Aminoglycosides

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Historical Background of Aminoglycosides

• Aminoglycosides First discovered in 1944 (Streptomycin by Selman Waksman).

• Used mainly for Gram-negative infections and tuberculosis.

Nomenclature

• Contain amino sugars linked by glycosidic bonds.

• Common names:

  • Streptomycin

  • Neomycin

  • Kanamycin

Stereochemistry

• Multiple chiral centers in aminosugar moieties.

• The specific orientation of hydroxyl and amino groups affects activity and bacterial binding.

Structure-Activity Relationship (SAR)

• 1,3-diaminoinositol core: Essential for ribosomal binding.

• Aminosugar modifications:

  • Improve ribosome binding.

  • Influence resistance to modifying enzymes.

• Hydroxyl and amine groups interact with rRNA, causing misreading of mRNA.

Chemical Degradation Classification

• Oxidative degradation: Leads to inactive products.

• Enzymatic modification: By bacterial enzymes (acetylation, phosphorylation).

• Hydrolysis in acidic conditions.

Important Products

• Streptomycin (first discovered, used for TB).

• Gentamicin (broad-spectrum use).

• Amikacin (resistant to aminoglycoside-modifying enzymes).

• Neomycin (topical use).

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