Antimicrobial activity and chemical composition of essential oil from Helichrysum microphyllum Cambess. subsp. tyrrhenicum Bacch., Brullo & Giusso collected in South-West Sardinia

The aim of this study was to evaluate the chemical composition and the antimicrobial activity of essential oils of Helichrysum microphyllum subsp. tyrrhenicum collected in four different stations in South-Western Sardinia. The composition of the essential oils was determined by gas chromatography and gas chromatography/mass spectrometry. The oil samples showed different chromatographic profiles. The oil of the station 4 revealed the presence of significant amount of neryl acetate (33.6%); in oils from stations 1 and 2 we found γ-curcumene (28%) and in station 3 γ-curcumene (12%) and linalool (11%), while there was no trace of neryl acetate. Standard microbiological assays demonstrated that essential oils obtained by plants collected in station 1 and 2, very rich in curcumene, showed an interesting anticandidal activity, dose- and time-dependent, which is enhanced by sub-inhibitory concentrations of chitosan. Our results suggest that the essential oil of Helichrysum microphyllum subsp. tyrrhenicum, associated with chitosan in innovative formulations, could be considered as a therapeutic alternative in the treatment of Candida opportunistic infections. The results of this study shows that the chemotypization of the species examined could lead to their targeted clinical use, in a concept of a rational scientific aromatherapy.