The present invention relates to a composite for the treatment of a variety of medical conditions, the composite comprising an oxidized gluthathione-based compound, which has a disulfide bond, and a metal material, in particular where the metal is either platinum or palladium. The oxidized glutathione-based compound and metal material can be present in a ratio of 3000 to 1 and preferably 1000 to 1. The oxidized glutathione-based compound can be oxidized glutathione itself or salts or derivatives. A feature of the invention is that the composite has a more stabilized disulfide bond than the oxidized glutathione-based compound itself. Methods for preparing the composite are provided, such methods being beneficial in that the composite is provided in high yields and at high purity. Methods for treating various medical conditions with the composites of the present invention are also disclosed.