Luminescence of coelenterazine derivatives with C-8 extended electronic conjugation

Replacement of the methylene group at the C-8 position with an extended electronic conjugation is a new promising method to develop red-shifted coelenterazine derivatives. In this paper, we have described an oxygen-containing coelenterazine derivative with a significant red-shifted (63 nm) bioluminescence signal maximum relative to coelenterazine 400a (DeepBlueC^TM, 1). In cell imaging, the sulfur-containing coelenterazine derivative displayed a significantly (1.77±0.09; P≤0.01) higher luminescence signal compared to coelenterazine 400a and the oxygen-containing coelenterazine derivative exhibited a slightly (0.74±0.08; P≤0.05) lower luminescence signal. It is beneficial to understand further the underlying mechanisms of bioluminescence.