Research progress on co-crystal of insoluble active ingredients of Chinese materia medica / 中草药

ABSTRACT

Co-crystal is a crystalline structure composed of at least two components, where the components may be active pharmaceutical ingredients (APIs) and co-formers in stoichiometric amounts. Co-crystal structure exhibits long range order and the components interact via non-covalent interaction such as hydrogen bonding, ionic interaction, vander-waals interaction, and π-π interaction. The intermolecular interaction and resulting crystal structure can generate physicochemical properties which differ from the properties of the individual components. Such properties include melting point, solubility, chemical stability, and mechanical properties. Meanwhile, co-crystal can break through patents protection of APIs. So co-crystal attracts more attention in pharmaceutical research and development field. With the development of pharmaceutical co-crystals, there may be an opportunity for improving the insoluble active ingredients of Chinese materia medica (CMM) in further development. This review has been organized around four categories the co-crystals of flavonoids (I), alkaloids (II), terpenes (III), and polyphenols (IV) and their effects on physicochemical properties and bioavailability of those APIs, which provide a good reference for the application of pharmaceutical co-crystals in insoluble active ingredients of CMM.