Biologically active compounds that can be used as photosensitizers for diagnostic and therapeutic applications, particularly for PDT of cancer, infections and other hyperproliferative diseases, fluorescence diagnosis and PDT treatment of a non-tumorous indication such as arthritis, inflammatory diseases, viral or bacterial infections, dermatological, ophthalmological or urological disorders are provided as well as providing methods to obtain them in pharmaceutical quality. In addition, conjugates are provided in which these photosensitizers are attached to water-soluble polymers via cleavable linkers that can be cleaved in the body under specific conditions. Another embodiment consists of formulating the desired tetrapyrrole photosensitizer into a pharmaceutical formulation to be injected into the body avoiding undesirable effects like solubility problems or delayed pharmacokinetics of the tetrapyrrole systems.
