Antimicrobial properties of the linalool-rich essential oil of Hyssopus officinalis L. var decumbens (Lamiaceae)

The antimicrobial activity of essential oil of Hyssopus officinalis L. var decumbens and Hyssopus officinalis L. was studied taking account of their chemical composition determined by GC and GC-MS. Pinocamphone and isopinocamphone were present in H. officinalis according to the ISO 9841 Standard (1991 E) but they were lacking in var. decumbens, where linalol (51.7%), 1,8-cineole (12.3%) and limonene (5.1%) instead are predominant. The disc diffusion tests carried out on Staphylococcus aureus and Enterococcus spp. and onKlebsiella oxytoca, Escherichia coli, Proteus mirabilis, Pseudomonas spp, and two strains of Salmonella spp., showed an antimicrobial activity generally negligible for H. officinalis, but broader, and in a few cases more evident for var. decumbens. All yeasts tested (seven strains of Candida) were strongly inhibited by both species. The effect of var. decumbens was generally bactericidal.