title: Chelation with metal is not essential for antitumor photodynamic activity of sulfonated phthalocyanines.
abstract: It is generally assumed that a central metal is essential for the efficiency of phthalocyanines in photodynamic therapy (PDT) of cancer. Contrary to the set opinion, the results of the present study indicate that the metal-free sulfonated phthalocyanines (H2PcSn, where n is the number of sulfonate groups per molecule) possess a considerable photoactivity. The relative phototoxicities of H2PcS1.5, H2PcS2.4, H2PcS3.1 and H2PcS3.8 on HEp2 human epidermoid carcinoma cells were 3.3, 20, 3.3 and 1, respectively, thus demonstrating dependence of the activity on the sulfonation degree, known for metallo-PcSn. A significant delay in tumor growth and a decrease in tumor regrowth rate were observed in mice after PDT with H2PcS2.4. The antitumor effect declined in the order H2PcS2.4 > H2PcS3.1 > H2PcS1.5 and vanished for H2PcS3.8. We demonstrate here that the high photodynamic activity of H2PcS2.4 can be explained by its physicochemical properties in living cells and tissues. Thus, H2PcSn (n is about 2) can be considered as a new alternative in PDT of light-accessible neoplasms and further clinic-oriented studies are warranted.
authors.affiliation: Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow. alexei@nmr.ru
authors.forename: Alexei
authors.initials: A
authors.lastname: Feofanov
authors.forename: Alexei
authors.initials: A
authors.lastname: Grichine
authors.forename: Tatyana
authors.initials: T
authors.lastname: Karmakova
authors.forename: Natalia
authors.initials: N
authors.lastname: Kazachkina
authors.forename: Elena
authors.initials: E
authors.lastname: Pecherskih
authors.forename: Raisa
authors.initials: R
authors.lastname: Yakubovskaya
authors.forename: Eugene
authors.initials: E
authors.lastname: Luk'yanets
authors.forename: Valentina
authors.initials: V
authors.lastname: Derkacheva
authors.forename: Marguerite
authors.initials: M
authors.lastname: Egret-Charlier
authors.forename: Paul
authors.initials: P
authors.lastname: Vigny
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity*; D002455:Cell Division / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000633:toxicity*; D054833:Isoindoles; D008223:Lymphoma; D008670:Metals / Q000633:toxicity*; D010778:Photochemotherapy; D011838:Radiation-Sensitizing Agents / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D007211:Indoles; D054833:Isoindoles; D008670:Metals; D011838:Radiation-Sensitizing Agents; D017382:Reactive Oxygen Species; C013647:phthalocyanine