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Synthesis of Thymol Derivatives as Potential Non-Irritant Antimicrobial and Insecticidal Agents

[ Vol. 15 , Issue. 1 ]


Mostafa M.M. El-Miligy*, Aly A. Hazzaa, Saad R. El-Zemity and Ahmed K. Al-Kubeisi   Pages 125 - 137 ( 13 )


Background: Thymol has been reported to have a variety of antimicrobial and insecticidal activities but it has irritation side effect due to its phenolic nature.

Methods: A new series of potential non-irritant non-phenolic thymol derivatives were designed to hybridize the well-known biologically active thymol scaffold with various five membered heterocyclic antimicrobial and insecticidal pharmacophores like 1,3,4-oxadiazole, 1,3,4-thiadiazole, 1,2,4-triazole, thiazole and 4-thiazolidinone through different spacers. The target compounds were biologically evaluated for their in vitro antibacterial, antifungal and insecticidal activities.

Results: Compounds 4b and 9c showed weak antibacterial activity against S. aureus and B.subtilis with the inhibition zone diameters ranging from 2 to 7 mm and 4 mm respectively compared with ciprofloxacin with the inhibition zone diameter of 21 mm. Compounds 9a, 7d and 13b showed weak antibacterial compounds against B. subtilis with inhibition zone diameters 4, 4 and 6 mm respectively. Compounds 12b, 9c and 7a showed 20% insecticidal activity at a concentration of 0.157 mg/cm2 for each compound against Tribolium castaneum (Herbst) and Sitophilus oryzae (L.). Compound 6 showed moderate larvicidal activity against Culex pipiens with 40% mortality at a concentration of 1000 ppm.

Conclusion: Compound 9c showed weak dual antimicrobial and insecticidal activities.


Thymol, insecticide, antimicrobial, azoles, azolidinones, morphology.


Pharmaceutical Chemistry Department, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Pharmaceutical Chemistry Department, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Department of Chemistry and Technology of Pesticides, Faculty of Agriculture, Alexandria University, Alexandria 21521, Faculty of Pharmacy, Baghdad University, Baghdad

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