Porphyrins and cancer therapy

HpO (Stage II) mixure of monomeric eind dimers and oligomers 

The righthand side of the figure shows postulated Interporphyrin linkages 

HpD has been used to treat a variety of tumours and bladder cancers, breast cancers, and certain ocular cancers. Just as bilirubin photosensitises the production of singlet oxygen to bring about its own destruction in the photodynamic treatment of neonatal hyperbilirubinaemia (see Chapter 6), so components of HpD also produce singlet oxygen. And because the HpD tends to localise in tumour cells, so photosensitisation leads to then-destruction. 

It must be a pure compound with a reproducible synthesis. 

It must be activated at wavelengths 650 nm to ensure better absorption of tissue-penetrating red light, and so sensitisation by an external light source. 

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