Transcript Macrocyclic lactone antibiotics

Macrocyclic lactone antibiotics
• This family includes 4 subfamilies which are:
1- Macrolide
2- Polyene
3- Other macrocylic lactone
• A group of antibiotics containing a macrocyclic
lactone ring linked glycosidically to one or
more sugar moieties. These antibiotics are
produced by certain species of Streptomyces.
They often inhibit protein synthesis by binding
to the 50S subunits...
Erythromycin
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It has 14 membered lactones.
It is whitish, fairly yellow crystalline substance
Soluble in water
It is unstable at room temperature.
It is only stable in neutral solutions for weeks
at refrigerators temperature.
Absorption
• Erythromycin base is absorbed in the small
intestine, but its activity is reduced due to the
action of acid in the stomach.
• It is excreted in bile
• It crosses the placental barrier
Antibacterial action
• It inhibits protein synthesis of E.coli.
• For the relatively narrow spectrum of
erythromycin it causes less changes in the
intestinal flora than expected with broad
spectrum antibiotics.
Toxicity:Fever, Skin eruption, gastrointestinal
upset, Diarrhoea are among the common
toxicity.
Polyene antibiotics
• Amphotericin B is a polygene antifungal
drug, often used intravenously because it is
poorly absorbed from the intestinal tract.
• It was originally extracted from Streptomyces
nodosus, a filamentous bacterium.
• Its name originates from the chemical's
amphoteric properties.
• Two amphotericins, Amphotericin A and
Amphotericin B are known, but only B is used
clinically because it is significantly more active
in vivo
• It is used to treat fungal meningities
• In this case amphotricin is given intrathecally
through the cerebrospinal fluid.
Side effects
• Amphotericin B is well-known for its severe and
potentially lethal side effects.
• Very often a serious acute reaction after the infusion (1
to 3 hours later) is noted consisting of high fever,
hypotension, anorexia, nausea, vomiting, headache,
drowsiness, generalised weakness.
• This reaction sometimes subsides with later
applications of the drug and may in part be due to
histamine liberation.
Nystatin
Antimicrobial Action
• It increases the leakage of intracellular
components from sterol-containing mycellium
especially sugar and protein components but
do not cause lysis of the organism.
Other macrocyclic lactone
• E.g: Boromycin
Belong to ionophorous antibiotics
Brefeldin A
• Antifungal
• Has cytotoxic properties