Photochemical properties and membrane affinity of decyl-pterins

M. JOSÉ SOSA; M. NOEL URRUTIA; N. WALALAWELA; ALEXANDER GREER; ANDRÉS H. THOMAS; MARIANA VIGNONI

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofísica; 2018

Pterins are a family of heterocyclic compounds, which are present in biologicalsystems and play different roles ranging from pigments to enzymatic cofactors fornumerous redox and one-carbon transfer reactions.1,2 Pterins are not soluble inorganic solvents and are only slightly soluble in water. Therefore, a new series ofalkyl chain [-(CH2)9CH3] pterin conjugates have been synthesized and theirphotochemical and photophysical properties were studied.3 Interestingly, theseproperties changed in comparison with the properties of the parent compoundPterin (Ptr).4In addition, the interaction of these compounds with lipid biomembranes wasinvestigated. Size exclusion chromatography experiments showed that Ptr is notencapsulated inside the large unilamellar vesicles (LUVs) and can freely passthrough the lipid membranes. On the other hand, decyl-pterins efficientlyintercalate in LUVs, and therefore, their binding constants were obtained byfluorescence emission titration curves. Moreover, fluorescence spectra suggestthat the fluorophore of decyl-pterins anchored to the biomembrane is in anaqueous environment.In conclusion, decyl-chain conjugation to pterins dramatically increases theirlipophilicity, while keeping their photochemical properties. This is a good indicatorof their potential use as photosensitizers in biomembranes.Contact: mjsosa@inifta.unlp.edu.arReferences1. 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 aminoacidhydroxylases. Chem. Rev. 96, 2659−2756.3. Vignoni, M.; Walalawela, N.; Bonesi, S. M.; Greer, A.; Thomas, A. H., LipophilicDecyl Chain?Pterin Conjugates with Sensitizer Properties. Mol. Pharm. 2018, 15(3), 798-807.4. Lorente, C.; Thomas, A. H., Photophysics and photochemistry of pterins inaqueous solution. Acc. Chem. Res. 2006, 39 (6), 395-402