Issue 11, 2009
From the journal:

Photochemical & Photobiological Sciences

The photosensitizing activity of lumazine using 2′-deoxyguanosine 5′-monophosphate and HeLa cells as targets†

M. Paula Denofrio,a   Sonja Hatz,b   Carolina Lorente,a   Franco M. Cabrerizo,*c   Peter R. Ogilby*b  and  Andrés H. Thomas*a  

* Corresponding authors

a INIFTA, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET. C.C. 16, Suc. 4, La Plata, Argentina
E-mail: athomas@inifta.unlp.edu.ar

b Center for Oxygen Microscopy and Imaging, Department of Chemistry, University of Aarhus, Århus, Denmark
E-mail: progilby@chem.au.dk

c CIHIDECAR, CONICET, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, 3p, Ciudad Universitaria, Buenos Aires, Argentina
E-mail: fcabrerizo@qo.fcen.uba.ar

Abstract

Lumazines are an important family of heterocyclic compounds present in biological systems as biosynthetic precursors and/or products of metabolic degradation. Upon UV irradiation, the specific compound called lumazine (pteridine-2,4(1,3H)-dione) is able to generate singlet oxygen (1O2), which is one of the main chemical species responsible for photodynamic effects. To further assess the photosensitizing capability of lumazine (Lum) experiments were performed using the nucleotide 2′-deoxyguanosine 5′-monophosphate (dGMP) and, independently, cervical cancer cells (HeLa cell line) as targets. In the dGMP experiments, the data revealed that dGMP indeed undergoes oxidation/oxygenation photoinduced by Lum. Moreover, dGMP disappearance proceeds through two competing pathways: (1) electron transfer between dGMP and excited-state Lum (Type I process) and (2) reaction of dGMP with 1O2 produced by Lum (Type II process). The multistep processes involved are convoluted and susceptible to changes in experimental conditions. The independent studies with HeLa cells included fluorescence analysis of cell extracts and phototoxicity experiments performed at the single-cell level. Results showed that, upon Lum uptake and irradiation, photodynamic effects occur. In particular, the mitochondria and cell membrane were perturbed, both of which reflect key stages in cell death. The data reported herein illustrate how the irradiation of an endogenous biological compound can have various effects which, depending on the system, can be manifested in different ways.

Graphical abstract: The photosensitizing activity of lumazine using 2′-deoxyguanosine 5′-monophosphate and HeLa cells as targets

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Article information

DOI
https://doi.org/10.1039/B9PP00020H
Article type
Paper
Submitted
11 Jun 2009
Accepted
21 Aug 2009
First published
17 Sep 2009

Photochem. Photobiol. Sci., 2009,8, 1539-1549

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The photosensitizing activity of lumazine using 2′-deoxyguanosine 5′-monophosphate and HeLa cells as targets

M. P. Denofrio, S. Hatz, C. Lorente, F. M. Cabrerizo, P. R. Ogilby and A. H. Thomas, Photochem. Photobiol. Sci., 2009, 8, 1539 DOI: 10.1039/B9PP00020H

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