Aminoglycosides chemical structures

Figure 11.1. Representative chemical structures of aminoglycoside antibiotics.

Fig. 3.1 Chemical structures of commonly used aminoglycosides and aminocyclitols.

Figure 29.9. Chemical structures of several aminoglycoside antibiotics.

The aminoglycoside antibiotics include streptomycin, neomycin, gentamicin, amikacin, tobramycin and kanamycin. They have a chemical structure of amino sugars joined by a glycoside... 

Chemical Structure Aminoglycosides are antimicrobial agents with dissimilar structures it is impossible to represent aminoglycosides with a single general structure. The following is the structure of streptomycin ... 

Further antibiotics, mainly derived from actinomycetes, are used for special applications in human and veterinary medicine [20]. These compounds have numerous chemical structures. The macrolides, tetracyclines, aminoglycosides, glycopeptides, and ansamycins for instance are used in antibacterial treatment whereas the anthracyclines reached the market to supplement anticancer chemotherapy. The fairly toxic polyether-type antibiotics are preferably used as anticoccidial agents. Due to the dramatically increasing resistance of clinical important bacterial strains new targets for the discovery of novel types of antibacterial agents are urgently needed. 

Figure 1 Chemical structure of the common 4,6- and 4,5-substituted deoxystreptamine aminoglycosides ribostamycin and kanamycin A.

Aminoglycosidic antibioties inhibit protein synthesis on bacterial ribosomes, but the primary sites that are subject to the action of each of these antibiotics are different and are now under study. As yet, there is no information about the chemical structure of the primary sites, and... 

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...

Fig. 4. Chemical structures of aminoglycoside antibiotics containing 4,5- (a) or 4,6- (b) substituted deoxystreptamine. Rings yt,Z) = 2,6-diaminoglucose ring /i =6-aminoglucose ring 5=deoxystreptamine ring C=D-ribose ring C =3-aminoglucose...

Nowadays, antibiotics are primarily classified according to the mechanism of their action, with similarity of chemical structure as a secondary factor. Penicillin and its derivatives inhibit the formation of bacterial cell walls (Fig. 3.38). Cephalosporins have the same active mechanism. Other compounds are taken up into bacterial DNA to form unstable molecules (quinolones, metronidazole) or inhibit peptide synthesis (tetracychnes, aminoglycosides, macrolides). Some antibiotics (e.g. glycopeptides) exert a complex effect. 

Although a large variety of compounds can reduce tris(2,2 -bipyridyl)ruthenium(III), only certain species (e.g., aliphatic amines, amino acids, NADH, some alkaloids, aminoglycoside or tetracycline antibiotics, and the oxalate ion) will produce the characteristic orange luminescence with this reagent. Subtle differences in chemical structure can have a dramatic effect on chemiluminescence intensity. This is exemplified by the determination of the papaver alkaloid codeine (11) compared to structurally similar morphine (12). At pH 6.8, codeine can be determined down to a concentration of 10 mol 1 whereas morphine produces a chemiluminescent response equivalent to that of the blank. In many applications this degree of selectivity is most desirable. 

The different 3D-shapes adopted by aminoglycosides in the RNA- and enzyme-bound states suggest a possible structure-based chemical strategy to obtain antibiotics with better activity against resistant bacteria. Assiun-ing that, in these cases, some degree of conformational distortion of the substrates is required for enzymatic activity, it should be possible to design a conformationally locked oHgosaccharide that still retains antibiotic activity, but that is not susceptible to enzymatic inactivation (Fig. 8) [41]. 

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