Astragalosidic Acid: A New Water-Soluble Derivative of Astragaloside IV Prepared Using Remarkably Simple TEMPO-Mediated Oxidation

There is an urgent need for a water-soluble derivative of astragaloside IV for drug R&D. In the present study, a remarkably simple method for the preparation of such a water-soluble derivative of astragaloside IV has been developed. This protocol involves oxidative 2,2,6,6-tetramethylpiperidine-1-oxyl free radical (TEMPO)-mediated transformation of astragaloside IV to its carboxylic acid derivative, which is a new compound named astragalosidic acid. The structure of astragalosidic acid was elucidated by means of spectroscopic analysis. Its cardioprotective activity was investigated using an in vitro model of cardiomyocyte damage induced by hypoxia/reoxygenation in H9c2 cells. The oxidative TEMPO-mediated transformation proposed in the present study could be applied to other natural saponins, offering an effective and convenient way to develop a new compound with greatly improved structure-based druggability.