Zearalenones

The intramolecular coupling of organostannanes is applied to macrolide synthesis. In the zearalenone synthesis, no cyclization was observed between arylstannane and alkenyl iodide. However, intramolecular coupling take.s place between the alkenylstannane and aryl iodide in 706. A similar cyclization is possible by the reaction of the alkenylstannane 707 with enol triflate[579]. The coupling was applied to the preparation of the bicyclic 1,3-diene system 708[580]. 

Increased hormonal levels have resulted in better mminant animal performance. Fstrogen-containing compounds, eg, zearalenone [17924-92-4], 18 22 5 available to improve growth and feed efficiency. These estrogens are given as ear implants. Melengestrol acetate [2919-66-6] (MGA),... 

Produced by fungi which can contaminate crops. Some, such as zearalenone, are oestrogenic DDT, lindane and beta-HCH are common, persistent environmental pollutants Widespread, persistent environmental pollutants... 

Farmed animals tend to be subjected to compounds that can be classified more easily as drugs. In some cases, animals may encounter compounds in nature that have considerable limitations in inclusion in the diets of farmed animals. An example is the inclusion of zearalenone (Figure 1) and its derivatives in animal diets these have anabolic and oestrogenic properties " and are permitted to be used in some areas of the world but are prohibited from use in others, such as European Union countries. Thus this compound and its reduced isomers (zearalenols, zeranols) improve growth rates in animals but can cause reproductive problems, especially in pigs. Ralgro, which is a commercially prepared derivative of zearalenone, is used as an ear implant in beef cattle as a growth promoter in... 

Ochratoxin A, citrinin, penicillic acid, sterigmatocystine, zearalenone... 

After the dipped or sprayed chromatogram has been dried in a stream of cold air long-wave UV light (2 = 365 nm) reveals fluorescent yellow zones (flavonoids). Sterigmatocystine, which can be detected without derivatization on account of its red intrinsic fluorescence (detection limit 0.5 pg), also fluoresces pale yellow after being heated to 80°C [9] or 100°C [13] for 10 min on the other hand, citrinine, zearalenone and vomitoxin fluoresce blue. 

An intramolecular variant of the Stille coupling is suitable for the construction of macrocycles. An example is the ring-closing step to form a 14-membered lactone ring 8 in a synthesis of zearalenone as reported by Stille et al. ... 

Z factor, 154-155 Z values, 156-158 Zearalenone, 186 Zero-tolerance toxicides, 169 Zofenopril, 163f Zofran, 154f... 

An intramolecular palladium(o)-catalyzed cross-coupling of an aryl iodide with a trans vinylstannane is the penultimate maneuver in the Stille-Hegedus total synthesis of (S)-zearalenone (142) (see Scheme 38).59 In the event, exposure of compound 140 to Pd(PPh3)4 catalyst on a 20% cross-linked polystyrene support in refluxing toluene brings about the desired macrocyclization, affording the 14-membered macrolide 141 in 54% yield. Acid-induced hydrolysis of the two methoxyethoxymethyl (MEM) ethers completes the total synthesis of 142. 

Mayr U, Butsch A and Schneider S. 1992. Validation of two in vitro test systems for estrogenic activities with zearalenone, phytoestrogens and cereal extracts. Toxicology 74 135-149. 

Fusarium species Trichothecenes Zearalenone Fumonisins Moniliformin... 

Zearalenone (ZEA) is synthesised by many Fusarium species, which also produce DON, and is found worldwide in maize and maize products. Young sows seem to be the most susceptible animals and may show symptoms of hyperoestrogenism even with low ZEA intakes (0.06 mg/kg body weight intake). In contrast, 300 ppm are reported to be tolerated by hens and up to 2000 ppm by young heifers (Fink-Gremmels, 2005a). 

Deoxynivalenol Nivalenol Zearalenone T-2 toxin Moniliformin Ochratoxin A Aflatoxins... 

Table 17.4 Regulations for deoxynivalenol (DON) and zearalenone (ZEA) in the European Union according to the Commission Regulation (EC) No 856/2005 of 6 June 2005 (EC, 2005d)...

Reutter M (1999), Zearalenon und Deoxynivalenol in Getreide und Futtermitteln Schleswig -Holsteins Untersuchungen aus dem Erntejahr 1998 , Proceedings 21st Mykotoxin-Workshop, Jena, 5-9. 

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