| Description: |
Two series of luminescent cyclometalated Pt(II) com-plexes were synthesized a nd their biological activitywas assessed. One was based on the deprotonated do-nor-acceptor 2-(4-dimethylaminephenyl)benzothiazoleligand (NMe 2 -pbt) and includes four mononuclear com-plexes [Pt(Me2N-pbt)(C6F5 )L] (L = Me2N-pbtH) 1, p-dpbH(4-diphenylphosphino)benzoic acid) 2, o-dpbH (2-diphe-nylphosphino)benzoic acid) [Pt(Me2N-pbt)(C6F5 )(o-dpbH)]3 (unstable), and [Pt(Me2N-pbt)(o-dpb)] 4, as well as oftwo binuclear derivatives [{Pt(Me2N-pbt)(C6F5 )}2(m-PRnP)][PR4 P = O(CH2CH2OC(O)C6H 4PPh 2)2 5; PR12P = O{(CH-2CH2O)3C(O)C6H 4PPh 2}2 6]. The second includes 2,6-di-fluorophenylpyridine (dfppy) and phenylquinoline (pq) aschromophores and acyclic diaminocarbene (ADC) ligandsas auxiliary ligands [Pt(C^N)Cl{C(NHXyl)(NHR)}] [C^N =dfppy (a), pq (b); R = Pr 7a, 8a, CH2 Ph 7b, 8b]. In theNMe2-pbt based complexes the phosphorescent emissionis lost in aerated solutions, owing to photoinduced electrontransfer to 3 O2 and formation 1 O2 singlet, as confirmed incomplexes 2 and 4. Here we report some of their biological activity. Cytotoxicity studies in the human cancer celllines A549 (lung carcinoma) and HeLa (cervix carcinoma)showed good activity for the ADC complexes 7 and 8. Tothe best of our knowledge, these compounds representthe first examples of cycloplatinated complexes bearingacyclic diamino carbenes with antiproliferative properties(Ref.). Accordingly, 7a, 7b and 8a altered DNA electropho-retic mobility pointing as a possible cytotoxic mechanism.NMe2-pbt complexes 2, 3 and 6 were also active againstA549 and HeLa cancer cells, with higher efficiency in A549,in contrast to 1, 4, and 5. Cytolocalization studies revealedthat the no cytotoxic ligand Me 2 N-pbtH and their deriva-tive complexes 1-6 exhibit specific accumulation in theGolgi apparatus. Furthermore, the potential photodynamicproperty of this type of complexes was demonstrated withthe non-cytotoxic complex 4, which demonstrated efficientphotoinduced cytotoxicity after irradiation. |