An Aza-Cope Reactivity-Based Fluorescent Probe for Imaging Formaldehyde in Living Cells

Abstract

Formaldehyde (FA) is a reactive carbonyl species (RCS) produced in living systems that has been implicated in epigenetics as well as in the pathologies of various cancers, diabetes, and heart, liver, and neurodegenerative diseases. Traditional methods for biological FA detection rely on sample destruction and/or extensive processing, resulting in a loss of spatiotemporal information. To help address this technological gap, we present the design, synthesis, and biological evaluation of a fluorescent probe for live-cell FA imaging that relies on a FA-induced aza-Cope rearrangement. Formaldehyde probe-1 (FAP-1) is capable of detecting physiologically relevant concentrations of FA in aqueous buffer and in live cells with high selectivity over potentially competing biological analytes. Moreover, FAP-1 can visualize endogenous FA produced by lysine-specific demethylase 1 in a breast cancer cell model, presaging the potential utility of this chemical approach to probe RCS biology.

Mammals divert endogenous genotoxic formaldehyde into one-carbon metabolism

“…Formaldehyde was detected with FAP-1, a formaldehyde-specific fluorescent probe19. For the in vitro analysis, formaldehyde, THF or other folate derivatives were mixed with FAP-1 (10 μ M) in PBS (pH 7.4) in a 96-well plate.…”

“…2a). To test this hypothesis, we used a highly specific, cell-permeable fluorescent formaldehyde probe (FAP-1)19. Both formaldehyde and THF activated this probe in vitro in a concentration-dependent manner (Fig.…”

A 2-aza-Cope reactivity-based platform for ratiometric fluorescence imaging of formaldehyde in living cells

“…However, traditional methods for FA analysis in biological samples 17–22 typically involve extensive sample processing and/or destruction, leading to a loss of spatiotemporal resolution and an inability to follow FA fluxes in situ . Recent efforts by our laboratory 23 and others 24–33 have produced fluorescence-based probes for selective FA bioimaging using reactivity approaches, 34–37 based largely on either 2-aza-Cope rearrangement or formimine formation as an FA-responsive reaction. These reagents have been found useful for FA detection in living cells, 23–27 tissues, 28–31 and food samples.…”

A Reaction-Based Fluorescent Probe for Imaging of Formaldehyde in Living Cells

“…22 However, no such imaging agents were previously available for in cellulo imaging of FA. 23 We now present a new approach for the detection of FA in live cells through the development of Formaldehyde Probe 1 (FP1), a FAresponsive fluorescent indicator which is comprised of three discrete elements: a fluorescent core (Figure 1, in black), a FA reactive moiety (Figure 1, in blue), and a dark quencher ( Figure 1, in red). 24 A new julolidine-based silicon rhodol fluorescent scaffold was developed for the construction of FP1.…”