INVESTIGADORES
CABRERIZO Franco Martin
congresos y reuniones científicas
Título:
Photophysical and photobiological properties of [Re(CO)3(phen)(nHo)]CF3SO3 complex, nHo = norharmane
Autor/es:
IVÁN MAISULS; FRANCO M. CABRERIZO; PEDRO M. DAVID GARA; GUILLERMO FERRAUDI; BERND EPE; GUSTAVO T. RUIZ
Lugar:
Santiago
Reunión:
Conferencia; 25st I-APS (Inter-American Photochemical Society) Conference on Photochemistry; 2016
Resumen:
b-carbolines are a group of naturally occurring alkaloids derived from9H-pyrido[3,4-b]indole or norharmane (nHo). These alkaloids are widespread inbiological systems, having an active role in different photosensitizingprocesses.Tricarbonyl rhenium complexes with polypyridyl and bioactive moleculesas ligands have an excellent thermal and photochemical stability being, thus,appealing candidates for diverse applications such as photodynamic therapy,anti-cancer drugs and radiotherapy.We show herein preliminaryresults about emission spectroscopy and flash photolysis studies of a novel Re(CO)3(phen)(nHo)+complex in different solvents. Also we show how this complex interacts with DNAunder UVA light. UV-Vis absorptionspectra show intense bands in the UV region of the spectra. These spectralfeatures are almost identical with those found in the electronic spectrum ofthe free nHo ligand and are therefore assigned to IL excitations in the nHoligand. The absorption band observed in the visible region exhibit typicallyintense and solvatochromic MLCT transitions from the metal dp to the lowest lying ligand p* orbital. Emissionspectrum of the complex, recorded in methanol, shows an emitting band at ~450 nm due to the deactivation of the lower nHoligand-localized state, as it was described for free nHo. Emission from MLCTRe→phenexcited state have been observed in 530-560 nm range. Moreover, the observedluminescence shows a strong dependence on the oxygen concentration. Both emissionquantum yield and lifetime values, obtained in all solvents tested, arecompared with those reported for free nHo.The absorption patterns of thetransient were registered by laser flash photolysis experiments, lexc = 351 nm. Theabsorption spectra in MeOH of the transient showed two maxima at 380 and 460nm, lifetime ~ 780 ns(oxygen free solution of the complex). The redox activity of the exited statewas measured by reductive quenching using TEA. Additionally, the efficiency of singletoxygen production was determined in acetonitrile.In addition, the capability of Re(CO)3(phen)(nHo)+ complex to induce damage in cell-free DNA upon UVAexcitation was examined. The damage profilewas determined by using the PM2 assay where treated DNA was incubated with repair enzymes that recognize specifictype of damage or DNA lesions. The type and extent of DNA damage is analyzedtogether with photochemical, photophysical and binding properties Re(CO)3(phen)(nHo)+complex. Briefly, the tested photosensitizer induces single and double strandbreaks (SSB and DSB), oxidatively generated purine modifications (8-oxoGua,FapyGua and FapyAde) and sites of base loss (AP sites).