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Polyene Macrolide Antibiotic Overview

  
  
  

Macrolide Antibiotic/Overview:
It has been 60 years since the first report of erythromycin in 1952. Over the course of this 60 years the macrolide antibiotics—14- and 16-membered macrolactams—have been followed at intervals by the lincosamides, streptogramins, azalides and now the ketolides.

Erythromycin and other macrolide antibiotics bind to the 50S subunit of the bacterial ribosome and physically prevent the elongation of nascent polypeptide chains.The 50S macrolide-binding site is composed of portions of the 23S rRNA subunit, ribosomal protein L4 and ribosomal protein L22. Bacteria may acquire macrolide resistance when the genes encoding these components sustain mutations that alter the drug binding site.

Polyketides are natural products, many of which have applied potential as pharmaceuticals. Examples of such polyketides include erythromycin (anti-bacterial), Nystatin (anti-fungal), avermectin (anti-parasitic), rapamycin (immunosuppressant) and daunorubicin (anti-tumor). The Gram-positive bacteria of the genus Streptomyces are the main producers of polyketides, and the genetics and biochemistry of polyketide biosynthesis in these organisms are relatively well characterized1.

During earlier work, Shaw had discovered that LKB1 activates a metabolic master switch. The switch, an enzyme known as AMPK, acts like a gas gauge by sensing how much energy a cell has. When a cell has plenty of energy, AMPK remains inactive and the cell carries out its normal processes. If a cell runs on empty, LKB1 turns on AMPK, which puts a damper on cell growth and proliferation. When LKB1 is absent or disabled, cells facing starvation never get the message and simply continue to divide.

rapamycin immunosuppresant macrolide antibiotic, immunosuppression antibiotic

Right A Lkb1+/- mouse before and after treatment with rapamycin.  Image: Courtesy of Dr. David R. Vera, University of California, San Diego. Press release June 15, 2009,© Salk Institute for Biological Studies.

Polyketide antibiotics of bacterial origin can be grouped into two major categories, type I and type II, based on the compound structures and biosynthetic mechanisms. Type I polyketides are synthesized by large multifunctional enzymes, while type II polyketides are assembled by dissociated enzymes.

Polyketide natural products are known to possess a wealth of pharmacologically important activities, including antimicrobial, antifungal, antiparasitic, antitumor and agrochemical properties. These metabolites are ubiquitous in distribution and have been reported from organisms as diverse as bacteria, fungi, plants, insects, dinoflagellates, mollusks and sponges. The wide spectrum of activity of polyketides makes them economically, clinically and industrially the most sought after molecules.

Many polyketide products are well-known compounds such as Erythromycin A, a broad spectrum macrolide antibiotic, the antihelmintic agent, avermectin or the immunosuppressants: FK506 and rapamycin. Oleandomycin, rifamycin, lovastatin, oxytetracycline and reserveratrol are a few more of the thousands of polyketides discovered so far. Polyketides are usually categorized on the basis of their chemical structures.

Source:

  1. Hopwood, D.A. (1997). Genetic contributions to understanding polyketide synthases. Chem. Rev. 97, 2465-2497.

Polyene Macrolide Antibiotics Examples:

Avermectin

FK-506

Oligomycin B

Spiramycin

Amphotericin B

Flopristin

Oligomycin C

Streptogramin A

Azalide

Flucanazole

Oxytetracycline

Streptovaricin

Azithromycin

Flurithromycin

Pentamycin

Tilmicosin

Boromycin

Josamycin

Perimycin

Troleandomycin

Brefeldin A

Kinamycin

Pikromycin

Tulathromycin

Candicidin

Kitasamycin

Polyketide

Tylosin

Calicheamicin

Lovastatin

Pristinamycin IIA

Virginiamycin S1

Callystatin A

Macrocin

Pristinamycin IIA

 

Clarithromycin

Mepartricin

Rapamycin

 

Daunorubicin

Midecamycin

Resveratrol

 

Dirithromycin

Miocamycin

Rifamycin B

 

Echinocandin B

Monocerin

Roxithromycin

 

Filipin

Mycolactone

Roxithromycin

 

Epthilone B

Nargenicin

Solithromycin

 

Erythromycin A

Oleandomycin

Spiramycin

 

Fidaxomicin

Oligomycin A

Streptogramin A

 

 

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