4-HEXYLRESORCINOL AS INHIBITOR OF SHRIMP MELANOSIS - EFFICACY AND RESIDUES STUDIES - EVALUATION OF POSSIBLE TOXIC EFFECT IN A HUMAN INTESTINAL IN-VITRO MODEL (CACO-2) - PRELIMINARY SAFETY ASSESSMENT

Studies were performed on the efficacy, residues and in vitro enterocy te toxicity of 4-hexylresorcinol (4-HR), which could be utilized as an inhibitor of shrimp melanosis (black spot). Mediterranean sea shrimp (Parapaeneus longirostris) were treated with solutions of 4-HR in sea- water, at three different concentrations, 25, 50 or 100 mg/kg of shrim p, to test its antioxidative property. As a comparison a group of shri mp was treated with sodium metabisulphite (1 g/kg), while another grou p was left untreated. 4-HR showed a marked ability to inhibit or slow down melanosis (black spot) in shrimp;,. the most effective concentrat ion was 100 mg/kg within an optimum period of 7 days but with effects up to the tenth day. During first 5 days, 4-HR residues in the edible part of the shrimp showed a fast decrease in all three groups, going f rom initial average values of 20 mg/kg at 0 time, to 0.9 in the group treated at 25 mg/kg; from 42 to 1.8 mg/kg in the group at 50 mg/kg and from 85 to 1.9 mg/kg in the group at 100 mg/kg. In vitro studies on e nterocyte-like Caco-2 cells did not indicate any cytotoxic effect up t o a concentration of 50 mu g/ml. Moreover, no inhibition of protein sy nthesis was observed, which lends further support to the absence of si gnificant damage to the intestinal mucosa induced by 4-HR. The availab le database on 4-HR pharmacology and toxicology is inadequate to deter mine even a provisional ADI. There is negative evidence of carcinogene sis and no significant untoward effects were observed in humans when i t was used as an anthelmintic. However, it is Mot possible to determin e a NOEL for non-genotoxic effects. 4-HR could become an interesting a lternative to the use of sulphites to prevent black spot. However, a m ore complete database is needed to achieve a regulatory evaluation.