Cymbopogon martinii (Roxb.) Wats var. motia essential oil (EO) is usually isolated by steam distillation of the freshly harvested
leaves or partially dried leaves [1]. Palmarosa has been widely used in aromatherapy
as a tonic skin due its antibacterial, antiviral and anti-inflammatory activity. It
has also been used in Ayurvedic medicine for skin problems and to relieve pain [1]. Propionibacterium acnes is the microorganism associated with the pathogenesis of acne; it is a gram-positive
bacteria and anaerobic opportunistic [2] and is an important factor in the activation
of innate immunity in acne [3]. The aim of this research was to evaluate if C. martinii EO and its major compound, geraniol (constitute ≈ 85% of the EO), are able to modify
the immune stimulation caused by P. acnes. We determined the antibacterial activity of C. martinii EO and geraniol for P. acnes in vitro. Sensitivity test broth micro dilution was performed and phenotypic changes were
confirmed by Transmission Electron Microscopy (TEM) and we investigated if the presence of C. martinii EO and geraniol modify the effect of P. acnes in the differentiation of T-cells. We determined the Minimum Inhibitory Concentration
(MIC) to P. acnes ATCC 11828 (type II) and ATCC 6919 (type IA) [See Table 1]. Peripheral blood mononuclear
cells from six volunteers were infected with P. acnes strains with a multiplicity of infection = 3 and simultaneously treated with 3 different
doses of C. martinii EO and geraniol, respectively. The treatments did not modulate the production of Interferon-gamma
and Interleukin-17 in CD4 + cells in PBMC's infected with P. acnes. Given these preliminary results, natural compounds tested showed antimicrobial activity
against P. acnes strains and they do not modulate P. acnes- stimulated lymphocytes T helper 1 and Th17 immune response. P. acnes showed differences in sensibility test depending of subtype and probably geraniol
is the responsible compound for the antimicrobial activity of the EO of C. martinii.
Tab. 1: Minimum inhibitory concentration of C. martinii EO and geraniol in micro dilution test to P. acnes
|
P. acnes Strains
|
MIC of C. martinii EO (µg/mL)
|
MIC of Geraniol (µg/mL)
|
|
ATCC 11828
|
700
|
800
|
|
ATCC 6919
|
1500
|
1500
|
Acknowledgements: grant 2015/12906 – 0, São Paulo Research Foundation (FAPESP).
Keywords:
Cymbopogon martinii, geraniol, essential oil, P. acnes, lymphocyte.
References:
[1] Rajeswara Rao B R. Biomass and essential oil yields of rainfed palmarosa (Cymbopogon martiniii (Roxb.) Wats. var. motia Burk.) supplied with different levels of organic manure
and fertilizer nitrogen in semi-arid tropical climate. Ind Crops Prod 2001; 14: 171
– 178
[2] Kistowska M. et al. Propionibacterium acnes Promotes Th17 and Th17/Th1 Responses in Acne Patients. J
Invest Dermatol 2014; 135: 110 – 118
[3] Christensen G J and Brüggemann H. Bacterial skin commensals and their role as host guardians. Benef Microbes 2014;
5: 201 – 215