Classification of Anti-malarial Drugs

 Antimalarial drugs can be classified based on their chemical structure and mode of action. Below is a classification with examples and corresponding structural features:

1. 4-Aminoquinolines

• Mechanism: Interfere with hemoglobin digestion in the parasite.
• Examples:
• Chloroquine
  Structure: Contains a quinoline ring attached to a secondary amine.

• Amodiaquine Structure: Similar to chloroquine, but has a hydroxyl group on the aromatic ring.

2. Aryl Amino Alcohols

• Mechanism: Inhibit heme detoxification within the parasite.
• Examples:
• Quinine
  Structure: A quinoline ring attached to an alcohol and an aromatic amine.

• Mefloquine
  Structure: Fluorinated aromatic ring with a piperidine ring attached to it.

3. 8-Aminoquinolines

• Mechanism: Active against liver stages of the parasite.
• Examples:
• Primaquine
  Structure: Quinoline ring attached to an amine group at the 8th position.

• Tafenoquine
  Structure: Modified primaquine with a fluorinated tail, improving its activity and half-life.

4. Antifolate Drugs

• Mechanism: Inhibit folate synthesis crucial for parasite DNA replication.
• Examples:
• Pyrimethamine
  Structure: Pyrimidine ring attached to two aromatic rings.

• Proguanil
  Structure: A biguanide group attached to a cyclohexane ring.

5. Artemisinin and Derivatives

• Mechanism: Generate free radicals within the parasite.
• Examples:
• Artemisinin
  Structure: A sesquiterpene lactone with a unique endoperoxide bridge.

• Artemether
  Structure: Methylated derivative of artemisinin.

6. Antibiotics (Used as Antimalarials)

• Mechanism: Inhibit protein synthesis within the parasite.
• Examples:
  • Doxycycline
    Structure: A tetracycline derivative with a four-ring structure.
  • Clindamycin
    Structure: A lincosamide antibiotic with a complex structure containing amino sugars.

7. Naphthoquinones

• Mechanism: Inhibit the mitochondrial electron transport chain.
• Example:
  • Atovaquone
    Structure: A naphthoquinone ring with hydrophobic substituents.