(Z)-9,16-heptadecadien-7-one as main component of Chamaemelum mixtum essential oils: Original composition and biological activity against food-borne and nosocomial pathogens

International audience; The chemical compositions of the aerial parts essential oils of Chamaemelum mixtum (L.) Alloni from Corsica and Sardinia were investigated employing gas chromatography and gas chromatography/mass spectrometry. The structure of (Z)-heptadeca- 9,16-dien-7-one, a natural compound not previously described, was elucidated by gas chromatography/mass spectrometry (electron impact and chemical ionization) and one dimensional and two-dimensional nuclear magnetic resonance spectroscopy. The variation in Chamaemelum mixtum essential oil was studied and statistical analysis showed the clustering of oil samples into three groups according to the amount of oxygenated compounds; these groups correlated to the harvest area. The strong biological activity of the oxygenated fraction (minimum inhibitory concentration of less than 0.1 mg/mL) of the Corsican oil against Candida albicans, Citrobacter frendii, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes and Staphillococcus aureus can be attributed to the presence of irregular monoterpene alcohols and (Z)-heptadeca-9,16-dien-7-one.