Photosensitized electron transfer within a self-assembled norharmanes- 2’-deoxyadenosine 5’-monophosphate (dAMP) complex

MARÍA M. GONZÁLEZ; FEDERICO A.O. RASSE-SURIANI; CARLOS A. FRANCA; REINALDO PIS DIEZ; YOUSEF GHOLIPOUR; HIROSHI NONAMI; ROSA ERRA-BALSELLS; FRANCO M. CABRERIZO

ORGANIC & BIOMOLECULAR CHEMISTRY

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2012 vol. 10 p. 9359 - 9372

1477-0520

Norharmane is a compound that belongs to a family of alkaloids called β-carbolines (βCs). Thesealkaloids are present in a wide range of biological systems, playing a variety of significant photo-dependent roles. Upon UV-A irradiation, βCs are able to act as efficient photosensitizers. In this work,we have investigated the photosensitized oxidation of 2′-deoxyadenosine 5′-monophosphate (dAMP) bynorharmane in an aqueous phase, upon UV-A (350 nm) irradiation. The effect of the pH was evaluatedon both the interactions between norharmane and dAMP in the ground and electronic excited states, andon the dAMP photosensitized oxidation. A quite strong static interaction between norharmane and dAMPwas observed, especially under those pH conditions where the protonated form of the alkaloid is present( pH < 7). Theoretical studies were performed to further characterize the static complex structure. Theparticipation of reactive oxygen species (ROS) in the photosensitized reaction was also investigated andthe photoproducts were characterized by means of UV-LDI-MS and ESI-MS. All the data provided hereinindicate that electron transfer (Type I) within a self-assembled norharmane–dAMP complex is theoperative mechanism in the dAMP photosensitization.