Effects of curcuminoids on the toxicity and mammary excretion of Aflatoxins and their metabolites in dairy cows

Aflatoxins (AFs) are mycotoxins synthesized by Aspergillus spp. They are widespread dangerous contaminants of food and feed commodities exhibiting a large array of toxic effects upon the bioactivation by drug metabolizing enzymes. Among AFs, AFB1 is the most important compound in terms of prevalence and toxicity for both humans and farm animals. Moreover, AFM1, a metabolic derivative of AFB1 which is found in milk of dairy cows exposed to a AF-contaminated diet, poses a further health risk for the consumer. There is therefore an increasing interest towards compounds able to negatively (e.g AhR ligands) and/or positively modulate enzymes involved in AF toxicokinetics. Among the latter, curcuminoids from turmeric (Curcuma longa) are receiving growing attention, based on their ability to reduce the generation and/or to increase the inactivation of toxic AF metabolites. In humans and mice, AFB1 is also reported to be a substrate of the transport protein ABCG2, which is mostly expressed in lactating mammary gland and might be negatively modulated by curcuminoids. Little is known about the role of this transporter in AF metabolite excretion in dairy milk. Likewise, the in vivo effects of curcumin in ameliorating AFB1 toxicity has been documented in rats and broiler chicks, but no data are available for dairy cows. Based on these premises, the main goal of the project is to investigate the role of curcuminoids in the modulation of AFB1 toxicity and kinetics in the bovine species. More in details, the first objective is to characterize the in vitro modulation of AFB1 toxicity and metabolism triggered by curcuminoids and, where appropriate, by AhR ligands (i.e. PCB 126). This goal will be achieved through cytotoxicity tests and the study of gene (Real Time-PCR) and protein (Western blotting) modulation in different cell lines (e.g. BME-UV1, primary bovine mammary, granulosa and liver cell cultures). The role played by bovine ABCG2 in AFM1 absorption/excretion and the modulation triggered by curcuminoids and/or AhR ligands will be investigated in engineered BME-UV1 cells and Caco2-cells by transwell culturing technique. Finally, a field study with naturally contaminated feed will assess whether and to what extent the dietary supplementation with turmeric powder may lower milk excretion of AF metabolites in dairy cows. Levels of AF and their metabolites in feed, milk and culture media will be measured by appropriate analytical techniques (HPLC, UPLC MS-MS). The results of our in vitro and field studies are expected to represent an important step toward a more sustainable livestock production system and preservation of animal and human health with obvious economic and social benefits to the different stakeholders (breeders, consumers, public health services). The possible practical applications rely on the possibility to use natural compounds (curcuminoids) to lower AF toxicity in cows and reduce milk excretion of AFM1.