FLUOROQUINOLONES
ASSOCIATED

PHOTOGENOTOXICITY

Dr. P.Naina Mohamed
Pharmacologist
FLUOROQUINOLONES
Structurally Quinolones contain a quinoline ring
system and hence given the name quinolones.
 Fluoroquin...
MECHANISM OF ACTION
Fluoroquinolones

Bind to the A-subunit of DNA gyrase (topoisomerase II
type) enzyme
Prevents the bind...
GRAM-POSITIVE AND GRAM-NEGATIVE
BACTERIAS


Gram-positive bacterias:




Fluoroquinolones inhibit DNA gyrase (topoisome...
DNA DAMAGE
Fluoroquinolones (High dose)
Direct binding of quinolones to DNA
Inhibition of topoisomerase IIα activity
Enhan...
PHOTOGENOTOXICITY
Fluoroquinolones +
Ultraviolet A (UVA) radiation
Formation of reactive oxygen species
DNA oxidation
Incr...
REFERENCES

http://toxsci.oxfordjournals.org/con

tent/69/1/16.full
http://www.ncbi.nlm.nih.gov/pubm
ed/14769204
http:/...
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Fluoroquinolones associated photogenotoxicity

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Higher concentration of Fluoroquinolones induce DNA damage by inhibiting human topoisomerase IIα activity.
Fluoroquinolones also cause DNA damage by DNA oxidation and inhibition human topoisomerase IIα, in presence of Ultraviolet rays.

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Fluoroquinolones associated photogenotoxicity

  1. 1. FLUOROQUINOLONES ASSOCIATED PHOTOGENOTOXICITY Dr. P.Naina Mohamed Pharmacologist
  2. 2. FLUOROQUINOLONES Structurally Quinolones contain a quinoline ring system and hence given the name quinolones.  Fluoroquinolones also contain a fluorine atom at the 6-position of the quinoline ring to increase the potency.  Fluoroquinolones and quinolones are not used for regular treatment of bacterial infections due to their severe side effects in rare cases.  They are generally used for more resistant strains of bacteria and are especially useful in genitourinary infections. 
  3. 3. MECHANISM OF ACTION Fluoroquinolones Bind to the A-subunit of DNA gyrase (topoisomerase II type) enzyme Prevents the binding of substrate to the active site of DNA gyrase Absence of formation of enzyme – substrate complex Blockade of unwinding of double-stranded DNA into a single stranded structure Prevention of synthesis of mRNA Inhibition of bacterial protein synthesis Antibacterial activity
  4. 4. GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIAS  Gram-positive bacterias:   Fluoroquinolones inhibit DNA gyrase (topoisomerase II), which is responsible for supercoiling of gram-positive bacterial DNA during DNA replication. Gram-negative bacterias:  But, in case of gram-negative bacteria, Fluoroquinolones inhibit topoisomerase IV, an enzyme responsible for relaxation of supercoiled circular DNA and separation of the inter-linked daughter chromosomes.
  5. 5. DNA DAMAGE Fluoroquinolones (High dose) Direct binding of quinolones to DNA Inhibition of topoisomerase IIα activity Enhanced pre- and post-strand DNA breaks DNA damage
  6. 6. PHOTOGENOTOXICITY Fluoroquinolones + Ultraviolet A (UVA) radiation Formation of reactive oxygen species DNA oxidation Increased binding of Fluoroquinolones to both the topoisomerase IIα and the DNA Inhibition of human topoisomerase IIα Prevention of topoisomerase IIα from recognizing and ligating DNA cleaved sites Enhanced pre- and post-strand DNA breaks DNA damage
  7. 7. REFERENCES http://toxsci.oxfordjournals.org/con tent/69/1/16.full http://www.ncbi.nlm.nih.gov/pubm ed/14769204 http://www.chinaphar.com/16714083/25/171.pdf

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