Effects ofSanionia uncinataextracts 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) O(2)(•-), 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) Cu(2+)/H(2)O(2), 94% (AE) and 100% (HE) (P<0.05), and (ii) SnCl(2), 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/Cu(2+) could have also been triggered by other mechanisms.

Evaluation of the acute toxicity, phototoxicity and embryotoxicity of a residual aqueous fraction from extract of the Antarctic moss Sanionia uncinata

“…We have also demonstrated positive correlation between protective effect against UVR and phenolic compound present in extracts. Water-extractable compounds seem to contribute on photoprotection of this Antarctic moss [10, 13, 14]. Given the above context, the goal of this paper is to explore the potential photoprotective, cytotoxic and embryotoxic effects of residual AF from the polar moss S. uncinata .…”

“…Loeske from King George Island is directly exposed to high levels of solar radiation during the summer (December to late March), when soil and air temperatures typically remain above freezing. At sub-Antarctic islands such as the collection site, UVR levels reaching the surface are about four times higher in the summer (in terms of maximum daily UV index) than in the winter or autumn [10]. The influence of the Antarctic ozone hole on surface climate is most pronounced during the austral summer season [11].…”

“…Our research group has showed that aqueous and hydroethanolic (HE) extracts from S. uncinata act as protectors against plasmid DNA cleavage by way of scavenging of superoxide radical anion and hydroxyl radical [10], and do not induce point mutations [13]. Nevertheless, these extracts induced an increase in DNA cleavage via a Fenton-like reaction [10]. We also demonstrated that the inhibition of ROS-damage by S. uncinata has been associated with the flavonoid constituents such as flavone, flavanone, flavonols, chacones and catechin [14].…”

Photoprotective and toxicological activities of extracts from the Antarctic moss Sanionia uncinata

“…The sampling site was described before. [ 7 ] The S. uncinata was identified by Dr. Denise Pinheiro da Costa of the Botanical Garden Research Institute of Rio de Janeiro (Brazil) and a voucher specimen was deposited (Herbarium of the State University of Rio de Janeiro, Brazil, H-RJ 11,811).…”

“…However, both extracts induced DNA cleavage by Fenton-like reactions, indicating that formulations involving metal ions must be strictly avoided in the direct use of these extracts. [ 7 ]…”