Eperezolid is an antibiotic agent developed for the treatment of a wide range of bacterial infections. The drug exerts its action by binding to 50 S ribosome subunit causing the inhibition of protein synthesis in bacterias. Eperezolid was tested in preclinical in vivo models of different becterial diseases in which it was shown to be active.

Puromycin dihydrochloride belongs to the aminonucleoside family of antibiotics and is isolated from Streptomyces alboniger. Since the partial structure of this antibiotic showed it to be a purine derivative, puromycin was assigned as its generic name. Puromycin is a broad spectrum antibiotic and antibacterial agent. It is active against Gram-positive microorganisms, less active against acid-fast bacilli, and weakly active against Gram-negative microorganisms. It acts very quickly and can kill 99% of the cells within 2 days. It also exhibits antitumor activity in studies on brain tumor cells. Puromycin is a protein synthesis inhibitor that causes premature chain termination by acting as an analog of the 3’-terminal end of aminoacyl-tRNA. It has been used to study transcriptional regulatory mechanisms that control the sequential and coordinate expression of genes during cell differentiation.

Azaerythromycin A is a novel intermediate of Azithromycin which acts as an antibiotic. Azithromycin binds to the 50S subunit of the bacterial ribosome, and thus inhibits translation of mRNA.

Blasticidin S is a metabolite of Streptomyces griseochromogenes and was formerly used in practice as a fungicide against a phytopathogenic fungus, Pyricularia oryzae. Blasticidin S inhibits protein synthesis of both prokaryotic and eukaryotic organisms by interacting with their ribosomes. Blasticidin S, a protein synthesis inhibitor, inhibits aflatoxin production of Aspergillus flavus without affecting fungal growth. It has been demonstrated that blasticidin S also exhibits antibacterial activity, toxicity to mammalians and tumor-inhibitory activity.

Hygromycin A, an antibiotic produced by Streptomyces hiygroscopicus, is active against gram-positive bacteria including mycobacteria and actinomycetes, as well as against endomoeba, leptospira and pleuro- pneumonia-like organisms. Hygromycin A binds strongly to bacterial ribosomes and inhibits the ribosomal peptidyl transferase activity. The antibiotic binds to the ribosome in a distinct but overlapping manner with other antibiotics and offers a different template for generation of new agents effective against multidrug-resistant pathogens.

French pharmaceutical company Hoechst Marion Roussel (later Sanofi-Aventis) began phase II/III clinical trials of telithromycin (HMR-3647) in 1998. Telithromycin was approved by the European Commission in July 2001 and subsequently went on sale in October 2001. In the US, telithromycin received U.S. Food and Drug Administration (FDA) approval on April 1, 2004 Telithromycin is the first ketolide antibiotic to enter clinical use and is sold under the brand name of Ketek. After significant controversy regarding safety and research fraud, the US Food and Drug Administration sharply curtailed the approved uses of the drug in 2007. Telithromycin is a semi-synthetic erythromycin derivative. It is created by substituting a ketogroup for the cladinose sugar and adding a carbamate ring in the lactone ring. An alkyl-aryl moiety is attached to this carbamate ring. Furthermore, the carbon at position 6 has been methylated, as is the case in clarithromycin, to achieve better acid-stability. For the treatment of Pneumococcal infection, acute sinusitis, acute bacterial tonsillitis, acute bronchitis and bronchiolitis, lower respiratory tract infection and lobar (pneumococcal) pneumonia. KETEK tablets contain telithromycin, a semisynthetic antibacterial in the ketolide class for oral administration. Telithromycin blocks protein synthesis by binding to domains II and V of 23S rRNA of the 50S ribosomal subunit. By binding at domain II, telithromycin retains activity against gram-positive cocci (e.g., Streptococcus pneumoniae) in the presence of resistance mediated by methylases (erm genes) that alter the domain V binding site of telithromycin. Telithromycin may also inhibit the assembly of nascent ribosomal units.

Dirithromycin (Dynabac) is a macrolide glycopeptide antibiotic used to treat different types of bacterial infections, such as bronchitis, pneumonia, tonsillitis, skin infections. Dirithromycin is a semi-synthetic derivative of erythromycin - the hemi-aminal resulting from the condensation of (9S)-erythromycyclamine with 2-(2-methoxyethoxy) acetaldehyde. Being unstable under both acidic and alkaline conditions, dirithromycin functions as a more lipid-soluble prodrug for (9S)-erythromycyclamine. Erythromycylamine exerts its activity by binding to the 50S ribosomal subunits of susceptible mircoorganisms resulting in inhibition of protein synthesis. Dirithromycin has been shown to be active against most strains of the following microorganisms both in vitro and in clinical infections: Staphylococcus aureus (methicillin-susceptible strains only), Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Legionella pneumophila, Moraxella catarrhalis, and Mycoplasma pneumoniae. Dirithromycin showed better activity in vitro against Campylobacter jejuni and Borrelia burgdorferi than erythromycin or clarithromycin but in general demonstrated less activity than erythromycin, clarithromycin, or azithromycin against a majority of microorganisms. The pharmacokinetic profile of dirithromycin has advantages over other microlides of once-daily dosing and high and prolonged tissue concentrations but adverse effect profiles similar to those of the other macrolides, with reported problems most often related to the gastrointestinal tract.

Sisomicin is a new broad-spectrum aminoglycoside most closely related structurally to gentamicin C1a. In vitro and in experimental infections, sisomicin has been found to be more potent than or nearly as potent as the most active of the other available aminoglycosides. Although susceptible to many (but not all) aminoglycoside-inactivating enzymes, sisomicin is active against many microorganisms that are resistant to other aminoglycosides by nonenzymatic mechanisms. Sisomicin has been shown to interact synergistically with various beta-lactam antibiotics against enterococci, staphylocicci, Enterobacteriaceae, and nonfermentative gram-negative bacilli. The pharmacokinetics and toxicity of sisomicin in humans appear to be similar to those of gentamicin, despite earlier reports of greater acute toxicity in animals. Sisomicin binds to 30s and 50s ribosomal subunits of susceptible bacteria disrupting protein synthesis, thus rendering the bacterial cell membrane defective.