Chemical composition and antimicrobial investigation of the essential oil isolated from <i>Montanoa bipinnatifida</i> (Kunth) K. Koch leaves

<i>Montanoa bipinnatifida</i> is a perennial shrub belonging to family Asteraceae and geographically distributed in Mexico, Central America and Northern South America. This study aimed to investigate the chemical composition of the essential oil isolated from <i>M. bipinnatifida</i> leaves through GC-MS analysis accompanied by in-depth investigation of antimicrobial properties against wide arrays of microbial strains via agar diffusion method and disk diffusion method. The GC-MS analysis of the tested oil revealed presence of sixteen components (∼99.99%), predominated by germacrene D (37.22%), β-caryophyllene (30.73%), α-pinene (4.56%) and β-germacrene (4.48%). The undiluted oil exhibits varying levels of activity against different microbes. The leaf oil showed a significant inhibition against <i>Proteus mirabilis</i>, <i>Staphylococcus aureus</i>, <i>Bacillus subtilis</i> (both vegetative and spores), <i>Mycobacterium phlei</i>, and <i>Candida albicans</i>. However, its activity against <i>Sarcina lutea</i>, <i>Escherichia coli</i>, <i>Klebsiella pneumoniae</i> appears to be less pronounced. Thus, the leaf oil of <i>M. bipinnatifida</i> demonstrates broadspectrum antimicrobial activity and is recommended in the pharmaceutical industry to overcome the current problem related to the microbial resistance to antibiotics. Further experimental studies are warranted to investigate the underlying mechanism of action and the responsible individual components.