Study of ruthenium(II) complexes with anticancer drugs as ligands. Design of metal-based phototherapeutic agents.
The reaction of trans-[RuCl(2)(PPh(3))(3)] (Ph = C(6)H(5)) with 2-thio-1,3-pyrimidine (HTPYM) and 6-thiopurines (TPs) produced mainly crystalline solids that consist of cis,cis,trans-[Ru(PPh(3))(2)(N,S-TPYM)(2)] (1) and cis,cis,trans-[Ru(PPh(3))(2)(N(7),S-TPs)(2)]X(2) (X = Cl(-), CF(3)SO(3)(-)). In the case of TPs, other coordination isomers have never been isolated and reported. Instead, the mother liquor obtained after filtration of 1 produced red single crystals of trans,cis,cis-[Ru(PPh(3))(2)(N,S-TPYM)(2)].2H(3)O(+).2Cl(-) (2.2H(3)O(+).2Cl(-)). Selected ruthenium(II)-thiobase complexes were studied for their structural, reactivity, spectroscopic, redox, and cytotoxic properties. Single crystals of 1 contain thiopyrimidinato anions chelated to the metal center via N and S. The Ru[bond]N bonds are significantly elongated for 1 [2.122(2) and 2.167(2) A] with respect to 2 [2.063(3) A] because of the trans influence from PPh(3). The coordination pseudo-octahedron for 2 is significantly elongated at the apical sites (PPh(3) ligands). Solutions of cis,cis,trans isomers in air are stable for weeks, whereas those of 2 turn green within 24 h, in agreement with the respective redox potentials. cis,cis,trans- and trans,cis,cis-[Ru(PH(3))(2)(N,S-TPYM)(2)], as optimized through the DFT methods at the Becke3LYP level are in good agreement with experimental geometrical parameters (1 and 2), with cis,cis,trans being more stable than trans,cis,cis by 3.88 kcal. The trend is confirmed by molecular modeling based on semiempirical (ZINDO/1) and molecular mechanics (MM) methods. Cytotoxic activity measurements for cis,cis,trans-[Ru(PPh(3))(N-THZ)(N(7),S -H(2)TP)(2)]Cl(2) (4) (THZ = thiazole, H(2)TP = 6-thiopurine) and cis,cis,trans-[Ru(PPh(3))(2)(N(7),S-HTPR)2]Cl(2) (5) (HTPR = 6-thiopurine riboside) against ovarian cancer cells A2780/S gave IC(50) values of 17 +/- 1 and 29 +/- 9 microM, respectively. Furthermore, the spectral analysis of HTPYM, TPs, and their Ru(II) complexes in solution shows that intense absorptions occur in the UVA/vis region of light, whereas standard nucleobases absorb in the UVB region.
Cini
Renzo
R
Department of Chemical and Biosystem Sciences and Technologies, University of Siena, Via A. Moro 2, I-53100 Siena, Italy. cini@unisi.it
Tamasi
Gabriella
G
Defazio
Sandra
S
Corsini
Maddalena
M
Zanello
Piero
P
Messori
Luigi
L
Marcon
Giordana
G
Piccioli
Francesca
F
Orioli
Pierluigi
P
D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D018360:Crystallography, X-Ray; D004355:Drug Stability; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000473:pathology; D010084:Oxidation-Reduction; D010777:Photochemistry; D011743:Pyrimidines / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*; D013237:Stereoisomerism; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D008024:Ligands; D009942:Organometallic Compounds; D011743:Pyrimidines; D012428:Ruthenium