Role of thin layer chromatography in detection of antibacterial activity of essential oils

G Horváth; K Ács; W Jesionek; I Choma; A Böszörményi; B Kocsis

doi:10.1055/s-0035-1565831

Planta Medica, Table of Contents

Role of thin layer chromatography in detection of antibacterial activity of essential oils

G Horváth ¹, K Ács ¹, W Jesionek ², I Choma ², A Böszörményi ³, B Kocsis ⁴

¹University of Pécs, Medical School, Department of Pharmacognosy, Rókus u. 2., 7624, Pécs, Hungary
²Maria Curie-Sklodowska University, Faculty of Chemistry, Department of Chromatographic Methods, M. Curie-Sklodowska Sq. 3, 20 – 031, Lublin, Poland
³Semmelweis University, Faculty of Pharmacy, Institute of Pharmacognosy, Ülloi út 26, 1085, Budapest, Hungary
⁴University of Pécs, Medical School, Institute of Medical Microbiology and Immunology, Szigeti út 12., 7624, Pécs, Hungary

Abstract

The appearance of multidrug resistant bacteria and growing antibiotic resistance increased the significance of natural drugs against infections. Results of the previous in vitro studies focusing on the antimicrobial activity of essential oils (EOs) are very different, sometimes their reliability is questionable. Thin layer chromatography-direct bioautography (TLC-DB) belonging to the effect-directed analysis (EDA) provides information for the biologically active compounds even in a multiple matrices [1]. The aim of our study was the chemical characterization of different EOs (citronella, chamomile, clove, cinnamon bark, thyme and tea tree) using GC-MS and the investigation of their antibacterial activity by TLC-DB. EOs were isolated by water-steam distillation or obtained from a Hungarian drug store chain. Furthermore, semi-quantitative densitometric evaluation of EOs and their main components was done by CAMAG VideoScan program (Muttenz, Switzerland). Citronellal (36.2%), α-bisabolol (62.9%), eugenol (88.6%), trans-cinnamic aldehyde (74.0%), thymol (46.3%) and terpinene-4-ol (44.0%) was the main component of the EO of citronella, chamomile, clove, cinnamon bark, thyme and tea tree, respectively. Clove, cinnamon bark and thyme EOs were the most active oils against Staphylococcus aureus, S. epidermidis, MRSA and Escherichia coli in 30 mg/mL concentration (equivalent to 0.15 mg of pure oil). After TLC separation the antibacterial activity of citronellal, α-bisabolol, eugenol and thymol could be demonstrated. Citronellal (0.01 mg) showed the highest activity. TLC-DB bioassay allows a rapid identification of the antibacterial compound in a complex mixture, e.g. in EOs.

Acknowledgements: This work was supported by OTKA PD 104660 grant (Hungarian Scientific Research Fund).

References:

[1] Choma IM, Grzelak EM. Bioautography detection in thin-layer chromatography. J Chromatogr A 2011; 1218: 2684 – 2691