Glycopeptides avoparcin

The majority of these are antibiotics and they cover a diverse group including the glycopeptide, avoparcin (95), tetracycline, macrolides, such as tylosin (23) and virginiamycin (96), as well as peptides, glycopeptides and terpenes. Antibacterials such as the quinoxaline-1,4-dioxide, carbadox (39), and nitrofurans, e.g. furazolidone (35) and nitrovin (97), are also represented. 

Avoparcin, a mixture of highly similar glycopeptides avoparcin a (83) and P (84) belongs to commercially available antibiotics used mainly in veterinary medicine. The aglycone called avoparcin 8 (85) was later isolated from the cultivation broth of Streptomycete. 

The above addresses only part of the problem. The use of antibiotics is rife in areas such as animal husbandly, agriculture, aquaculture and even in the oil industry to prevent spoilage by contaminating microorganisms. A particularly pertinent example is the use of avoparcin in animal feed for many years. Avoparcin is related to the glycopeptides... 

Non steroidal antiinflammatory drugs were among the first classes of chiral compounds investigated in the early stages of the application of macrocyclic antibiotics as chiral selectors therefore, they were screened on vancomycin [7], teicoplanin [30], ristocetin A [33] CSPs under RPmode systems, and on avoparcin CSP under NP mode systems [37]. The enantioresolution of a variety of pro fens was later reported on commercially available vancomycin CSPs [128, 168], and recently on a ME-TAG CSP [58]. Ibuprofen enantiomers were also separated on a CDP-1-containing CSP [55]. Glycopeptide A-40,926 CSP was successfully employed in the analytical and semipreparative separation of 2-arylpropionic acids [63]. 

The SARs of glycopeptide antibiotics have mostly been studied with vancomycin and teicoplanin. Some other examples also comprise the glycopeptides eremomycin, baMmycin, ristocetin, and avoparcin. The reasons for the predominance of vancomycin and teicoplanin are that, particularly vancomycin (Vancomycin, Eli Lilly and Company) and teicoplanin (Targocid, Lepetit, Italy), are industrial large-scale fermentation products, and most of these studies were performed within research programs or with the participation of researchers from Eli Lilly and Lepetit. 

There are literally hundreds of glycopeptide antibiotics, from which vancomycin, teicoplanin, and subsequently risuxretin A (for structures see Fig. 9.18) have been commercialized by Astec as Chirobiotic V, ChiiX)biotic T. and Chirobiotic R. More recently, avoparcin (see Fig. 9.18) has also been successfully applied as a chiral selector [280],... 

In addition to the vancomycin and teicoplanin CSPs, ristocetin A (Chirobiotic R) [289] and recently avoparcin [280] have been evaluated as novel chiral SOs and CSPs. It turned out that within the large family of macrocyclic antibiotics complementarity of enantioselectivity exists for different glycopeptides. As a consequence, very often it is possible to obtain a complete resolution by switching to a congeneric antibiotic CSP, if after optimization no baseline, but partial. separation can be achieved on a certain macrocyclic antibiotic type CSP (see Fig. 9.22). It can be expected that the enantioselectivity potential of closely related antibiotics will be further exploited in the future leading to an increase in the number of macrocyclic antibiotic type CSPs. 

Glycopeptide antibiotics have been found to be very effective chiral selectors in the enantiomeric separation of racemic pharmaceutical compounds. Vancomycin, ristocetin A, rifamycins, teicoplanin, kanamycin, streptomycin, and avoparcin have been added to the running buffer to obtain enantioseparation (161,203— 207). A few technical modifications, such as coated capillaries and separation conditions in the reverse polarity mode (as opposed to normal polarity mode, where the flow is from anode to cathode) were found to improve sensitivity and increase efficiency (116,208). 

Avoparcin. AV-290 C-254 CL 81.588 LL-AV290 Avotan. Animal feed glycopeptide antibiotic complex produced by Streptomyces candidus. Prodn M. P. 

The glycopeptide antibiotics include avoparcin, teicoplanin, and vancomycin. Avoparcin is produced by Amycolatopsis coloradensis, while teicoplanin is a mixture of six closely related compounds produced by Streptococcus teichomyetius. Vancomycin is produced by Streptococcus orientalis. 

Figure 4.16 Chemical structures of the macrocyclic glycopeptide antibiotics (a) vancomycin, (b) teicoplanin, (c) avoparcin, (d) ristocetin A, that have been used as chiral selectors in CSPs for HPLC. Reproduced from Ward and Farris, J. Chromatogr. A 906 (2001), copyright (2001), with permission from Elsevier.

The use of the glycopeptide avopatcin at low levels as a growth promotant in livestock feed in Europe has afforded speculation that resistant enterococci originated in poultry. Although recent studies have demonstrated VaiV resistant isolates in (arm animals (78,79), especially poultry receiving avoparcin (80), there is little evidence from... 

Degradation of the avoparcin complex, a glycopeptide antibiotic mixture related to vancomycin and ristocetin, has yielded a variety... 

This chapter will focus on chiral recognition mechanisms and molecular interactions. The commercialized macrocyclic glycopeptides ristocetin, R, vancomycin, V, teicoplanin, T and its aglycon form, teicoplanin aglycon, TAG will be the main subject of the study since a large database is available in the literature [3-7]. However, non-commercialized avoparcin, balhimycin, and the recently introduced eremomycin macrocyclic glycopeptides [8] are also included in the study for more information on possible mechanisms. 

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