Photochemical properties and membrane affinity of decyl-pterins

MARIA JOSÉ SOSA; MARIA NOEL URRUTIA; NILUKSHA WALALAWELA; ALEXANDER GREER; ANDRÉS H. THOMAS; MARIANA VIGNONI

La Plata, Buenos Aires

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofísica (SAB).; 2018

Sociedad Argentina de Biofísica (SAB).

Pterins are a family of heterocyclic compounds, which are present in biological systems and play different roles ranging from pigments to enzymatic cofactors for numerous redox and one-carbon transfer reactions.1,2 Pterins are not soluble in organic solvents and are only slightly soluble in water. Therefore, a new series of alkyl chain [-(CH2)9CH3] pterin conjugates have been synthesized and their photochemical and photophysical properties were studied.3 Interestingly, these properties changed in comparison with the properties of the parent compound Pterin (Ptr).4In addition, the interaction of these compounds with lipid biomembranes was investigated. Size exclusion chromatography experiments showed that Ptr is not encapsulated inside the large unilamellar vesicles (LUVs) and can freely pass through the lipid membranes. On the other hand, decyl-pterins efficiently intercalate in LUVs, and therefore, their binding constants were obtained by fluorescence emission titration curves. Moreover, fluorescence spectra suggest that the fluorophore of decyl-pterins anchored to the biomembrane is in an aqueous environment.In conclusion, decyl-chain conjugation to pterins dramatically increases their lipophilicity, while keeping their photochemical properties. This is a good indicator of their potential use as photosensitizers in biomembranes.References1. Pfleiderer, W., Natural pteridines-a chemical hobby, in: J.E. Ayling, M. Gopal Nair, C.M. Baugh (Eds.), Chemistry and Biology of Pteridines and Folates, vol. 338, Plenum Press, New York 1993, pp. 1?16.2. Kappock, T. J., and Caradonna, J. P. (1996) Pterin-dependent aminoacid hydroxylases. Chem. Rev. 96, 2659−2756.3. Vignoni, M.; Walalawela, N.; Bonesi, S. M.; Greer, A.; Thomas, A. H., Lipophilic Decyl Chain?Pterin Conjugates with Sensitizer Properties. Mol. Pharm. 2018, 15 (3), 798-807.4. Lorente, C.; Thomas, A. H., Photophysics and photochemistry of pterins in aqueous solution. Acc. Chem. Res. 2006, 39 (6), 395-402.