Introduction to types of Fungal Infections
Classification of Anti Fungal Agents
Chemistry of anti fungal agents
Azole Anti Fungal Agents
Mechanism of Action (MOA)
Structural Activity Relationship (SAR)
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Anti fungal agents
1. Anti Fungal Agents
Dr. Naga Prashant Koppuravuri, M.Pharm, Ph.D, FAGE.,
Assistant Professor,
Department of Pharmaceutical Chemistry
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• Mycology is the branch of biology concerned with the study of fungi
• A fungus is a eukaryote that digests food externally and absorbs nutrients
directly through its cell walls.
• Systemic Mycoses
• Cutaneous Infections (Dermatophytoses)
• Opportunistic Fungal Infections
12. Azole anti fungal agents
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• Azoles—Imidazoles and Triazoles
• Azole antifungal agents are the largest class of antimycotics available today,
with more than 20 drugs on the market
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Azoles inhibit the
oxidative
14-demethylation of
lanosterol blocking
ergosterol synthesis
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MECHANISM OF ACTION
• All the azoles act by inhibiting ergosterol biosynthesis through
inhibition of the 14a-demethylase, CYP51, discussed earlier under
ergosterol biosynthesis (Site 2).
• The N3 atom is essential for binding to the 14α-demethylase.
• The basic N3 atom of the azole forms a bond with the heme iron of
the CYP450 prosthetic group in the position normally occupied by the
activated oxygen.
• Increased levels of 14α-methyllanosterol, 4,14-dimethylzymosterol,
and 24-metheylene dihydrolanosterol result from this inhibition
weakening the fungal cell membrane leading to a leaky membrane.
20. Topical Agents for Dermatophytoses
• Since these infections tend to be topical, their treatment has been directed to
surface areas of the skin.
• The skin is a formidable barrier to drug penetration, and many of the topical
agents work best if an adjuvant is added that opens the barrier function of
the skin.
• Keratolytic agents such as salicylic acid or other -hydroxy compounds
perform this function reasonably well.
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Griseofulvin
(Grisactin, Gris-PEG, Grifulvin)
Penicillium griseofulvum
Other Antifungal Antibiotics
30. Allylamines and Related Compounds
• The allylamine class of antifungal agents was discovered as a result of
random screening of a chemical inventory for compounds with antifungal
activity.
• Structure–activity studies in the series subsequently led to the discovery of
compounds with enhanced potency and potential oral activity, such as
terbinafine.
• Investigation of the mechanism of action of the allylamines demonstrated
that the compounds interfere with an early step in ergosterol biosynthesis,
namely, the epoxidation of squalene catalyzed by squalene epoxidase.
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