Phytochemical evaluation of Amomum dealbatum Roxb. rhizome and correlating bactericidal activity with GC profiling of its essential oil

Plant-derived essential oils are prioritised as alternative antimicrobial agents to synthetic medications. To address this need, the present study investigated the phyto-pharmacognostic properties and safety of the rhizome of Amomum dealbatum Roxb. that includes the isolation, characterization, and antibacterial evaluation of its essential oil. The work followed Pharmacopeial guidelines for phyto-pharmacognostic characterization using macro and microscopy and HPTLC whereas residual analyses like aflatoxins, heavy metals and pesticides were conducted using HPLC, AAS and GC-MS respectively. The essential oil from rhizome was extracted through hydro-distillation and tested against different bacterial strains through MIC. Essential oil was analyzed by conventional GC and two-dimensional GC using mass spectrometry as detector. The findings established a framework for identifying the rhizome, and the residual analyses confirmed its purity and safety as per regulatory guidelines. Two-dimensional GC identified 51 phytoconstituents whereas, 19 compounds were identified by conventional GC belong to major classes like, monoterpene and sesquiterpenoids. Essential oil predominantly contains monoterpenes like geraniol (7.23%), pinocarvone (5.65%), linalool (7.23%) and alcohol like santanilol (14.25%). Notably, the essential oil exhibited significant bactericidal activity against both Gram-positive and Gram-negative bacterial strains, the range being 1/16th to 1/64th dilution of the crude oil extract, as evident from the micro-broth dilution assay. The most promising effect was against Staphylococcus aureus as the Minimum bacterial concentration (MBC) was the lowest among all strains ( Salmonella sp., E. coli , Enterococcus faecalis ). Overall, the study validated the identity of the A. dealbatum rhizome with first detailed Pharmacognostic and 2D GC profiling of A. dealbatum rhizome and essential oil highlighting its potential antimicrobial property.