Effects of dietary canthaxanthin on ultraviolet radiation stress in prawn Artemesia longinaris

Abstract

The aims of this research were to investigate the effects of diets with added synthetic canthaxanthin (10% parafarm) and to evaluate its possible protective role under ultraviolet radiation (UVR) in prawn Artemesia longinaris. Three isoproteic and isolipidic diets (41% protein and 12% lipid) containing 0 (C0), 100 (C100), and 300 (C300) mg of canthaxanthin kg-1 of diet were prepared. Before initiating the radiation experiment, prawns were fed with the different diets for a period of 21 d in order to determine a possible accumulation of carotenoids. Afterwards, animals were exposed to two radiation treatments for 7 d: a) photosynthetically active radiation (PAR, 400-700 nm), and b) total radiation (PAR+UVR, 280-700 nm), under controlled conditions (19 ± 2 °C, salinity = 33, pH = 7). In animals exposed to PAR+UVR treatment, survival varied between 50 and 83.33% with the highest value in animals fed diet C300. At the end of the experiment, significant statistical differences were registered in integument carotenoid concentration. Under UVR stress, the highest decrease in non-polar carotenoid and esterified astaxanthin were recorded in prawns fed diets containing canthaxanthin. Scavenging properties were evaluated by electron resonance spectroscopy (EPR) using the stable 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical. Prawns fed with C300 showed the greatest activity to quench DPPH. Results suggested that dietary canthaxanthin could be acting as an antioxidant against reactive oxygen species and produced high tolerance under UVR stress.