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#macrolide(antibiotics)


             ANTIBIOTICS 

Macrolide:

Macrolide antibiotics are produced by various strains of streptomyces.they have 3 common chemical characteristics.
✓ a large non-planar strain less ring.
✓ a keto group.
✓ a glycosidically linked amino sugar.

  • Erythromycin
  • Clarithromycin
  • Azitromycin*                       

✓ Erythromycin, clarithromycin & Azitromycin comes under macrolides.
✓ All Macrolide Antibiotics have Lactone structures.
✓ Usually lactone ring has 12,14 or 16 atoms in it.

STRUCTURE OF LACTONE:







Erythromycin, clarithromycin & Azitromycin are similar in structure with small differences because of their 14&15 membered ring macrolides and also in placing of glucone moiety at 3 rd and 5 th positions .




ERYTHROMYCIN:



In erythromycin Hydrogen atoms in the OH group of 3rd and 5th positions is substituted with glucone moiety .

  • 3rd position-OCH3
      •  5th position-CH3.              

*Erythromycin was isolated from a culture of  strptomyces erythreus.
*it is a monoacidic base.
*Very bitter in taste .
*White / yellow crystalline powder.
*Erythromycin is insoluble in in alcohol but slightly soluble in water.
*It is most effective against Gram positive cocci,streptococci....etc.



CLARITHROMYCIN:(14 membered)




      •3rd position-OH
      •6th position-OCH3

*Chemically clarithromycin is 6-methyl-ether of Erythromycin.
*It is prepared by simply methylating Erythromycin at 6-hydroxyl group.
*It inhibits cytochrome P450 oxidase.
*Clarithromycin occurs as white crystalline solid.
*Practically insoluble in water,but sparingly soluble in alcohol &freely soluble in acetone 
*It is more expensive than erythromycin.


AZITROMYCIN:(15 membered)




  
         
*It is a semisynthetic derivative of Erythromycin.
*It is more stable than Macrolide antibiotics.
*Spectrum of antimicrobial activity is similar to Erythromycin & Clarithromycin.
*It is more active against Gram neagtive bacteria& less active against Gram positive bacteria .


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