Misc

Flavonoids are important bioactive compounds. To find new bioactive chromones and flavonoids, an efficient synthesis method that can add structural or substitutional diversity to molecules is important. We developed efficient one-pot synthesis of new chromone or flavonoid derivatives bearing heterocycle units by Michal-aldol reaction. To introduce additional diversity points on the molecules, Suzuki-Miyaura and Sonogashira-Hagihara coupling were performed. We also examined these reactions in solid-phase, and finally established a diverse molecule library with the naturally occurring scaffolds chromone and flavone by split & pool synthesis. The synthesized compounds are evaluated their inhibition of Hes1 promoter activities, which is one of the transcriptional factors in neural stem cells. As the result, we achieved to establish heterocyclic flavonoid or chromone library consisted of 561 compounds. Of them, we succeeded in finding 6 inhibitors of Hes1 promoter activity.

Basic helix-loop-helix (bHLH) repressor- and activator-type transcription factors play essential roles in proliferation and differentiation of neural stem cells (NSCs). Hes1, one of bHLH repressor-type factors, suppresses transcriptions of bHLH activator-type factors such as Mash1 by binding to their promoter regions as homodimers, which leads NSCs to remaining undifferentiation. Therefore, inhibition of Hes1 dimer formation would accelerate NSCs differentiation into neurons and glial cells. To quickly find ligands of bHLH factors from natural products extracts, we constructed Hes1 immobilized sepharose beads-HPLC method. Flavonoid glycosides (1-3), xanthone derivative (4) and polyene macrololactam (5) were isolated rapidly by this method.Compound 1 disrupted Hes1 dimer formation in mouse embryo fibroblast cells (C3H10T1/2), and moreover, 1 suppressed Hes1-mediated repression of bHLH activator-type transcription factor dose-dependently (reporter assay). In differentiation of mouse neural stem cells (MEB5), neurite outgrowth enhancement by 1 was clearly observed. The expression of pro-neural genes (activator-type bHLH transcription genes) such as Mash1 and NeuroD were increased by treatment of MEB5 with 1compared with those of control. These results suggested that the inhibition of Hes1 dimer formation by 1 would greatly contribute its mode-of-action. Compound 4 inhibited Hes1-mediated suppression of gene expression in reporter assay, although Hes1 dimer inhibition was not detected. The mechanism of 4 would be different with that of 1.

We are interested in a diverse compound library based on diversity oriented synthesis and searching for useful small molecules. Blebbistatin accelerates extension of axonal growth. We planned to synthesize various Blebbistatin derivatives with plural anthranilic acid units and pyrrolidone units for improvement of chemical properties and bioactivity of Blebbistatin. Four derivatives were synthesized in solution phase. Moreover, solid-phase synthesis was examined to obtain a lot of number of derivatives. For the solid phase library synthesis, pyrrolidone unit was attached to Merrifield resin. Solid-phase arylation of amide was examined by using arylboronic acid and Cu(OAc)2.

Rocaglamide derivatives, which are one of the cyclopenta[b]benzofuran compounds including in plants of Asian and Western Pacific region, are counted on bioactivities. We isolated two rocaglamide derivatives from leaves of Amoora cucullata (Meliaceae). They showed very strong activity in sensitizing to TRAIL, which leads to apoptosis of cancer cells. In this research, we aim to synthesize rocaglamide derivatives with heterocyclic units to discover their extraordinary potential. As first, we succeed the efficient synthesis of 2-furanyl-3-hydroxy-chromone. A phtochemical [3+2]-cycloaddition between the furanylchromone and methyl cinnamate smoothly proceeded. Base-induced rearrangement and reduction gave a 3a-furanyl-rocaglamide derivative in 6 steps 11% yield.