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102 ANTIOXIDANT ACTIVITY OF DIETARY CAROTENOIDS IN DIFFERENT TISSUES OF SHRIMP Pleoticus muelleri (CRUSTACEA, PENAEOIDEA) Fenucci, J.L.*, D¨ªaz, A.C., Fern¨¢ndez Gimenez, A.V., Velurtas, S.M. and Mendiara, S.N. Facultad de Ciencias Exactas y Naturales Universidad Nacional de Mar del Plata CONICET, Funes 3350 B7602AYL, Mar del Plata, Argentina jfenucci@mdp.edu.ar Highly reactive free radicals are generated from normal cellular metabolism and from the ingestion of environmental pollutants and drugs. These free radicals react destroying the integrity of cellular membranes, enzymes and nuclear DNA. Antioxidants are able to neutralize these highly reactive free radicals, safeguarding the structural and functional integrity of cells. Carotenoids, not essential vitamins by themselves, may contribute directly or indirectly to lower the endogenous oxidative stress. The aim of this study was to determine the free radical scavenging properties in different tissues of Pleoticus muelleri fed isoproteic formulated feed containing two levels of carotenoids. Four diets were tested with 35% of crude protein; two of them were supplemented with astaxanthin (50 and 100 mg/100 g diet), and the others with ¦Á-carotene (50 and 100 mg/100 g diet). The control group was fed with a non-pigmented diet (D0). Trials were carried out in three replicate groups during 7 weeks on juveniles (5.15¡À0.941g initial weight). To analyse the oxidative stress a free radical scavenging capacity assay was developed, measuring in vitro the depletion of the persistent 2,2dipheniyl-1-picryhydrazyl radical (DPPH) by electron paramagnetic spin resonance spectrometry method. Figure 1 shows the comparative results of radical DPPH scavenging capacity of muscle and midgut gland tissues at different times. In midgut gland extracts the DPPH signal decreased drastically within 20 minutes and DPPH was effectively consumed in about 1 hour. It was determined that this tissue is a natural antioxidant having efficient protective substances and the carotenoid supplemented diets are more effective in depleting DPPH radicals. Muscle practically lacked antioxidant capacity but some was generated with ¦Â-carotene supplemented diets. It was observed that astaxanthin provides stronger antioxidant protection than ¦Â-carotene in midgut gland; after 20 minutes the depletion of DPPH was 22% and with ¦Â-carotene was 41%. Carotenoids can interrupt radical chains reactioning directly with radicals and neutralizing their effect in low oxygenated tissues. In the presence of enough oxygen carotenoids may have a different behaviour and show pro-oxidant activity; therefore in vitro it is quite important working in anoxic conditions. This assay provides an index for testing the response of biological tissues against the incoming of free radicals.

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