Antibiotics chemical structures

Fig. 4.11 Chemical structures of antibiotics. Chemical structures of nucleosides are provided in the top row for comparison with the antibiotics shown in the second row. The third row shows chemical structures of antibiotics that only weakly resemble the nucleosides to which they have been compared.

Fig. 3. Aminoglycoside antibiotics chemical structures of streptomycin (/) and dihydrostreptomycin (//). Ring = streptidine ring 5=streptose ring C=iV-methyl-L-glucosa-mine ring D = streptobiosamine...

Pascard, C., a. Ducruix, J. Lunel, and T. Prange Highly Modified Cysteine-Containing Antibiotics. Chemical Structure and Configuration of Nosiheptide. J. Amer. Chem. Soc. 99,6418 (1977). 

Therapeutic Function Antibiotic Chemical Name Oleandomycin see Structural Formula Common Name Troleandomycin Structural Formula ... 

Chemical Name Complex antibiotic see structural formula Common Name —... 

The first of the antibiotics that found practical use as a therapeutic was penicillin. The success of penicillin initiated a vast screening process all over the world, which resulted in the isolation of a large number of antibiotic substances from various natural sources. Many of these compounds were produced by micro-organisms and prove to be lethal for other micro-organisms. Many of these compounds were also very toxic to humans and could not be used therapeutically. Nevertheless a large number of classes of useful compounds were produced. The chemical structures of members of some of the most important classes are shown in Figure 6.1. 

Figure 6.1 The chemical structure of some members of the important classes of antibiotics.

Thienamycin (Fig. 5.5E) is a broad-spectrum /3-lactam antibiotic with high /3-lactamase resistance. Unfortunately, it is chemically unstable, although the TV-formimidoyl derivative, imipenem, overcomes this defect. Imipenem (Fig. 5.5E) is stable to most/3-lactamases but it readily hydrolysed by kidney dehydropeptidase and is administered with a dehydropeptidase inhibitor, cilastatin. Meropenem, which has yet to be marketed, is more stable than imipenem to this enzyme and may thus be administered without cilastatin. Its chemical structure is depicted in Fig. 5.5F. 

Antibiotics may be classified by chemical structure. Erythromycin, chloramphenicol, ampicillin, cefpodoxime proxetil, and doxycycline hydrochloride are antibiotics whose primary structures differ from each other (Fig. 19). Figure 20 shows potential oscillation across the octanol membrane in the presence of erythromycin at various concentrations [23]. Due to the low solubility of antibiotics in water, 1% ethanol was added to phase wl in all cases. Antibiotics were noted to shift iiB,sDS lo more positive values. Other potentials were virtually unaffected by the antibiotics. On oscillatory and induction periods, there were antibiotic effects but reproducibility was poor. Detailed study was then made of iiB,sDS- Figure 21 (a)-(d) shows potential oscillation in the presence of chloramphenicol, ampicillin, cefpodoxime proxetil, and doxycycline hydrochloride [21,23]. Fb.sds differed according to the antibiotic in phase wl and shifted to more positive values with concentration. No clear relationship between activity and oscillation mode due to complexity of the antibacterium mechanism could be discovered but at least it was shown possible to recognize or determine antibiotics based on potential oscillation measurement. 

N-4 position and a substituted ring at the N-l position. Because of this different chemical structure, cross-allergenicity with the other sulfonamides may not occur. However, because this has not been well studied, if a patient has a reaction to a sulfonamide antibiotic, whether or not he or she will have a reaction to these other sulfonamides remains controversial. Predisposition to allergic reactions is a more likely reason than cross-reactivity between these differing molecules.14 The sulfonamide antibiotics are significant because they account for the largest percentage of antibiotic-induced toxic epidermal necrolysis and Stevens-Johnson syndrome cases.15... 

Table 1 Summarized table with the more important PPCPs divided into antibiotics, steroid hormones, and other drugs. Their generic chemical structures and the use or origin are shown. Some reported data regarding their environmental occurrence and the more probable environmental fate are also given... 

Fig. 1 Chemical structures of some of the most important antibiotics used nowadays divided into the most representative families fluoroquinolones, sulfonamides, penicillins, macrolides, and tetracyclines. Another important antibiotic, chloramphenicol, is also shown...

Structural steels, tellurium in, 24 425 Structure(s), see also Chain structure Chemical structures Cocontinuous structures Controlled structure Crystal structure Molecular structure Morphology Phase structure of carbon fibers, 26 737-739 detersive systems for, 8 413t HDPE, 20 157-162 LLDPE, 20 182-184, 203-205 polyesterether elastomer, 20 72-73 polyester fiber, 20 21 polyether antibiotics, 20 137-139 polyimide, 20 276-278 polymer, 20 395-405 protein, 20 449 PTT, 20 68t... 

The first consideration when investigating HPLC method development protocols is the chemical structure of the analyte, in particular, the presence of functional groups capable of interacting with the stationary phase and containing or in the vicinity of the stereogenic elements [79]. Since the natural target of macrocyclic antibiotics is the A-acyl-D-alanyl-D-alanine terminus (see Section 2.1), the early choice of suitable substrates for this kind of CSPs was that of amino acids [45]. However, it turned out that the macrocyclic CSPs were very successful not only in amino acids enantioresolution, but also in the separation of a wide variety of different structures. 

Different classifications for the chiral CSPs have been described. They are based on the chemical structure of the chiral selectors and on the chiral recognition mechanism involved. In this chapter we will use a classification based mainly on the chemical structure of the selectors. The selectors are classified in three groups (i) CSPs with low-molecular-weight selectors, such as Pirkle type CSPs, ionic and ligand exchange CSPs, (ii) CSPs with macrocyclic selectors, such as CDs, crown-ethers and macrocyclic antibiotics, and (iii) CSPs with macromolecular selectors, such as polysaccharides, synthetic polymers, molecular imprinted polymers and proteins. These different types of CSPs, frequently used for the analysis of chiral pharmaceuticals, are discussed in more detail later. 

Figure 11.1. Representative chemical structures of aminoglycoside antibiotics.

Vancomycin Vancomycin (32.7.2) was isolated in 1956 from the products of the functional activity of actinomycetes Streptomyces orientalis (cnrrently Nocardia orientalis). Based on its chemical structure and contents, vancomycin is classified as a glycopeptide antibiotic. Its molecular mass is significantly more than practically any other used antibiotics [325-330]. 

Antibiotics are generally defined as low molecular mass microbial secondary metabolites which, at low concentrations, inhibit the growth of other microorganisms. To date, well in excess of 10 000 antibiotic substances have been isolated and characterized. Overall, antibiotics are a chemically heterogeneous group of molecules, although (as described later) many can be classified into different families based upon similarity of chemical structure. 

When grouped on the basis of similarities in their chemical structure, most antibiotics fall into the categories listed in Table 1.17. S-Lactams, which include penicillins and cephalosporins, exhibit a characteristic /i-lactam core ring structure (a four-atom cyclic amide) (Figure 1.14). They induce their bacteriocidal activity by inhibiting the synthesis of peptidoglycan, an essential component of the bacterial cell wall. 

Figure 1.16. Chemical structure of the antibiotic tetracycline. Other members of the tetracycline family (see also Table 1.18) also display this characteristic 4-ring structure...

Figure 1.17. Chemical structure of chloramphenicol, the first broad-spectrum antibiotic to gain clinical...

The penicillins are a large group of bactericidal compounds. They can be subdivided and classified by their chemical structure and spectrum of activity. The structure common to all penicillins is a (3-lactam ring fused with a thiazolidine nucleus (Fig. 45.1).The antimicrobial activity of penicillin resides in the (3-lactam ring. Splitting of the (3-lactam ring by either acid hydrolysis or (3-lactamases results in the formation of penicilloic acid, a product without antibiotic activity. Addition of various side chains (R) to the basic penicillin molecule... 

Loracarbef Lorabid) is a synthetic p-lactam antibiotic of the carbacephem class. The chemical structure of loracarbef is similar to that of cefaclor. Selected pharmacokinetic information appears in Table 45.2. Lora-carbef s spectrum of antibacterial activity resembles those of the second-generation cephalosporins. Comparative clinical trials reveal similar outcomes in patients treated with cefaclor, cefprozil, and loracarbef. 

Fig. 5.4 Chemical structures of commonly used polyether ionophore antibiotics.

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