Evaluating the persistence of malachite green residues in tilapia and pacu fish.

Although banned in food-producing animals, residues of malachite green (MG) and its primary metabolite, leucomalachite green (LMG), have been found in fish due to illegal use in aquaculture and the release of industrial wastewater, which represent a serious risk to food and environmental securities. This study aimed to investigate the residue depletion profile of MG and LMG in edible tissues of Nile tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus) cultured simultaneously under the same environmental conditions to support control measures in case of abuse. An analytical method involving QuEChERS sample preparation and liquid chromatography coupled to tandem mass spectrometry was developed, validated, and applied to quantify MG and LMG residues in fish fillets from two depletion experiments after treatment by immersion bath (MG at 0.10 mg L-1 for 60 min). During the experiment, the average water temperature was 30 ºC, while the pH was 6.9. The method is selective, precise (CV = 0.4 - 22%) and accurate (recovery 92 - 114%). The limits of detection and quantification are 0.15 and 0.5 ng g-1, respectively. In both species, the sum of MG and LMG residues were quantified up to the 32nd day post-exposure, and the concentrations were significantly higher in the pacu fillets (up to 3284 ng g-1) than in Nile tilapia (up to 432 ng g-1). The sums of MG and LMG residues were below 2 ng g-1 at 44 days and 342 days for Nile tilapia and pacu, respectively - the Minimum Required Performance Limit (MRPL) for analytical methods intended to monitor forbidden substances in food according to old European Commission guidelines. The persistence of MG residues in pacu may be attributed to its higher lipid content, which favors the accumulation of the non-polar metabolite LMG. These results provide insights into the concern about human, animal, and environmental health risks resulting from unauthorized use or aquatic contamination by industrial wastewater containing MG residues.

Levamisole incorporation in fish feed - Ensuring the medication dose and avoidance of leaching into the water.

Levamisole, an anthelmintic and immunostimulant drug, has been studied as a promising alternative for aquaculture use. While oral administration through feeding is the main route of administration in fish farming, no studies evaluating methods of levamisole incorporation into the feed have been reported so far. Therefore, this study aimed to evaluate potential procedures for levamisole incorporation in extruded fish feed using ethyl cellulose, gelatin, or vegetable oil, to avoid drug leaching to the water during the animal's medication. A suitable LC-MS/MS method was optimized (full factorial design), validated, and applied to evaluate the efficiency of the process, the homogeneity of the drug concentration, and the leaching rate. The method has been demonstrated to be selective, precise (RSD < 4.9%), accurate (recovery > 98.4%), and linear (r > 0.99, 125-750 mg kg-1). The incorporation procedures using the three coating agents showed high incorporation efficiency (70%) and a homogeneous drug concentration among the extruded feed pellets. A low levamisole leaching rate was verified in the feed prepared using the ethyl cellulose coating procedure (4.3% after 15 min of immersion in the water). On the other hand, fish feed coated with gelatin and oil resulted in a high leaching rate (30-35% after 15 min). Thus, this study shows that coating ethyl cellulose may be a promising procedure for levamisole incorporation in fish feed and with the potential to enhance its use in animal production while reducing environmental contamination.

Residue Depletion Profile and Estimation of Withdrawal Period for Sulfadimethoxine and Ormetoprim in Edible Tissues of Nile Tilapia (Oreochromis sp.) on Medicated Feed.

Sulfadimethoxine (SDM) and ormetoprim (OMP) are antimicrobials used in combination to treat bacterial infections in fish farming. The use of this drug combination is not yet regulated in some countries, such as Brazil. Due to the lack of regulated drugs for aquaculture in Brazil, this study investigated the residue depletion profile of SDM and OMP in Nile tilapia (Oreochromis sp.) after oral administration. Fish were treated with medicated feed containing a 5:1 ratio of SDM:OMP at the dose of 50 mg kg BW-1 for five consecutive days with an average water temperature of 28 °C. The drugs were incorporated into the feed by using a gelatin coating process which promoted homogeneity in drug concentration and prevented the drug leaching into the water during medication. The SDM and OMP determination in fish fillets (muscle plus skin in natural proportions) was performed using the QuEChERS approach followed by LC-MS/MS quantification. The analytical method was validated according to Brazilian and selected international guidelines. A withdrawal period of 9 days (or 252 °C days) was estimated for the sum of SDM and OMP residues at concentration levels below the maximum residue level of 100 µg kg-1.

Combination of extractive techniques followed by HPLC-MS/MS analysis to monitor ent-agathic acid in fish treated with Copaifera duckei Dwyer.

Plants are used as therapeutic alternatives in Veterinary Medicine, including therapies for food-producing animals. However, these medicinal resources can sometimes contain dangerous substances, and when used in animals that supply food, they stand out from the point of view of food safety. The diterpene ent-agathic acid, a component of Copaifera duckei oleoresin, is an example of substances already described with toxic activity in mammals. Thus, this study aimed to propose combining two extractive techniques followed by high-performance liquid chromatography coupled mass spectrometry analysis to monitor residues of ent-agathic acid in Piaractus mesopotamicus fillet treated in an immersion bath with Copaifera duckei oleoresin. An optimized combination of solid-liquid extraction (using acidified acetonitrile) and dispersive liquid-liquid microextraction (using acidified water and chloroform as dispersive and extracting solvent, respectively) was performed to recover the target analyte, added to the development of HPLC-MS/MS method with adequate validation parameters to quantify the ent-agathic acid present in the fish fillet. In vivo tests of residual persistence of ent-agathic acid in fishes treated with C. duckei oleoresin were performed, indicating the non-detection of the target diterpene (< 6.1 µg/mL). The combined extractive procedure followed by quantitative analysis in the in vivo test of residual persistence of the target analyte in fish indicated the absence of ent-agathic acid in all samples. Thus, the data found might contribute to understanding the use of oleoresins from C. duckei as an alternative to traditional veterinary products.

The association of modified QuEChERS and DLLME to offer high analytical detectability to assess residual depletion profile of erythromycin in fish.

An analytical method for the determination of erythromycin A (ERY) residues in fish fillet was developed, optimized, and validated employing a modified QuEChERS procedure associated to DLLME technique as a preconcentration step. The obtained LOD and the LOQ were 0.1 µg kg-1 and 1 µg kg-1, respectively. The validated method provides linearity in the range of 1 to 20 µg kg-1, precision (CV < 6.3 %) and accuracy (recovery ranging from 103 to 110 %). The procedure was applied in an experimental study to evaluate the residual depletion profile of ERY in fish (Piaractus mesopotamicus) after oral administration. The treatment was carried out at a daily dose of 100 mg (kg BW)-1 of ERY, for 7 consecutive days and with an average water temperature of 30 °C. A withdrawal time of 240°-day was estimated for eliminating ERY residues at concentration levels below the maximum residue limit considered (MRL 100 µg kg-1).

Ethnoveterinary for food-producing animals and related food safety issues: A comprehensive overview about terpenes.

Alternatives to the use of conventional veterinary drugs in food-producing animals have gained attention, such as the use of natural products (NPs), mainly to soften the risks to the animal, the environment, and consumer's health. Although NPs have consistent advantages over conventional drugs, they cannot be considered risk free under food safety matters. In this way, this document presents a comprehensive overview of the importance of considering both the pharmacological and toxicological properties of the constituents of a NP from plants intending the standardization and regulation of its use in food-producing animals. Terpenes are the most diverse class of natural substances present in NP of vegetal origin with a broad range of biological activities that can be explored in veterinary science; however, certain plants and terpenes also have significant toxic effects, a fact that can harm the health of animals and consequently generate economic losses and risks for humans. In this context, this review gathered scientific data of vegetal species of importance to ethnoveterinary for food-producing animals, which produce terpenes, its biological effects, and their implications on food safety issues for consumers. For this, more than 300 documents were selected from different online scientific databases. The present data and discussion may contribute to the rational commercial exploration of this class of NPs in veterinary medicine.