Innovation of New Luciferin Analog for In Vivo Imaging

【Introduction】 We are innovating new imaging technologies by using organic chemistry. For making advanced medicinal technology, in vivo imaging is needed. So, we have been developing compounds suitable for deep in vivo imaging. 【Background】 It is very difficult for deep in vivo imaging to be absorbed and scattered light in living tissue. But, it is well known that the light in the near infrared region (NIR) has high permeability for the living tissue. It is a challenge to visualize in vivo deep imaging by developing an imaging material that has NIR emission. We have got structure-activity relationship data on the firefly luciferin luciferase reaction. According to the structure-activity relationship data on luciferin analogues, we have designed and marked NIR probe “Akalumine Ⓡ , (WAKO pure chemical LTD.). Akalumine Ⓡ gives a higher brightness compared with the natural firefly luciferin because of high permeability Akalumine Ⓡ in tissue. 【Purpose】 We try to rise concentration of the firefly luciferin for high dose. But we faced difficulty that Akalumine Ⓡ has low water-soluble. For various applications, “high dose” is key technology on in vivo imaging. Based on the Akalumine Ⓡ structure, new luciferin analogues have designed and synthesized three types. 【Result and conclusion】 We made the substances of three new luciferin analogues. One of these emits in the NIR and another has water-solubility increased by 15 fold for Akalumine Ⓡ . We will apply new probe to the animal for conforming practical ability and discuss these new luciferin analogues for in vivo imaging technology.