Influence of cationic, anionic or non-charged substituents on photodynamic activity of water-soluble zinc (aza)phthalocyanines

Solubility of (aza)phthalocyanines ((Aza)Pc) in water is very limited due to their flat aromatic core that makes them prone to aggregation. Stacking of (Aza)Pc cores (forming dimers or higher-order aggregates) leads to quenching of their excited states – fluorescence and 1O2 production [1]. Several approaches to improve the solubility have been described, but truly non aggregating water-soluble (Aza)Pcs are still scarce [2-7]. Here we present a series of novel water-soluble hydrophilic and amphiphilic zinc (Aza)Pcs with differently charged (cationic and anionic) as well as non-charged peripheral substituents. These compounds were directly compared to several clinically approved photosensitizers (PSs; verteporfin, temoporfin, Photosens, methylene blue and protoporphyrin IX – a photodynamically active product of a prodrug 5-aminolevulinic acid).