, and others, were exploited. Recently, a single probe that could differentiate simultaneously between Cys/Hcy and GSH was reported.…”

A highly selective and sensitive ON–OFF–ON fluorescence chemosensor for cysteine detection in endoplasmic reticulum

“…As a well-known thiol-containing amino acid in this family, Cys serves as the building block in protein synthesis, detoxification, and metabolism in live organisms Chen et al, 2013;Chen et al 2013;Li et al, 2009;Das et al, 2012). Alterations in the level of cellular Cys has been implicated with neurotoxicity, and the deficiency of Cys may lead to many syndromes, such as a hematopoiesis decrease, slow growth, hair depigmentation, leucocyte loss, psoriasis and so on (Shiu et al, 2011;Yin et al, 2013;Shao et al, 2011;Zhou et al, 2013;Wang et al, 2014).…”