CPO and cancer: Zaks and Dodds investigated thesubstrate specificity of CPO in a series of oxidation reactions anddemonstrated that straight-chain aliphatic and cyclic cis-olefinscould undergo epoxidation in a highly stereoselective manner, whilealiphatic and aromatic alcohols were oxidized to their correspondingaldehydes and acids.8 The oxidation ofindole is of interest as oxygenated indole derivatives are used inthe treatment of several diseases including cancer, diabetes, andviral infections.14 In the presence ofchloroperoxidase (CPO), indole is oxidized by H2O2 to 2-oxindole as the main product.