Non-porphyrin photosensitizers in biomedicine

Conventional drugs used in the photodynamic therapy of cancer (PDT) are porphyrins or porphyrin congeners such as chlorins, phthalocyanines etc. Natural and synthetic alternatives to porphyrins are available which exhibit improved photoactivity in terms of singlet oxygen quantum efficiency, increased maximum wavelength and intensity of absorption. In addition, differences in structure and/or electronic charge can lead to intracellular tumour localisation and sites of action such as mitochondria, lysosomes etc., rather than destruction of tumour vasculature. Non-porphyrin antibacterials and antivirals are also under development.