EFFICACY ASSESSMENT OF A YEAST CELL WALL BASED PRODUCT IN REDUCING THE MYCOTOXINS ORAL BIOAVAILABILITY IN RATS

In addition to the immunomodulatory and antimicrobial properties, yeast cell walls (YCWs) are widely used as feed additives for mycotoxin control. YCW are known to adsorb ZEA, while data on other toxins are conflicting. In this study, a new YCW product was developed to sequester a large spectrum of mycotoxins (AFB1, ZEA, OTA and FB1), and its efficacy was assessed first in vitro by the isotherm approach, and then in vivo with rats. The product at 0.5% w/v dosage adsorbed simultaneously up to 80% ZEA, 65% OTA, 40% FB1 and 10% AFB1 from multi-mycotoxins buffers containing 1 µg/mL of each toxin. The adsorption isotherm approach allowed us to study the adsorption mechanism and to determine the parameters affecting mycotoxin uptake, i.e., type and toxin concentration, pH of the medium and adsorbent concentration. For the study with rats (0.3 kg initial BW), each mycotoxin was administered singularly by a single oral intragastric bolus containing the mycotoxin +/- the product. Two groups of rats were used for each mycotoxin: the control groups received the mycotoxins at the dose of 12, 1, 0.5 and 0.12 mg/kg BW for FB1, ZEA, OTA or AFB1, respectively; while the treated groups received the same dose of mycotoxins with the YCW (0.5% w/w of feed consumption). Feed intake was 100 g feed/kg BW. After toxin administration, rats were housed individually in metabolic cages to collect urine at different time points (4-72h for AFB1, ZEA and FB1; 4-320 h for OTA). The mycotoxin biomarkers (AFM1, ZEA and its metabolites of phase I biotransformation i.e., ?-ZOL, ?-ZOL and ?-ZAL, OTA and FB1) were determined in urine by in-house validated HPLC/UHPLC methods. Mycotoxin content in urine was normalized to the respective creatinine concentration. Toxicokinetic parameters, i.e., area under the curve over 72/320h (AUC0->t) and maximal urine concentration (Cmax) were calculated for target mycotoxins/metabolites and were used to compare control and treatment groups. The YCW reduced the urinary excretion of ZEA, FB1 and OTA, but it was ineffective for AFB1. In particular, AUC was significantly reduced by -50% for OTA (p=0.014) and -42% for FB1 (p=0.048), while Cmax value was reduced by -79% (p<0.029) for ZEA and its metabolites. Taking into account overall findings, a good relationship was observed between in vitro and rat trials, and it can be concluded that the YCW may protect animals from the harmful effects of multi-mycotoxins contaminated feeds.