Synthesis, Structural Elucidation, and Anti-Inflammatory Activity of a Water-Soluble Derivative of Arctiin

The poor oral bioavailability of arctiin caused by its low water solubility is the biggest obstacle in developing it as a drug. In this work, a new water-soluble glucuronide derivative of arctiin (arctigenin-4'-O-glucuronide) was synthesized through 2,2,6,6-tetramethylpiperidine 1-oxyl mediated oxidation reaction. Subsequently, its anti-inflammatory effect was evaluated by mice acute lung injury model in vivo. The results showed that the glucuronide derivative of arctiin not only had better water solubility but also displayed improved anti-inflammatory activity in vivo, thus serving as an innovative compound in the drug development of arctiin.

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.