Takashi HIRANO (平野 誉)

To develop novel drugs for treating T-cell acute lymphoblastic leukemia (T-ALL) and acute myeloid leukemia (AML) which are highly malignant hematological tumors, a series of analogs having a polyenylpyrrole structure of natural compounds (rumbrin and auxarconjugatin B) were synthesized and investigated their structure–activity relationships (SAR) of in vitro anti-T-ALL and anti-AML activities. We obtained three findings: (1) introduction of a methyl group at the conjugated polyene terminus enhanced anti-T-ALL activity, (2) analogs with a 3-chloropyrrole moiety had even higher selectivity for T-ALL cells, and (3) some analogs were effective against AML-derived cells. Among the studied compounds, 3-chloro-2-(8-ethoxycarbonylnona-1,3,5,7-tetraenyl) pyrrole 4e was the most promising candidate of T-ALL- and AML-treating drug. This study provides useful structural information for designing novel drugs treating T-ALL and AML.

Heating crystal samples of 9,10-diphenylanthracene endoperoxide (1) and its deuterated derivative (1-d10) to 200 °C led to singlet-oxygen chemiluminescence (CL) from the mixtures of the crystalline and molten states. To understand the events in the heated samples, the reactions of 1 and 1-d10 in crystals were investigated by powder X-ray diffraction measurements and thermal analyses. The used crystals of 1 and 1-d10 obtained from a mixture of ethyl acetate (EA) and n-hexane contained EA. Other crystals of 1 obtained by slow recrystallization with the same solvents had a solvent-free structure (form II) different from the reported one (form I). The results confirmed that the EA-containing crystals of 1 and 1-d10 were transformed to form II in two steps at 40–50 and 60–75 °C under heating at elevated temperature. Thus, the crystal samples had the form-II structure soon after heating to 200 °C. The behavior of the heated samples indicates that the crystal lattice inhibits the thermal reactivity of 1. Thus, the temperature for initiating the thermolytic reaction of 1 becomes higher than the melting point. An exploration of the potential energy surface (PES) obtained by density functional theory (DFT) calculations also supports that the deoxygenation of 1 is prevented by retaining the anthracene framework in the crystalline state. This study indicates that the method to use a CL-active compound is a powerful tool to analyze the reaction behavior in the crystalline state.

A unique combinatorial bioluminescence (BL) imaging system was developed for determining molecular events in mammalian cells with various colors and BL intensity patterns. This imaging system consists of one or multiple reporter luciferases and a series of novel coelenterazine (CTZ) analogues named “S-series”. For this study, ten kinds of novel S-series CTZ analogues were synthesized and characterized concerning the BL intensities, spectra, colors, and specificity of various marine luciferases. The characterization revealed that the S-series CTZ analogues luminesce with blue-to-orange-colored BL spectra with marine luciferases, where the most red-shifted BL spectrum peaked at 583 nm. The colors completed a visible light color palette with those of our precedent C-series CTZ analogues. The synthesized substrates S1, S5, S6, and S7 were found to have a unique specificity with marine luciferases, such as R86SG, NanoLuc (shortly, NLuc), and ALuc16. They collectively showed unique BL intensity patterns to identify the marine luciferases together with colors. The marine luciferases, R86SG, NLuc, and ALuc16, were multiplexed into multi-reporter systems, the signals of which were quantitatively unmixed with the specific substrates. When the utility was applied to a single-chain molecular strain probe, the imaging system simultaneously reported three different optical indexes for a ligand, i.e., unique BL intensity and color patterns for identifying the reporters, together with the ligand-specific fold intensities in mammalian cells. This study directs a new combinatorial BL imaging system to specific image molecular events in mammalian cells with multiple optical indexes.