3-Hydroxykynurenic acid: Physicochemical properties and fluorescence labeling. (March 2019)

• Record Type: Journal Article
• Authors: Shmidt, María S.; García Vior, María C.; Ezquerra Riega, Sergio D.; Lázaro-Martínez, Juan M.; Abasolo, María I.; Lazaro-Carrillo, Ana; Tabero, Andrea; Villanueva, Angeles; Moglioni, Albertina G.; Blanco, María M.; Stockert, Juan C.
• Is Part Of: Dyes and pigments. Volume 162(2019)
• Page Start: 552
• Page End: 561
• Publication Date: 2019-03
• Subjects: Fluorescent labeling -- Quinolinones -- Fluorophore -- Biocompatibility; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2018.10.027
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Quinoline is one of the most important heterocyclic systems in life sciences. Some derivatives are normal metabolites, and others are used as antibacterial, antimalarial, and anticancer agents. In this work, we describe the synthesis, physicochemical properties, and fluorescence features of a new 4-quinolinone fluorophore, 3-hydroxykynurenic acid (3-HOKA). 3-HOKA was obtained by alkoxide-induced rearrangement of ethyl isatinacetate followed by acidification and then alkaline hydrolysis. The fluorescent compound was characterized by NMR, MS, IR, and UV–Vis spectra. 3-HOKA can exist under a keto-enol equilibrium, but the 4-quinolinone form is the predominant tautomer. In PBS (pH = 7.4), the anionic keto form of 3-HOKA showed a maximum absorption at 368 nm, a fluorescence peak at 474 nm, and a fluorescence quantum yield (ΦF ): 0.73. 3-HOKA is photostable and is a moderately weak oxygen generator. Viability assays on HeLa cells indicated that 3-HOKA did not induce significative cytotoxic effects. Under UV excitation, a bright blue fluorescence was selectively found in a singular body within the cytoplasm, a labeling pattern that suggests the possible localization of the probe in the centriole or related structures. Therefore, this novel fluorophore represents a promising prototype compound owing to its biocompatibility and potential biological applications. Highlights: Synthesis and physicochemical properties of a new 4-quinolinone fluorophore. Biocompatible fluorescent probes with application in cell imaging. Perinuclear or peripheral body with high blue fluorescence could be visualized.