Antibacterial significance

Table 1. Commercially Significant Quinolone Antibacterial Agents...

When ofloxacin was first introduced it was made available as the racemate. Later the optical isomers were prepared and it was found that the (3)-enantiomer, DR 3355 (6b), was substantially more active (8—128-fold) than the (R)-isomer against a broad range of bacteria (47—50). This chiral preference is not unique to ofloxacin and has been demonstrated in other quinolones as well (51,52). This significant finding has already had an impact on the design of new quinolone antibacterials still in development (53). 

The addition of a 3-hydroxypropyl group to the 7 -position of fortimicin A caused a significant reduction in antibacterial activity (237). 

As can be seen from Table 3, only modifications at the 6/3-amino groups have been successful in producing penicillins of medical significance up to this time. Several reviews have dealt with the structure-activity relationship in this area in considerable detail B-80MI51102, B-77MI51106, B-75MI51102) and should be consulted for the actual effects of structural modification on antibacterial activity. 

Neurotropic and antistress properties of 2,4-dimethylpyrido[l, 2-u]pyr-imidinium perchlorate were compared with those of piracetam (95MI7). AH-Pyrido[l,2-u]pyrimidin-4-one binds selectively to rat A3 receptors with a A", value of 48/xM. No affinities were observed to rat Ai and A2 receptors (96MI17). 4-Oxo-4//-pyrido[l,2-u]pyrimidine-3-carboxylic acid and -3-carbonitrile did not exhibit significant antibacterial activities (97MI6). 

Surfactants (detergents) also help clean the teeth they provide a foam that helps to carry away debris. Moreover, lauryl sulfates have significant antibacterial properties, and they can penetrate and dissolve plaque. 

Not only eukaryotic cells but also bacteria have successfully been targeted by PNA anhsense strategies. Thus it has been shown that PNA complementary to ribosomal RNA or mRNA encoding an essential fatty acid biosynthesis protein, effectively kills E. coli. Furthermore, it has been shown that PNA directed to the start codon of the y -lactamase gene re-sensitized otherwise resistant E. coli to the antibiohc ampiciUin [64—66]. Conjugating a simple transporter peptide to the PNA increased the potency significantly, and an even more potent antibacterial PNA... 

Boyd DB. Beta-lactam antibacterial agents Computational chemistry investigations. In Greenberg A, Breneman CM, Liebman JF, editors. The amide linkage Structural significance in chemistry, biochemistry, and materials science. New York Wiley, 2000. p. 337-75. 

Phenol no longer plays any significant role as an antibacterial agent. It is of historical interest, since it was introduced by Lister in 1867 as an antiseptic and has been used as a standard for comparison with other disinfectants, which are then given a phenol coefficient in tests such as the Rideal-Walker test. 

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