New Chrysin-based co-crystals: Synthesis, characterization and dissolution studies

Chrysin (CHY), as an important flavonoid molecule, shows various pharmacological activities. However, the character of weak solubility in water restricts its pharmacology in human body. In order to further understand the interactions of OH⋯N between hydroxyl groups of chrysin and various aromatic amines,and to improve the dissolution of CHY, BPY(4,4′-bipyridine) and R1(1,4-bis(pyridin-4-ylmethoxy)benzene) were assembled with CHY to form two new co-crystals (HNU-65 and 66, HNU is the abbreviation of Hainan University). Structural analysis shows that HNU-65 and 66 are formed by hydrogen bonds and π-π interaction between CHY molecules with BPY/R1 molecules, respectively. Importantly, in phosphate buffer of pH=7.4, the solubility of these two co-crystals has improved greatly. Furthermore, the two co-crystals exhibited good biological suitability by cytotoxicity assays.