Adsorption and detoxification of ochratoxin A using hydrophobic bentonite clay

Mycotoxins such as ochratoxin A (OTA) are hazardous chemicals produced from fungi that frequently contaminate feed ingredients, and this contamination can result in significant economic loss, disease and death. Given the persistent nature of OTA, this study was designed to provide effective and potentially scalable strategies to mitigate acute OTA toxicity using organoclay. The study explores the adsorption behavior of OTA on active binding surfaces of four organoclay composites that were synthesized by modifying sodium bentonite clay surfaces with different amounts of a hydrophobic quaternary ammonium compound (QAC). This modification serves to immobilize and stabilize the QAC. The study evaluates key thermodynamics, kinetics and binding markers including the Gibbs free energy (ΔG), adsorption capacity, enthalpy (ΔH), and binding affinity of these clays for OTA. Additionally, the protective role of these organoclays was evaluated using a sensitive ecotoxicology model. At gastric pH (pH 2), the organoclays demonstrated high adsorption capacities for OTA ranging between 0.34 and 0.51 mol kg^-1 versus parent clay (0.20 mol kg^-1). At intestinal pH (pH 6), the organoclay binding capacities were higher than the parent clay indicating that the modification of parent clay with QAC played a critical role in improving its adsorptive performance for OTA. Thermodynamic parameters indicated that the binding reaction was exothermic and thermodynamically favorable with ΔG values between -23.40 and -28.07 kJ mol^-1 and ΔH values ranging from -13.76 kJ mol^-1 to -24.31 kJ mol^-1. Importantly, organoclay treatment protected hydra from OTA lethality by 95% to 100%. These findings established the proof-of-concept that OTA interactions with organoclay resulted in the prevention of OTA toxicity in hydra. Based on these findings, further studies are warranted to justify the applications and efficacy of these organoclays for short-term treatment during acute outbreaks of ochratoxicosis.