ISLA Maria Ines
congresos y reuniones científicas
Antioxidant activity of mycosporine-like amino acids (MAAs) from marine dinoflagellates.
FLORES M.R., ISLA M.I., FARÍAS M.E. ,HELBLING E.W.
Congreso; 11thEuropean Society for Photobiology Congress, France; 2005
European Society for Photobiology
We evaluated the effects of ultraviolet radiation (UVR, 280-400 nm) on growth and production of UV-absorbing compounds of two marine dinoflagellates: Gymnodinium chloroformis and Heterocapsa triquetra. Both species were incubated in an illuminated chamber (20°C; 66, 15, and 0.7 W m-2 of PAR, UV-A, and UV-B, respectively) for about 10 days under two radiation treatments (PAR and PAR+UVR). There was no significant increase in the content of MAAs in G. chloroformis; in H. triquetra, however, the concentration of MAAs (mainly shinorine, determined by HPLC techniques) increased almost 4 times after 8 days of exposure to UVR, suggesting an UVR-induced accumulation. The antioxidant activity of H. triquetra extracts were tested by in vitro methods such as b-carotene linoleate model and 1,1-diphenyl-2 picrylhydrazyl (DPPH) radical scavenging. Hydroxyl radical and superoxide anion scavenging were determined by measuring competition between deoxyribose and the extract for hydroxyl radicals generated from the Fe-3/ascorbate/EDTA/ H2O2 system and by xanthine oxidase system, respectively. The extract showed inhibitory activity of b-carotene bleaching and acted as primary antioxidant, being capable of donating hydrogen to the free radicals (IC25 3,8 ng/ml), leading to non-toxic species and therefore to inhibition of the propagation phase of lipid oxidation. The extracts also showed scavenging activity of superoxide anion and hydroxyl radical, suggesting that MAAs might protect H. triquetra cells against oxidative stress. Active extracts of H triquetra may be an alternative synthetic antioxidant that could be used as additives for nutrition, pharmaceutical and cosmetic purposes.