The essential oils and products of plant secondary metabolism had a wide application in folk medicine, fragrance industries, food flavouring and preservation but only in recent years they have started to be recognized for their potential antimicrobial role. Clinical experience has shown that the efficacy of antimicrobial agents depends not only on their direct effect on a given microorganism but also on the functional activity of the host immune system. The literature reports evidence suggesting that a larger number of plants and their constituents could show beneficial therapeutic effects, including anti-oxidant, anti-inflammatory and immunomodulatory activity, which still need to be further investigated. Since data on the effects of essential oils on innate immune system are scanty and fragmentary, the purpose of this study was to evaluate the intracellular killing activity of Thymus vulgaris L. essential oil (EO), against Candida albicans in human polymorphonuclear leukocytes (PMNs). In addition, in order to provide a frame of reference for the activity of this EO, its extracellular antifungal activity was also evaluated. For intracellular studies, human PMNs were infected with yeast cells and treated with the EO at 0.5x MIC. Killing values were expressed as the survival index (SI) after 30, 60 and 90 min of incubation. EO-free controls were also included. Extracellular studies in broth were performing using EO concentration from 0.1 to 2x MIC. Viable yeasts were enumerated at 0, 30, 60, 90, 120, 180 min and 24 h. Preliminary results showed that significant greater killing of C.albicans occurred intracellularly by PMNs, in comparison with EO-free controls. In extracellular killing assays we observed progressive growth of the yeast cells in the presence of drug dilutions below the 1xMIC. The mechanism of intracellular killing enhancement is still unknown, even if a possible synergistic antifungal interaction with human phagocytes could help to explain why this EO, which appeared to be only fungistatic in time-kill assays, had greater efficacy in killing yeast cells once simultaneously incubated with PMNs. These encouraging results require to be further confirmed, to better elucidate this issue.
Enhancement of human polymorphonuclear leukocytes activity by Thymus vulgaris L. essential oil against C.albicans
TULLIO, Viviana Cristina;SCALAS, Daniela;ROANA, Janira;MANDRAS, Narcisa;ALLIZOND, VALERIA;BANCHE, Giuliana;MERLINO, Chiara;CUFFINI, Annamaria
2010-01-01
Abstract
The essential oils and products of plant secondary metabolism had a wide application in folk medicine, fragrance industries, food flavouring and preservation but only in recent years they have started to be recognized for their potential antimicrobial role. Clinical experience has shown that the efficacy of antimicrobial agents depends not only on their direct effect on a given microorganism but also on the functional activity of the host immune system. The literature reports evidence suggesting that a larger number of plants and their constituents could show beneficial therapeutic effects, including anti-oxidant, anti-inflammatory and immunomodulatory activity, which still need to be further investigated. Since data on the effects of essential oils on innate immune system are scanty and fragmentary, the purpose of this study was to evaluate the intracellular killing activity of Thymus vulgaris L. essential oil (EO), against Candida albicans in human polymorphonuclear leukocytes (PMNs). In addition, in order to provide a frame of reference for the activity of this EO, its extracellular antifungal activity was also evaluated. For intracellular studies, human PMNs were infected with yeast cells and treated with the EO at 0.5x MIC. Killing values were expressed as the survival index (SI) after 30, 60 and 90 min of incubation. EO-free controls were also included. Extracellular studies in broth were performing using EO concentration from 0.1 to 2x MIC. Viable yeasts were enumerated at 0, 30, 60, 90, 120, 180 min and 24 h. Preliminary results showed that significant greater killing of C.albicans occurred intracellularly by PMNs, in comparison with EO-free controls. In extracellular killing assays we observed progressive growth of the yeast cells in the presence of drug dilutions below the 1xMIC. The mechanism of intracellular killing enhancement is still unknown, even if a possible synergistic antifungal interaction with human phagocytes could help to explain why this EO, which appeared to be only fungistatic in time-kill assays, had greater efficacy in killing yeast cells once simultaneously incubated with PMNs. These encouraging results require to be further confirmed, to better elucidate this issue.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
