A revised version of the Iwaoka's assay: Application of hyphenated techniques

Assessing the effects of glutathione peroxidase (GPx)-like catalytic activities of natural, semi-synthetic, and synthetic compounds is nowadays well recognized of importance for the preliminary screening of potential anti-inflammatory, neuroprotective, and anti-cancer agents. To this aim the Iwaoka's assay, relying on ¹H NMR data recording, has been the most exploited test. In this short communication we propose an efficient and easy to perform methodology to accomplish the same process based on the application of hyphenated techniques like gas-chromatography coupled to mass spectrometry (GC-MS) and high-performance liquid chromatography with diode array detection (HPLC-DAD). The assay consisted in monitoring and quantifying the oxidation at different times of 1,4-dithiothreitol to 4,5-dihydroxy-1,2-dithiane in the presence of H₂O₂ and 2-phenyl-1,2-benzoselenazol-3(2H)-one (Ebselen) as the catalyst in EtOAc or MeOH as the solvents. The results we recorded by the application of both GC-MS and HPLC-DAD, showed that the GPx-like activity of Ebselen, used as the reference compound, can be effectively monitored in a time-course manner, and compare favorably to the NMR-based test.