Fluorescent probes for imaging formaldehyde in biological systems

Abstract

Formaldehyde (FA) is a common environmental toxin but is also endogenously produced through a diverse array of essential biological processes, including mitochondrial one-carbon metabolism, metabolite oxidation, and nuclear epigenetic modifications. Its high electrophilicity enables reactivity with a wide variety of biological nucleophiles, which can be beneficial or detrimental to cellular function depending on the context. New methods that enable detection of FA in living systems can help disentangle the signal/stress dichotomy of this simplest reactive carbonyl species (RCS), and fluorescent probes for FA with high selectivity and sensitivity have emerged as promising chemical tools in this regard.

Figure 1

(a) Selected enzymatic pathways that generate FA in biological systems. (b) Subcellular localization of FA-generating enzymes. Abbreviations: α-KG, α-ketoglutarate; KDM, lysine demethylase; ALKBH, AlkB homologues; SSAO, semicarbazide-sensitive amine oxidases; DMGDH, dimethylglycine dehydrogenase; SARDH, sarcosine dehydrogenase; FTO, fat mass and obesity-associated protein.

Figure 2

Molecular probes for the detection of FA. Three general detection strategies have been taken: 2-aza-Cope-based, formimine-based, and aminal-based. Coloring reflects excitation wavelengths.