Chemical profiling by HPLC‐DAD and GC‐MS analysis and antimicrobial potential of Achillea santolina plant extracts against ESBL‐ producing E. coli and fungal pathogens

The study examines the chemical composition and antimicrobial properties of petroleum ether and hydro‐methanolic extracts of Achillea santolina(A. santolina) from Algeria. Chemical profiling was performed using High‐Performance Liquid Chromatography with Diode Array Detection (HPLC‐DAD) for the hydro‐methanolic extract and Gas Chromatography‐Mass Spectrometry (GC‐MS) for the petroleum ether extract. Antibacterial and antifungal activities were evaluated using the disc diffusion method and broth dilution technique. Epicatechin (24.54 mg/g extract), and camphor (19.18 %) were identified as main compounds in the hydro‐methanolic and petroleum ether extracts, respectively. Both extracts showed significant antibacterial effects against extended‐spectrum beta‐lactamase (ESBL)‐producing Escherichia coli (E. coli ) strains, with inhibition diameters ranging from 10 to 13 mm, and Minimum Inhibitory Concentration (MIC) values between 0.78 and 3.5 mg/mL. Anti‐fungal activity was also notable, particularly against Candida albicans (C. albicans ), with an inhibition diameter of 14 mm, and MIC values between 0.39 and 1.56 mg/mL. The hydro‐methanolic extract showed up to 90% of growth inhibition against Aspergillus niger (A. niger). These findings suggest that Achillea santolina could serve as a promising source of antimicrobial compounds to combat resistant pathogens.