Effects of Sanionia uncinata extracts in protecting against and inducing DNA cleavage by reactive oxygen species

Abstract

When mosses are exposed to increased quantities of ultraviolet (UV) radiation, they produce more secondary metabolites. Antarctica moss Sanionia uncinata (Hedw.) Loeske has presented high carotenoid contents in response to an increase in UVB radiation. This moss has been recommended as a potential source of antioxidants. In the present work, the protective and enhancing effects of aqueous (AE) and hydroalcoholic (HE) extracts of S. uncinata on the cleavage of supercoiled DNA were evaluated through topological modifications, quantified by densitometry after agarose gel electrophoresis. Total phenolic contents reached 5.89 mg/g. Our data demonstrated that the extract does not induce DNA cleavage. Furthermore, both extracts showed antioxidant activity that protected the DNA against cleavage induced by (i) O₂^•−, 89% (AE) and 94% (HE) (P < 0.05), and (ii) .OH, 17% (AE) and 18% (HE). However, the extracts intensified cleavage induced by Fenton-like reactions: (i) Cu²⁺/H₂O₂, 94% (AE) and 100% (HE) (P < 0.05), and (ii) SnCl₂, 62% (AE) and 56% (HE). DNA damages seem to follow different ways: (i) in the presence of Fenton-like reactions could be via reactive oxygen species generation and (ii) with HE/Cu²⁺ could have also been triggered by other mechanisms.

Keywords:

• Sanionia uncinata
• Reactive oxygen species
• DNA cleavage
• Antioxidants
• Antarctica

Acknowledgments

The authors wish to thank Dr Denise Pinheiro da Costa from the Botanical Garden Research Institute of Rio de Janeiro (Brazil) for the identification of the moss. This work was supported by CNPq (Brasília, Brazil) and Faperj (Rio de Janeiro, Brazil). We also thank PROANTAR (CNPq556971/2009–4) and INCT-Criosfera for allowing sampling in Antarctica.