Page 125 - Pharmd general phytochemistry I-Final2024_LEUCTERS

Aminoglycoside Antibiotics

 Since the isolation of streptomycin in 1944, a great number of new Aminoglycoside
Antibiotics have been discovered.

Occurrence:
 Aminoglycosides are isolated from the actinomycetes and particularly from the

genus Streptomyces, e.g.: streptomycin, kanamycin, neomycin, paromomycin,
gentamycin, and tobramycin. Amikacin is a semi-synthetic derivative of
kanamycin.
Chemical composition:
 The aminoglycoside antibiotics are characterized by the presences of 1,3-
diaminoinositol derivative: streptidine, 2-deoxystreptamine or spectinamine.

Streptidine 2-Deoxystreptamine Spectinamine

 Some of the alcoholic functions of these compounds are substituted through

glycosidic bonds with characteristic amino sugars to form pseudo-

oligosaccharides.

Chemistry, spectrum, potency, toxicity and pharmacokinetics:
 Aminoglycosides are basic, freely water soluble.
 They form acid salts where they are generally available. They are not absorbed

from the gastrointestinal tract.
 They are excreted in active form in fairly large amounts in the urine.
 When given orally, their action is primarily confined to the gastrointestinal tract.
 They are more commonly given intramuscularly or by perfusion.
 Because of their potent broad-spectrum nature of their antimicrobial activity, they

are also used for the treatment of systemic infections.
 They act directly on the bacterial ribosome, where they inhibit protein synthesis and

interfere with the fidelity of translation of the genetic message.

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