Abstracts

We have developed near-infrared (NIR) luciferin analogues that exhibit firefly bioluminescence, including compounds dubbed “TokeOni” and “seMpai,” which are now commercially available. In this conference, I will present the characteristics of NIR luciferin analogues.Firefly bioluminescence, a process whereby light is emitted with high efficiency, has found widespread use in life science applications. Notably, NIR light is suitable for use in in vivo imaging because deep tissues are highly permeable to light in the relevant wavelength range (650–900 nm). However, the wavelength of light emitted via firefly bioluminescence is usually yellow–green (560 nm). We performed studies on the structure–activity relationship of compounds producing firefly bioluminescence in order to synthesize luciferin analogues emitting NIR light. Thus, AkaLumine, a luciferin analogue that produces light at 675 nm wavelength, was developed. This compound was shown to yield useful results when applied to the in vivo imaging of mice. We have improved the characteristics of AkaLumine to optimize this compound for use in in vivo imaging, thus obtaining the compounds dubbed TokeOni and seMpai. Recently, Akaluc, an artificial enzyme that specifically catalyzes the light-producing oxidation of TokeOni, has been developed. As a result, it became possible to in vivo imaging for larger animals than mice like micro pig and marmoset. In this way, bioluminescence imaging technology is undergoing constant innovation, and we continue to develop NIR luciferin analogues that can be used as imaging tools. In the present study, we aimed to develop bioluminescent systems emitting light at wavelengths over 700 nm; we thus synthesized luciferin analogues and evaluated their bioluminescence light.In this conference, I will present the characteristics of recently developed NIR luciferin analogues including the synthesized luciferin analogs showed over 750 nm emission of light “GeKiaka” and “KinPachi”.