Comprehensive review on anti-microbial activity of Azadirachta indica (Neem) Bark extract and Gum extract

Abstract

The present study focuses on the preparation, characterization, and antimicrobial evaluation of Azadirachta indica (Neem) bark extract and its chemically modified derivative-acrylamide-grafted neem gum polysaccharide (NGP-g-Am). Neem bark, collected in mid-August, was processed to obtain a methanolic extract, which was subsequently characterized through physical and chemical evaluations, UV-visible spectrophotometry for λ max and purity determination, and structural elucidation using FTIR spectroscopy. The extract exhibited notable antimicrobial activity against selected bacterial and fungal strains, validating the traditional medicinal use of neem bark. In parallel, neem gum polysaccharide (NGP) was chemically modified via microwave-assisted free radical polymerization using acrylamide, guided by a three-level full factorial design. The resulting graft copolymer (NGP-g-Am) was extensively characterized using UV-visible spectroscopy, FTIR, scanning electron microscopy (SEM), contact angle measurements, biodegradability assessment, hemocompatibility testing, and pH-dependent swelling behaviour. Molecular docking studies revealed that both NGP and NGP-g-Am exhibit strong binding affinities to Toll-like receptor 4 (TLR-4), suggesting a possible mechanism for their observed antimicrobial activities. The enhanced biological performance of the grafted polymer compared to native neem gum highlights its potential application in biomedical fields, especially as a biocompatible antimicrobial agent. This review consolidates current findings on the dual approach of using both natural and modified neem-based materials for antimicrobial purposes, offering valuable insights into the development of sustainable and effective bioactive compounds.