SPECTROSCOPIC PROPERTIES AND PHOTOREACTIVITY WITH DNA OF NEW MONOFUNCTIONAL PYRIDOPSORALENS

Abstract

Abstract— New psoralen derivatives have been synthesized in order to enhance their affinity towards DNA. The spectral properties (absorption, fluorescence emission, fluorescence quantum yield) and the photostability of pyrido[3,4‐c]psoralen are first reported. The drastic changes observed in the solubility and in the fluorescence emission when these compounds are added to native DNA give evidence of the formation of non covalent dark complexes. Upon UV irradiation (365 nm) of the complexes, a photobinding occurs. Heat denaturation and renaturation experiments of modified DNA show that only monoadducts are formed. From the analysis of their fluorescence properties the involvement of the 4′, 5′ double bond is assumed. The monofunctional character has also been established for psoralens having a fused pyridine ring in the 4′, 5′ site. On the opposite, a fused tetrahydropyrido group in the 4′, 5′ site is inefficient to inactivate this reactive site.