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Due to the overuse of antibiotics in veterinary and human medicine, antibiotic-resistant strains are developing. Among them is Campylobacter jejuni, a major foodborne pathogen and the leading cause of bacterial gastroenteritis, i.e. campylobacteriosis. In addition to the search of novel antimicrobial agents, the identification of new targets for their action is becoming increasingly important. Plant extracts contain various compounds that could act as antibacterial agents. Sedum roseum has long been used in traditional medicine. Extracts from the underground organs of the plant contain a wide range of biologically active compounds with various pharmacological activities. Most of these extracts are obtained from wild plants, even though harvesting is prohibited in many countries. To preserve the natural sources of S. roseum and to ensure the quality and authenticity of the plant material, domestication and cultivation of the plant seems to be the best solution. In the present work, we used cultivated S. roseum plant material, i.e. “Mattmark” (the first synthetic S. roseum cultivar) and “Rosavine”. Ethanolic extracts of both plant materials were prepared and further fractionated to obtain fractions rich in different compounds or compound groups, i.e. salidroside, rosavins, proanthocyanidins, and/or flavonoids. In this work, for the first time, biologically active compounds or compound groups from S. roseum were separated into different fractions and the antimicrobial activity in relation to chemical composition of the extracts and their fractions was studied. We found that fractions rich in proanthocyanidins had the strongest antimicrobial effect against C. jejuni, with the lowest minimal inhibitory concentrations (MICs), the highest effect on quorum sensing (QS), reduction of motility and adhesion to the polystyrene surfaces. On the other hand, fractions without proanthocyanidins were less effective. We conclude that proanthocyanidins could be one of the crucial compound groups responsible for the antimicrobial activity of S. roseum ethanolic extracts. Since S. roseum is an expensive source of biologically active compounds, it would be beneficial to search for cheaper and more easily available material with similar proanthocyanidin pattern. In addition, further studies are needed to determine exactly how proanthocyanidins act as antibacterial agents against C. jejuni. Zaradi prekomerne uporabe antibiotikov v veterini in humani medicini, postajajo bakterije vedno bolj odporne nanje. Mednje sodijo tudi bakterije vrste Campylobacter jejuni, ki so najpogostejše s hrano prenosljive črevesne bakterije, ter predstavljajo glavni vzrok za bakterijski gastroenteritis pri človeku, tj. kampilobakteriozo. Poleg iskanja novih protimikrobnih učinkovin je potrebno iskati tudi nove tarče, na katere bi le-te delovale. Rastlinski izvlečki vsebujejo spojine s protimikrobnim delovanjem. Rožni koren se že vrsto let uporablja v tradicionalni medicini. Izvlečki iz podzemnih organov te rastline vsebujejo širok spekter biološko aktivnih spojin z različnim farmakološkim delovanjem. Večina izvlečkov izhaja iz rastlin, ki rastejo v naravi, čeprav je nabiranje v mnogih državah prepovedano. Zaradi želje po ohranjanju naravnih virov rožnega korena in z namenom zagotoviti kakovosten ter pristen material za pripravo izvlečkov, so rastlino začeli vzgajati izven njenega naravnega okolja. V nalogi smo uporabili vzgojeni rastlinski material rožnega korena, “Mattmark” (prvo sintetično sorto rožnega korena) ter “Rosavine”. Pripravili smo etanolne izvlečke iz obeh rastlinskih materialov, v nadaljevanju pa ločili različne spojine ali skupine spojin znotraj njih. Pridobili smo frakcije, ki vsebujejo veliko količino salidrozida, rosavinov, proantocianidinov in/ali flavonoidov. V nalogi smo prvič do sedaj biološko aktivne spojine ali skupine spojin, izolirane iz korenin rožnega korena, ločili na posamezne frakcije ter proučevali njihovo protimikrobno delovanje v odvisnosti od kemijske sestave. Ugotovili smo, da so frakcije obogatene s proantocianidini najbolj biološko aktivne, saj zavrejo rast bakterij vrste C. jejuni že v zelo nizkih koncentracijah, v največji meri zmanjšajo medcelično signaliziranje, gibljivost ter zmožnost pritrditve bakterij na polistirenske površine. Frakcije, ki niso vsebovale proantocianidinov, so bile manj protimikrobno učinkovite. Glede na rezultate sklepamo, da so proantocianidini ena od ključnih skupin spojin, ki je odgovorna za visoko protimikrobno učinkovitost izvlečkov, pridobljenih iz korenin rožnega korena. Ker pa rožni koren predstavlja drag vir biološko aktivnih učinkovin, bi bilo zanimivo poiskati cenejši in lažje dostopen material s podobnim spektrom proantocianidinov. Poleg tega bi bilo potrebno nadalje raziskati način, po katerem proantocianidini na bakterije vrste C. jejuni tako uspešno protimikrobno delujejo. |
