Discovery of alkene-conjugated luciferins for redshifted and improved bioluminescence imaging in vitro and in vivo .

The firefly luciferase system is the most extensively utilized bioluminescence system in the field of life science at the moment. In this work, we designed and synthesized a series of alkene-conjugated luciferins to develop new firefly bioluminescence substrates, and further evaluated their activities in vitro and in vivo . It is worth noting that the maximum biological emission wavelength of novel luciferin analogue AL3 (( S , E )-2-(6-hydroxy-5-(3-methoxy-3-oxoprop-1-en-1-yl)benzo[ d ]thiazol-2-yl)-4,5-dihydrothiazole-4-carboxylic acid) is 100 nm red-shifted compared with D-luciferin, while that of analogue AL4 (( S , E )-2-(5-(2-cyanovinyl)-6-hydroxybenzo[ d ]thiazol-2-yl)-4,5-dihydrothiazole-4-carboxylic acid) is 75 nm red-shifted. The new substrate AL2 (( S , E )-2-(6-hydroxy-7-(3-methoxy-3-oxoprop-1-en-1-yl)benzo[ d ]thiazol-2-yl)-4,5-dihydrothiazole-4-carboxylic acid) showed better bioluminescence performance in vivo .