Investigation of the preparation, characterization, and whitening activity of co-amorphous glabridin and oxymatrine

Glabridin (Gla) is a natural active ingredient extracted from licorice root with good whitening activity. However, its poor solubility limits its further application. Therefore, this study aimed to develop a novel co-amorphous Gla-OMT raw material using oxymatrine (OMT) as a co-former, aiming to improve its physicochemical properties and enhance its whitening activity. Firstly, the formation of co-amorphous Gla-OMT was confirmed by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). Subsequently, FT-IR, NMR, and molecular dynamics simulations were used to investigate the interaction between the co-amorphous Gla-OMT molecules, and solubility experiments and supersaturation dissolution experiments were used to investigate the solubilization of the co-amorphous Gla-OMT. In addition, the in vitro release mechanism of the co-amorphous Gla-OMT was investigated using a Franz diffusion cell and its biosafety and whitening activity were evaluated using cell experiments. In conclusion, the successful preparation of co-amorphous Gla-OMT and the evaluation of its whitening activity in this study have significant implications for guiding the development and application of whitening products in the future. This study successfully prepared co-amorphous Gla-OMT with good stability and whitening activity, which provides a theoretical and experimental basis for the development and application of related whitening products.