Co-solubilisation of a binary mixture of isoflavones in a water micellar solution of sodium cholate or cetyltrimethylammonium bromide: Influence of micelle structure

Abstract

During co-solubilisation of a binary mixture of daizdein (D) and genistein (G) in a micelle water solution of sodium cholate (SC), G synergistically affects the solubilisation of D, while D antagonistically affects the solubilisation of G. In SC micellar binary mixtures of isoflavones, the interaction parameter (coefficient of activity) of molecule D is <1, while for G it is >1, i.e. D molecules are thermodynamically more stable than in the micellar pseudophase without G. It is assumed that formation of SC secondary micelles have a role in the thermodynamic stabilisation of D, especially when the content of the micellar binary mixture of isoflavones leads to a molar fraction of 1. In micellar co-solubilisation of the same binary mixtures with cetyltrimethylammonium bromide (CTAB), a mutual antagonistic effect occurs between components of the mixture related to their solubilisation. This is probably the result of competition between D and G for micelle binding sites.