Synthetic antimicrobials

Originally, the term antibiotics referred to substances produced by microorganisms that suppressed the growth of other organisms. Today, the term antibiotics often includes synthetic antimicrobial agents. 

Oxazolidinones are a new class of synthetic antimicrobial agents, which have activity against many important pathogens, including methicillin-resistant Staphylococcus aureus and others. Oxazolidinones (e.g. linezolid or eperezolid) inhibit bacterial protein synthesis by inhibiting the formation of the 70S initiation complex by binding to the 50S ribosomal subunit close to the interface with the 3OS subunit. 

Quinoxaline-1,4-dioxides are synthetic antimicrobial agents the best-known members are carbadox and olaquindox. Both compounds are rapidly metabolized to monoxy- and desoxy- compounds. The final product from carbadox and the one most often determined, mainly in liver (target tissue), is quinoxaline-2-carboxylic acid. Carbadox and olaquindox are light-sensitive compounds and sample manipulations should be performed only under the minimum of indirect incandescent illumination. Carbadox and desoxycarbadox are insoluble in water but are soluble in chloroform and methanol, while olaquindox is slightly soluble in water and some organic solvents. The solubility, however, of quinoxaline-2-carboxylic acid can be easily monitored by adjusting the pH because it is a strong carboxylic acid (pK 2.88). 

Humans cannot synthesise folic acid. Many bacteria, however, synthesise it from PABA this bacteria-specific pathway provides a target for synthetic antimicrobial agents like the sulphonamides and trimethoprim (Figure 20.4). Sulphonamides inhibit dihydropteroate syn-... 

The oxazolidinones are a new class of synthetic antimicrobial agents. Produced in 1987, they were found to be active in vitro against antibiotic-susceptible and -resistant cocci and did not demonstrate cross-resistance with any other antibiotics. 

Alvarez-Bravo, J., Kurata, S. and Natori, S. (1994) Novel synthetic antimicrobial peptides... 

Nakajima, Y., Alvarez-Bravo, J., Cho, J.-H., Homma, K.-I., Kanegasaki, S. and Natori, S. (1997) Chemotherapeutic activity of synthetic antimicrobial peptides correlation between chemotherapeutic activity and neutrophil-activating activity. FEBS Lett. 415, 64-66. 

Linezolid (Zyvox) is a synthetic antimicrobial agent of the oxazolidinone class. 

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