Abstract

ANTIMICROBIAL EVALUATION OF SOME NEW 3-SUBSTITUTED-4(3H)-QUINAZOLINE

Ms. Supriya Ojha*, Dr. Arun Kumar Patel, Mr. Shivam Kurmi, Mr. Shailendra Patel

Abstract

Quinazoline derivatives represent an important class of heterocyclic compounds with diverse pharmacological activities, including antimicrobial, anticancer, anti-inflammatory, and antiviral effects. The present study focuses on the synthesis and antimicrobial evaluation of novel 3-substituted-4(3H)-quinazoline derivatives. The compounds were synthesised via multistep reactions starting from substituted anthranilic acid derivatives, followed by cyclisation and substitution. The synthesised compounds were characterised using spectral techniques such as IR, NMR, and mass spectrometry. The antimicrobial activity of these derivatives was evaluated against selected Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungal strains (Candida albicans and Aspergillus niger) using the agar diffusion method. Several derivatives exhibited moderate to significant antimicrobial activity compared to standard drugs. Structure –activity relationship analysis suggested that electron-withdrawing substituents at the 3-position enhance antimicrobial activity. The increasing prevalence of antimicrobial resistance has necessitated the discovery and development of novel therapeutic agents. Quinazoline derivatives have emerged as promising scaffolds in medicinal chemistry due to their diverse biological activities. This research focuses on the synthesis, characterisation, and antimicrobial evaluation of a series of newly developed 3 -substituted-4(3H)-quinazolines. The compounds were assessed against a panel of Gram-positive, Gram-negative bacteria, and fungal strains using standard in vitro methods. The structure-activity relationship (SAR) was explored to identify key functional groups responsible for enhanced activity. The findings indicate that certain substitutions at the 3-position significantly improve antimicrobial efficacy, providing a foundation for further preclinical investigation. These indicates that 3-substituted-4(3H)-quinazoline derivatives may serve as promising scaffolds for the development of new antimicrobial agents.

Keywords: Quinazoline, antimicrobial activity, synthesis, structure-activity relationship, drug design.