Phenolics from Phagnalon inhibit oxidation of deoxyguanosine in vitro

It is well known that oxidizing agents can modify the structure of different key biomolecules. Proteins and nucleic acids may suffer alterations which sometimes are detrimental for their function, or lead even to the rupture of the molecule. Specially, oxidative damage of nucleic acids is related to inflammation, cancer, and neurodegenerative diseases [1]. The present communication deals with the protective effect that some phenolic principles exert on the oxidation of the nucleoside, 2′-deoxyguanosine (dG), driven by either hypochlorite or activated human neutrophils. The hydroxycinnamate, 3,5-dicaffeoylquinic acid (DCA), the terpenic hydroquinone, 2-isoprenylhydroquinone-1-O-glucoside (IHG), and the flavonoid, chrysoeriol-7-O-glucoside (C7G) were isolated and identified by ourselves from Phagnalon rupestre [2] and P. saxatile (Asteraceae). Oxidation of dG to 8-hydroxy-dG and subsequent degradation products was performed with 0.9% NaOCl, 10% active chlorine, or with neutrophils stimulated with phorbol ester. Samples were analyzed by RP18- HPLC eluting with 10% MeOH, buffered with ammonium formate pH 5.0. The most active compound on NaOCl oxidation was IHG (74% inhibition at 0.1 mM), whereas C7G reached the highest efficacy in the leukocyte model (50% inhibition at 0.015 mM).

Acknowledgements: Spanish Ministry of Science and Technology (SAF 2006–06726) and Generalitat Valenciana (GV 353/06).

References: 1. Halliwell, B. (2007) Biochem. J. 401:1–11.

2. Góngora, L. et al. (2002) Planta Med. 68:561–564.