Cocrystallisation of Daidzein with Pyridine-derived Molecules: Screening, Structure Determination and Characterisation

Abstract Daidzein (7,4’-dihydroxyisoflavone, DAI) is an isoflavone found in soybeans and Pueraria. DAI has potential therapeutic benefits on cancer and osteoporosis yet has quite low solubility, limiting its use. Herein a cocrystal screening of DAI with pyridine-derived molecules, i.e., nicotinamide, isonicotinamide, caffeine, D-Proline, L-Proline and 4,4’-Bipyridine was conducted. A new cocrystal of Daidzein and 4,4’-Bipyridine (DAI-BIP) was successfully generated via grinding and solvent methods. DAI-BIP showed an increased solubility and dissolution rate. In comparison to DAI, there was a 2.03-fold increase of the dissolution performance parameter for DAI-BIP where the concentration observed for DAI quickly reached the equilibrium solubility and continued to reach 1.49 times DAI solubility. A parachute effect was also observed during the dissolution of DAI-BIP, indicating that BIP might be able to maintain the supersaturated state of DAI in solution proving DAI's ability to form cocrystals of higher solubility and enhanced dissolution properties through co-crystallisation.