Fluorogenic 7-azidocoumarin and 3/4-azidophthalimide derivatives as indicators of reductase activity in microorganisms

Abstract

A series of fluorogenic heterocyclic azides were prepared and assessed as reductase substrates across a selection of Gram-negative and Gram-positive microorganisms. The majority of these azides showed similar activity profiles to nitroreductase substrates. Microorganisms that do not produce hydrogen sulfide reduced the azides, indicating reductase activity was not linked to hydrogen sulfide production.

A Highly Water-Soluble Fluorescent and Colorimetric pH Probe

“…On the other hand, fluorescence must be guaranteed by a suited emissive core. Heterocyclic molecules [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], as one of the most important classes of compounds, can play the role of fluorogenic moiety. At present, one of the major problems encountered in optimizing optical sensors is achieving the right balance between the presence of the fluorogenic unit (soluble in organic solvents) and the water solubility.…”

4-Azidocinnoline—Cinnoline-4-amine Pair as a New Fluorogenic and Fluorochromic Environment-Sensitive Probe

“…The conversion of azide 5 to amine 6 in a culture medium detected by fluorescent microscopy and FACS was proved by HPLC analysis of cell lysate. Considering that aromatic azides are known to be substrates for different enzymes (nitroreductases in microorganisms, [29] bactosomal CYP450 enzymes (CYP 1A2, 2D6, 3A4, 2C9, 2C19)), which are able to reduce aromatic azides to amines, and since aromatic azides can undergo H 2 S-mediated reduction under various conditions in in vitro and in vivo settings [48], the discovered azide−amine pair with a cinnoline core may find a range of biological applications, including intracellular reductase activity assays.…”

“…Taking into account the growing interest in a wide range of biological applications of fluorogenic azide/amine pairs [29,[31][32][33], we were interested in whether the discovered fluorogenic probe based on the 4-azidocinnoline/cinnolin-4-amine pair retains its fluorogenic properties in living cells.…”

“…In order to obtain fluorescent material from a non-fluorescent azide probe, the azido group can be modified in two ways: the conversion of azides into a 1,2,3-triazole derivatives by CuAAC [15,[18][19][20][21][22][23] or SPAAC [23,24] (Figure 1A) or the reduction of azides to amines [23][24][25][26][27][28][29] (Figure 1B). The formation of fluorescent 1,2,3-triazoles from non-fluorescent azides is widely applied in bioimaging [15,[18][19][20][21][22]30].…”

“…The reductive «azide to amine» transformation has been used for the detection of sulfide ions [25][26][27][28]31,32]. Moreover, it has been found that the azide group can be used as novel bioreductive functionality for the detection of intracellular hypoxia [33] and as a substrate for nitroreductases in microorganisms [29]. Recently, emissive in water quinoline-amines derived from corresponding azides as conjugates with peptides were discovered as probes for sensing the reactivity of protease K [34].…”