Chromatographic Isolation, Characterization and in vitro Cytotoxic Evaluation of Ageratum Conyzoides L.

Antimicrobial resistance remains a pressing global challenge, urging the search for safer and more effective natural alternatives. Ageratum conyzoides L., a traditionally used medicinal herb, was investigated for its antimicrobial activity and in vitro cytotoxic potential. Crude extracts prepared with methanol, chloroform, hexane, and water were screened against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and Aspergillus niger. Among them, the methanolic extract exhibited the strongest activity, with zones of inhibition ranging from ̴ (7-21) mm and MIC values of 1-4 mg/mL. Bioassay-guided fractionation yielded methanol, chloroform, and hexane fractions, with the methanolic fraction (MLLM) showing the highest potency (MIC 0.125 mg/mL). Structural elucidation using HPLC, TLC, LC-MS, FTIR, and ¹H-NMR identified a bioactive compound, characterized as (2E,4E,11E,13E)-14-(allyloxy)-7,8-dimethyltetradeca-2,4,11,13-tetraen-1-amine (C₁₉H₃₁NO), previously unreported in A. conyzoides. In addition to antibacterial effects, fractions showed moderate cytotoxicity against A549 lung cancer cells (IC₅₀: 89-141 µg/mL). These findings suggest that A. conyzoides contains unique phytocompounds exhibiting both antimicrobial and cytotoxic activities, making them promising candidates for developing new drugs against resistant pathogens.