Trakia Journal of Sciences, Vol. 7, No. 1, 2009 34 Trakia Journal of Sciences, Vol. 7, No. 1, pp 34-36, 2009 Copyright © 2009 Trakia University Available online at: http://www.uni-sz.bg ISSN 1313-7050 (print) ISSN 1313-3551 (online) Original Contribution STUDY ON ANTIBACTERIAL ACTIVITY OF HABERLEA RHODOPENSIS R. Radev 1* , G. Lazarova 2 , P. Nedialkov 3 , K. Sokolova 1 , D. Rukanova 1 , Zh. Tsokeva 1 1 Department of Pharmacology and Clinical Pharmacology, Trakia University, Stara Zagora 2 Department of Microbiology, Medical Faculty, Trakia University, Stara Zagora 3 Department of Pharmacognosy, Pharmaceutical Faculty, Medical University, Sofia, Bulgaria SUMMARY The present work is a preliminary study of the antibacterial activity of the total extract of the medicinal plant Haberlea rhodopensis. A total extract from Haberlea rhodopensis leaves macerated for 48 hours in 70% water-ethanolic solution with subsequent distillation of the ethanol in vacuum vaporizer to a drug/liquid phase proportion of 5:1, was used. The antibacterial activity of the extract was done on some standard and wild pathogenic bacterial strains. The testing was done by the disc- diffusion method using filter paper discs impregnated with the different concentration of the initial extract: undiluted or diluted 1:1 or 1:2. The results show that the inhibition of the bacterial growth was more pronounced on Staphylococcus aureus than on Gram –negative strains - Pseudomonas aeruginosa and Escherichia coli. A possibility of its antibacterial activity is discussed. Key words: medicinal herb, antimicrobial activity, Staphylococcus aureus, Escherichia coli. INTRODUCTION Various medicinal plants have been used for years in daily life to treat diseases all over the world1 Medicinal plants are an important therapeutic option for various diseases. According to World Health Organization, medicinal plants are a substantial source of a variety of newer herbal drugs. Haberlea rhodopensis belongs to the family Gesneriaceae and it is a Balkan endemic relict that is widely distributed mainly in the Rhodope Mountains and some regions of the Sredna gora Mountains and the Balkan Mountains. It represents a rîsette- like evergreen herb, which requires specific soil and climatic conditions for growing. Haberlea rhodopensis belongs to the so called ”resurrection plants” due to its ability to fall in anabiosis for a long time when there are unfavourable conditions and to restore back to normal when the conditions become appropriate. Haberlea rhodopensis is a relatively less explored plant. The basic studies are on the explanation of the mechanism of its * Correspondence to: Radoslav Radev; Department of Pharmacology and Clinical Pharmacology, Trakia University; Armeiska 11, 6000 Stara Zagora, Bulgaria; Tel.: +359888986966; E-mail: radoslav.radev@abv.bg anabiosis. It has been proven that in case of desiccation the herb is able to save a part of its water content while the metabolism continues at a very slow pace. There are assumptions that the remaining water forms a thin layer around proteins and thus protects them from denaturation.(1) The role of the lipids and the polysaccharides in the mechanism of anabiosis has been discussed.(2) Other studies are focused mainly on the antioxidant potential and thermo- and photostability of photosynthesis system (3,4,5) of the herb at different conditions. There are no sufficient data about the phytochemical composition in the accessible literature - a significant amount of chlorophyll and some enzymes (superoxiddimutasa, citratdehidrogenasa etc.) have been found. Flavonoids, flavonoid tannin, zeexantin, ascorbate, glutation (6) etc have been found in other species from the Gesneriaceae family. There is a lack of information about any antibacterial activity of the extract or separate phytochemical substances from the plant. According to the natives, Haberlea rhodopensis has been used for treatment of Paronichya contagiosa by adding it to the food of the animals. Additional investigations in specialized literature showed that this is probably a polyaetiologic disease whose current treatment includes different antibacterial