Zearalenone (ZEN) is a Fusarium-derived mycotoxin, exerting xenoestrogenic effects in animals and humans. ZEN and its derivatives commonly occur in cereals and cereal-based products. During the biotransformation of ZEN, its reduced metabolites, α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL), are formed; α-ZEL is even more toxic than the parent compound ZEN. Since previous studies demonstrated that ZEN and ZELs form stable complexes with β-cyclodextrins, it is reasonable to hypothesize that cyclodextrin polymers may be suitable for mycotoxin removal from aqueous solutions. In this study, the extraction of ZEN and ZELs from water, buffers, and corn beer was investigated, employing insoluble β-cyclodextrin bead polymer (BBP) as a mycotoxin-binder. Our results demonstrate that even relatively small amounts of BBP can strongly decrease the mycotoxin content of aqueous solutions (including beer). After the first application of BBP for mycotoxin binding, BBP could be completely reactivated through the elimination of ZEN from the cyclodextrin cavities by washing with a 50 v/v% ethanol-water mixture. Therefore, our study suggests that insoluble cyclodextrin polymers may be suitable tools in the future to deplete mycotoxins from contaminated drinks.

Ochratoxin A (OTA) is a toxic secondary metabolite produced by several fungal species of the genus Penicillium and Aspergillus. 2′R-Ochratoxin A (2′R-OTA) is a thermal isomerization product of OTA formed during food processing at high temperatures. Both compounds are detectable in human blood in concentrations between 0.02 and 0.41 µg/L with 2′R-OTA being only detectable in the blood of coffee drinkers. Humans have approximately a fifty-fold higher exposure through food consumption to OTA than to 2′R-OTA. In human blood, however, the differences between the concentrations of the two compounds is, on average, only a factor of two. To understand these unexpectedly high 2′R-OTA concentrations found in human blood, the affinity of this compound to the most abundant protein in human blood the human serum albumin (HSA) was studied and compared to that of OTA, which has a well-known high binding affinity. Using fluorescence spectroscopy, equilibrium dialysis, circular dichroism (CD), high performance affinity chromatography (HPAC), and molecular modelling experiments, the affinities of OTA and 2′R-OTA to HSA were determined and compared with each other. For the affinity of HSA towards OTA, a logK of 7.0–7.6 was calculated, while for its thermally produced isomer 2′R-OTA, a lower, but still high, logK of 6.2–6.4 was determined. The data of all experiments showed consistently that OTA has a higher affinity to HSA than 2′R-OTA. Thus, differences in the affinity to HSA cannot explain the relatively high levels of 2′R-OTA found in human blood samples.

Mycotoxins are toxic metabolites of filamentous fungi. Previous studies demonstrated the co-occurrence of Fusarium and Alternaria toxins, including zearalenone (ZEN), ZEN metabolites, and alternariol (AOH). These xenoestrogenic mycotoxins appear in soy-based meals and dietary supplements, resulting in the co-exposure to ZEN and AOH with the phytoestrogen genistein (GEN). In this study, the cytotoxic and estrogenic effects of ZEN, reduced ZEN metabolites, AOH, and GEN are examined to evaluate their individual and combined impacts. Our results demonstrate that reduced ZEN metabolites, AOH, and GEN can aggravate ZEN-induced toxicity; in addition, the compounds tested exerted mostly synergism or additive combined effects regarding cytotoxicity and/or estrogenicity. Therefore, these observations underline the importance and the considerable risk of mycotoxin co-exposure and the combined effects of mycoestrogens with phytoestrogens.

Beauvericin (BEA), cyclopiazonic acid (CPA), and sterigmatocystin (STC) are emerging mycotoxins. They appear as contaminants in food and animal feed, leading to economic losses and health risks. Human serum albumin (HSA) forms stable complexes with certain mycotoxins, including ochratoxins, alternariol, citrinin, and zearalenone. HSA binding can influence the toxicokinetics of xenobiotics, and albumin can also be considered and applied as a relatively cheap affinity protein. Therefore, we examined the potential interactions of BEA, CPA, and STC with HSA employing fluorescence spectroscopy, ultracentrifugation, ultrafiltration, and molecular modeling. Spectroscopic and ultracentrifugation studies demonstrated the formation of low-affinity BEA–HSA (K_a ≈ 10³ L/mol) and moderately strong CPA–HSA and STC–HSA complexes (K_a ≈ 10⁴ L/mol). In ultrafiltration experiments, CPA slightly displaced each site marker (warfarin, naproxen, and camptothecin) tested, while BEA and STC did not affect significantly the albumin binding of these drugs. Modeling studies suggest that CPA occupies Sudlow’s site I, while STC binds to the Heme site (FA1) on HSA. Considering the interactions of CPA with the site markers, the CPA–HSA interaction may have toxicological importance.

Silymarin is a mixture of flavonolignans isolated from the fruit of milk thistle (Silybum marianum (L.) Gaertner). Milk thistle extract is the active ingredient of several medications and dietary supplements to treat liver injury/diseases. After the oral administration, flavonolignans are extensively biotransformed, resulting in the formation of sulfate and/or glucuronide metabolites. Previous studies demonstrated that silymarin components form stable complexes with serum albumin and can inhibit certain cytochrome P450 (CYP) enzymes. Nevertheless, in most of these investigations, silybin was tested; while no or only limited information is available regarding other silymarin components and metabolites. In this study, the interactions of five silymarin components (silybin A, silybin B, isosilybin A, silychristin, and 2,3-dehydrosilychristin) and their sulfate metabolites were examined with human serum albumin and CYP (2C9, 2C19, 2D6, and 3A4) enzymes. Our results demonstrate that each compound tested forms stable complexes with albumin, and certain silymarin components/metabolites can inhibit CYP enzymes. Most of the sulfate conjugates were less potent inhibitors of CYP enzymes, but 2,3-dehydrosilychristin-19-O-sulfate showed the strongest inhibitory effect on CYP3A4. Based on these observations, the simultaneous administration of high dose silymarin with medications should be carefully considered, because milk thistle flavonolignans and/or their sulfate metabolites may interfere with drug therapy.