Effects of triclosan and its interaction with UV radiation on biomarker responses of a native species (Corydoras paleatus): ex vivo exposure of gills.

SCARCIA, P; FLOREZ, LAURA; DE LA TORRE, F.R.

Buenos Aires

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

SETAC Latinoamerica

The addition of antimicrobialagents such as triclosan (TC) in personal care products intensified itspresence in urban waste waters and therefore into the aquatic environment. Moreover,in presence of UV radiation (eg. sunlight), TC has been shown to degradate intotwo dioxins: 2,7-dibenzodichloro-p-dioxin and 2,8-dibenzodichloro-p-dioxin, whichare more toxic than the parent compound. The effect of TC and its interactionwith UV radiation were assessed on biomarker responses of a native species (C. paleatus) after ex vivo exposure of gills. The biomarkers studied were the enzymatic activitiesof glutathione-S-transferase (GST) and catalase (CAT), total antioxidantcapacity against peroxyl radicals (ACAP) and lipid peroxidation levels(thiobarbituric acid reactive substances, TBARS). Stock solution of TC was dissolvedin methanol, two nominal concentrations 340μg/L (TC1) and 1mg/L (TC2) were tested. A total of 20fish were sacrificed, and the gills were dissected and asigned to fourtreatment groups:  saline for fresh-waterfish as control (C); methanol in saline (0,05%) (Co.sv); TC1 and TC2. Alltreatments were prepared in two sets: a dark set (without UV light incidence),and an UV set (solutions under ultraviolet radiation). Then the gills were keptunder continuous stirring for 1h at 25°C. Statistical differences between treatmentsand UV or dark condittion were determined using a two way analysis of variance (p<0,05) followed by Tukey?s test. No significant differencesbetween the parameters of Co and Co.sv groups, nor effect of UV radiation inthese groups were detected. TC exposure showed a significant increment (53%) inenzymatc activity of CAT respect to Co group, being higher after exposure to UVradiation. A similar response was observed in GST, mainly after UV exposure(75% TC1 and 94% TC2). On the other hand, in TC2 exposure, a decrease in totalantioxidant capacity and an increase in TBARS levels (2.5 TC2 and 5.5 TC2+UVtimes more than in Co) were detected. In addition, TBARS levels were doubled inboth TC concentrations with UV radiation respect dark condition. These resultssuggested that ex vivo exposure of C. paleatus gills to TC promoted changesat biotransformation and oxidative stress levels in both concentrations, whichwere not enough to prevent oxidative damage to lipid levels. At the same time,most of these changes were intensified after the effect of UV radiation on TCsolutions.