THEORETICAL BASE FOR MULTIDIMENSIONAL CHARACTERISATION OF PLANT ESSENTIAL OILS - CASE OF CENTAUREA (ASTERACEA) ESSENTIAL OILS WITH GOOD ANTIMICROBIAL ACTIVITY

Due to an antibiotic resistance around 700, 000 people each year worldwide is life threatened and killed by drug-resistant microbes (1). Therefore the new antimicrobial agents are needed and search for them presents a top priority in this area of science (1). Recent interest in natural compounds has even risen due to a rapid development of resistant bacterial strains. This forced natural product re-evaluation as a source of novel chemical skeletons with antibacterial activity for elaboration in drug development (2). Centaurea genus, Asteraceae family, is widespread in worldwide area comprising around 400-700 species (3). They are well known, on medicinal purposes, in eastern Mediterranean ethno-pharmacology ; due to a variety of bioactive compounds they comprise (4). Good antimicrobial activity was previously reported for more than 20 Centaurea species essential oils, with more than 200 different compounds present. This presents a good model for development of mathematical tool in order to characterise the chemical compounds responsible for a good antimicrobial activity. Biological activity of essential oils is usually connected with the dominant components, but some compounds in minor percentage may also have a strong impact (3). Therefore, we have used mathematical tool to detect the specific combination of compounds responsible for antimicrobial activity. For the theoretical base for multidimensional characterisation we have developed variance-covariance matrix and calculated its eigenvalues and eigenvectors. This tool may be used for a focused research of compounds that have good antimicrobial activity, but also for detection of any other essential oil characteristics that can be utilized in cosmetics, pharmaceutical, food or any other industry.