The increasing recognition and importance of fungal infections, the difficulties encountered in their treatment and the increase in resistance to antifungal agents have stimulated the search for new therapeutic alternatives. 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, in this study the interaction of Thymus vulgaris L. essential oil (EO), known for its antibacterial and antifungal activity, with human polymorphonuclear leukocytes (PMNs) was evaluated, focusing on intracellular killing towards a clinical Candida albicans strain. Intracellular killing was investigated by incubating the yeast cells (10*6 blastoconidia/ml) and PMNs (10*6 cells/ml) at 37 °C for 30, 60 and 90 min with ½ x MIC of EO. EO-free controls were also included. Killing values were expressed as the survival index (SI), which was calculated by adding the number of surviving yeast cells at T0 to the number of survivors at Tx, and dividing by the number of survivors at T0. According to this formula, if fungal killing was 100% effective, the SI would be 1. Preliminary results showed that ½ x MIC of EO significantly increased the intracellular killing by PMNs, in comparison with EO-free controls. The mechanism of such enhancement is still unknown, although EO direct damage to the yeast cell may, at least in part, be responsible, resulting in changes that make the yeast cells more susceptible to PMN lytic mechanisms. These encouraging results require to be further confirmed, to better elucidate this issue
Thymus vulgaris L. essential oil enhances the intracellular killing of Candida albicans by human polymorphonuclear leukocytes
TULLIO, Viviana Cristina;BANCHE, Giuliana;ALLIZOND, VALERIA;SCALAS, Daniela;MANDRAS, Narcisa;ROANA, Janira;CARLONE, Nicola;CUFFINI, Annamaria
2010-01-01
Abstract
The increasing recognition and importance of fungal infections, the difficulties encountered in their treatment and the increase in resistance to antifungal agents have stimulated the search for new therapeutic alternatives. 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, in this study the interaction of Thymus vulgaris L. essential oil (EO), known for its antibacterial and antifungal activity, with human polymorphonuclear leukocytes (PMNs) was evaluated, focusing on intracellular killing towards a clinical Candida albicans strain. Intracellular killing was investigated by incubating the yeast cells (10*6 blastoconidia/ml) and PMNs (10*6 cells/ml) at 37 °C for 30, 60 and 90 min with ½ x MIC of EO. EO-free controls were also included. Killing values were expressed as the survival index (SI), which was calculated by adding the number of surviving yeast cells at T0 to the number of survivors at Tx, and dividing by the number of survivors at T0. According to this formula, if fungal killing was 100% effective, the SI would be 1. Preliminary results showed that ½ x MIC of EO significantly increased the intracellular killing by PMNs, in comparison with EO-free controls. The mechanism of such enhancement is still unknown, although EO direct damage to the yeast cell may, at least in part, be responsible, resulting in changes that make the yeast cells more susceptible to PMN lytic mechanisms. These encouraging results require to be further confirmed, to better elucidate this issue
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