Antibiotics, derived from

Oligosaccharides also occur widely as components (via glycosidic bonds) of antibiotics derived from various sources. Figure 7.20 shows the structures of a few representative carbohydrate-containing antibiotics. Some of these antibiotics also show antitumor activity. One of the most important of this type is bleomycin A2, which is used clinically against certain tumors. 

A microwave assisted Comforth rearrangement of oxazole-4-carboxamides 106 efficiently afforded 5-aminooxazole-4-carboxylates 107. This procedure was applied to the formal synthesis of a natural antibiotic derived from pseudomonic acid <06TL4698>. 

Tetracyclines are a group of antibiotics derived from bacteria. Chlortet-racycline was isolated from Streptomyces aureofaciens and oxytetracycline from Streptomyces rimosus. Tetracychnes act by binding to receptors on the bacterial ribosome and inhibit bacterial protein synthesis. 

Nicas, T.I. et al. Semisynthetic glycopeptide antibiotics derived from LY264826 active against vancomycin-resistant enterococci, Antimicrob. Agents Chemother., 40, 2194, 1996. 

During the development of a sterile formulation of pirlimycin, a semisynthetic, veterinary lincosaminide antibiotic derived from lincomycin 4, three lots of material were subjected to thermal stress at 40°C for a period of 4 months, which led to the observation of a previously unreported degradant present at 0.2% [69]. 

Pharmacology Rifabutin, an antimycobacterial agent, is a semisynthetic ansamycin antibiotic derived from rifamycin S. It is not known whether rifabutin inhibits DNA-dependent RNA polymerase in Mycobacterium avium or in Mycobacterium... 

The cephalosporins are semisynthetic antibiotics derived from products of various microorganisms, including Cephalosporium and Streptomyces. All cephalosporins... 

Although it is not chemically related to cyclosporine, tacrolimus (6.7) has a similar mechanism of action. Tacrolimus is an immunosuppressant macrolide antibiotic derived from Streptomyces tsukubaenis. Like cyclosporine, tacrolimus inhibits the same cytoplasmic phosphatase, calcineurin, which catalyzes the activation of a T-cell-specific transcription factor (NF-AT) involved in the biosyntheses of interleukins such as IL-2. Sirolimus (6.8) is a natural product produced by Streptomyces hydroscopicus, it blocks the ability of T cells to respond to cytokines. 

Rifamycin SV is a semi-synthetic antibiotic derived from rifamycin B, a substance produced during growth of certain strains of Streptomyces mediterranei. 

New /3-lactam antibiotics derived from natural and synthetic sources 89PHA177. 

Niphimycin, an antimycotic antibiotic derived from Actinomyces hygroscopicus, is effective against both der-matomycosis and onychomycosis, with a 16-26% success rate in the latter. Tolerance is reportedly good, but there is a notable lack of recent data (SEDA-12, 236). 

Kirrstetter R, Durckheimer W. Development of new betalactam antibiotics derived from natural and synthetic sources. Pharmazie 1989 44(3) 177-85. 

Rifamycin SV (rINN), a semisynthetic macrocyclic antibiotic derived from natural rifamycin B, has been used in the therapy of tuberculosis and in some European countries as a topical antibiotic. Anaphylaxis has been reported after systemic administration, and rarely after topical application. 

A consequence of the development of the large number of cephalosporins is that the molecular structures have become more and more complex. Alterations in the cephalosporin molecule have resulted in differences between cephalosporins in spectrum of activity, protein binding, peak serum level, serum half-life, route of excretion, cerebrospinal fluid levels and toxicity. Cephalosporins are semi-synthetic antibiotics derived from 7-aminocephalosporanic acid, which is also called the cephalosporin nucleus. The cephem ring ( nucleus") is composed of a (3-lactam ring fused with a dihydrothiazine ring (Figure 1). 

Atkinson RM, Curie LP, Prat PAH, Sharpe HM,Tomich EG. Acute toxicity of cephaloridine, an antibiotic derived from cephalosporin C.Toxicol AppI Pharmacol 1966 8(3) 398-406. 

Quinolone and fluoroquinolone antibiotics are a group of highly-potent, synthetic antibiotics, derived from 3-quinolone carboxylic acid They are used as broad-spectrum antibiotics in the treatment of both human and veterinary diseases. 

CAS 3930-19-6. C23I I2 ,N4()8. An antibiotic derived from Streptomyces flocculus. Dark-brown, rectangular crystals. 

Figure 6. Examples of antibiotics derived from cephalosporin...

Tetracyclines are a group of antibiotics derived from bacteria. Chlortetracycline was isolated from Streptomyces aureofaciens and... 

Tilmicosin, Figure 1, is a new semisynthetic antibiotic derived from the macrolide antibiotic tylosin. The synthesis and antibacterial activity of tilmicosin have been described by Debono, et al. and Kirst, et al. (/-4). Tilmicosin has in vitro activity against a variety of Gram positive and Gram negative bacteria, as well as mycoplasma species. It is effective for treatment of bovine respiratory disease caused by Pasteurella haemolytica when administered as a single subcutaneous injection (5, 6). This paper describes the excretion, tissue residue pattern, and metabolism of tilmicosin when injected into cattle, and also gives comparative metabolism data from rats which were dosed orally. 

Streptozocin, a naturally occurring nitrosourea antibiotic derived from Streptomyces acromogenes (500 mg/m2 fV for 5 consecutive days q 4 to 6 weeks until maximum benefit or toxicity is observed), is indicated in metastatic islet cell carcinoma of the pancreas. Streptozocin is nephrotoxic causing azotemia, glycosuria and renal tubular acidosis, and mild proteinuria. 

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