Neomycin aminoglycoside antibiotics

Aminoglycosides. Antibiotics ia the amiaoglycoside group characteristically contain amino sugars and deoxystreptamiae or streptamiae. This family of antibiotics has frequentiy been referred to as aminocyclitol amiaoglycosides. Representative members are streptomycia, neomycin, kanamycia, gentamicin, tobramycia, and amikacin. These antibiotics all inhibit proteia biosynthesis. 

Development of resistance to rifaximin is primarily due to a chromosomal one-step alteration in the drug target, DNA-dependent RNA polymerase. This differs from the plasmid-mediated resistance commonly acquired by bacteria to aminoglycoside antibiotics such as neomycin... 

Commercial neomycin is a complex mixture of aminoglycoside antibiotics originally isolated from a culture of Stn.tptomyc.zi, ( n.adiaz by Waksman and his co-workers in 1949. The principle components of the mixture are neomycin B(I) and neomycin C(II) together with a small quantity of neaminel, a degradation product of neomycin formerly known as neomycin A. Table 1 shows the content variability of neomycin B and C and neamine in commercial samples of neomycin as reported in the literature. Neomycins LP-A, LP-B and LP-C which chemically are the mono N-acetyl derivatives of neomycins A, B and C may also be present in small amounts. Several other minor components have recently been identified as paromamine, paromomycin I and paromomycin II. (Also known as neomycins D, E and F respectively). 

During a study of the physicochemical properties of some aminoglycoside antibiotics Kuzyaeval- - determined the static and dynamic exchange capacities of neomycin on the cation exchange resin KB-4P-2(a phenoxyacetic ac. d-f ormaldehyde resin) using the resin in the Na form. 

Neomycin has been separated from mixtures of other aminoglycoside antibiotics containing the 2-deoxystreptamine moiety as both the pertrimethylsilyl derivative and the N-trifluoro-acetyl pertrimethylsilyl derivative using a column of 0.75% 0V-1 on Gas Chrom q240. The procedure may be used to estimate the number of sugar moieties bound in the antibiotic as a close relationship exists between the number of rings and the retention time. 

Likewise, the antoconvulsant phenytoin sodium and neomycin—an aminoglycoside antibiotic also decrease the cholesterol levels, and... 

Newer examples of aminoglycoside antibiotics include amikacin, neomycin (Neosporin, Cortisporin), and tobramycin (TOBI, TobraDex). Injectable tobramycin is used in the treatment of serious infections at many body sites. It has also been formulated in an inhalable dosage form that has a very specific use to treat cystic fibrosis patients having Pseudomonas aeruginosa lung infections. In the form suitable for inhalation by the patient, it delivers the antibiotic directly to the site of infection. 

Although a number of chromatographic methods have been reported for determinations of aminoglycoside antibiotics in blood serum and urine, the application of chromatographic methods to residue analysis has been very limited. Shaikh et al (93) recently described an HPLC method for neomycin in animal tissue, and Lachatre et al (94) described a method for nine aminoglycosides in plasma, urine, and renal cortex tissue. Both procedures use post column derivatization with a-pthalaldehyde and fluorescence detection. 

AND ANTIBACTERIAL ACTIVITY OF KANAMYCIN AND NEOMYCIN CLASS AMINOGLYCOSIDE ANTIBIOTICS... 

Attaching fnnctionalities at the N-1 position of the 2-deoxystreptamine among kanamycin or neomycin class antibiotics, is one of the other most effective methods of reviving the activity against aminoglycoside resistant bacteria. This strategy has led to the development of semisynthetic amikacin that has an (5 )-4-amino-2-hydroxybutyryl (AHB) group at N-1 position. 

Neomycin Neomycin is a complex of aminoglycoside antibiotics (neomycin A, neomycin B, and neomycin C) that is synthesized by the actinomycete Streptomyces fradiae. [26-30]. For example, neomycin B is 0-2,6-diamino-2,6-didesoxy-a-D-glucopyranosyl-(l )-0-[0-2,6-diamino-2,6-didesoxy-)3-L-idopyranosyl(l—>3)-)3-D-ribofuranosyl-(l— 5)]-2-desoxy-D-streptamine (20.3.1). 

Fourmy D, Recht Ml, Puglisi JD (1998) Binding of neomycin-class aminoglycoside antibiotics to the A-site of 16S rRNA. J Mol Biol 277 347-362... 

The glycoside/aminoglycoside antibiotics, like the macrolides, exert a bacteriostatic effect due to selective inhibition of bacterial protein synthesis, with the exception of novobiocin (26). The compounds neomycin (27), spectinomycin (28) and streptomycin (29) bind selectively to the smaller bacterial 30S ribosomal subunit, whilst lincomycin (30) binds to the larger 50S ribosomal subunit (cf. macrolides). Apramycin (31) has ribosomal binding properties, but the exact site is uncertain (B-81MI10802). Novobiocin (26) can inhibit nucleic acid synthesis, and also complexes magnesium ion, which is essential for cell wall stability. 

The aminoglycoside antibiotics streptomycin (Box 20-B),c d u v the neomycins,w paromomycin (see drawing below),c x z gentamycin,aa and kanamycin have one structural unit in common. They often bind to 16S ribosomal RNA in the decoding center. 

The phosphate backbone of both DNA and RNA provides a negatively charged template for attracting positively charged species. Drugs that commonly exploit this interaction are the aminoglycoside antibiotics. Examples include neomycin B (6.20) and kanamycin A (6.21) (Figure 6.12). This class of compounds binds rRNA in bacteria to interfere with translation of mRNA into functional proteins. 

Tsuji and Robertson analysed aminoglycoside antibiotics by GC of kanamycin, paromomycin and neomycin [525] and tetracyclines [526] after their silylation with a BSA-TMCS mixture in pyridine (1 1 2, v/v) or with commercially available Tri Sil Z reagent. The reaction was performed at room temperature for 24 h or at 75°C for 45 min. Good results with respect to peak symmetry and the separation of various compounds were obtained on silicone stationary phases at 260°C. 

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