Influence of bearberry extract (Arctostaphylos Uva Ursi L.) on gastrointestinal bacteria adhesion

Ekstrakt medvjetke se stoljećima koristi u tradicionalnoj i modernoj medicini za liječenje i ublažavanje tegoba izazvanih urinarnim infekcijama. Unatoč tome, točan mehanizam djelovanja biološki aktivnih tvari iz ekstrakta medvjetke do danas nije u potpunosti definiran. U ovom se radu proučavao i uspoređivao citotoksični učinak svježe pripremljenog i liofiliziranog vodenog ekstrakta medvjetke na bakterijama Escherichia coli, Staphylococcus aureus, Lactobacillus plantarum i Lactobacillus fermentum te utjecaj ekstrakta na njihovu adheziju za humane epitelne stanice gastrointestinalnog trakta u in vitro sustavu. Prethodno adheziji, napravljeni su testovi citotoksičnosti Neutral red metodom i testovi potencijalnog antioksidacijskog djelovanja ekstrakta DCHF-DA metodom na tumorskim epitelnim stanicama jezika (Cal27) i tumorskim epitelnim stanicama kolorektalnog adenokarcinoma (Caco-2). Dobiveni podaci ukazuju na jaki antimikrobni karakter ekstrakta na Gram-pozitivne bakterije te na sposobnost ekstrakta da dovede do promjene u adheziji bakterijskih stanica za epitelne stanice probavnog sustava. Ustanovljena je antioksidacijska aktivnost ekstrakta te stimulacija proliferacije humanih stanica koja ovisi o koncentraciji ekstrakta i vrsti tretiranih stanica. Usporedbom biološkog djelovanja svježe pripremljenog i liofiliziranog vodenog ekstrakta medvjetke nije uočena značajna razlika.The bearberry extract has been used for centuries in traditional and modern medicine to treat and alleviate the problems caused by urinary infections. Nevertheless, the exact mechanism of action of biologically active compounds from bearberry extract to date has not been fully defined. In this thesis the cytotoxicity effect of bearberry water extract,including the comparison between fresh and freeze dried extract effects on bacteria Escherichia coli, Staphylococcus aureus, Lactobacillus plantarum and Lactobacillus fermentum was studied. Furthermore, the influence of the extract on adhesion of aforementioned bacteria to human epithelial gastrointestinal tract cells in the in vitro system was studied. Before the adhesion tests, cytotoxicity tests using Neutral red method were carried out together with the tests of potential antioxidant activity of the extract using DCHF-DA method on tumor epithelial cells of tongue (Cal27) and of colorectal adenocarcinoma (Caco-2). The results obtained show a strong antimicrobial effect of this extract towards Gram-positive bacteria and also its ability to cause changes in the adhesion of bacterial cells to the epithelial cells of the digestive system. Antioxidant activity of the extract was established and stimulation of human cell proliferation was determined, which depends on the concentration of the extract and the type of treated cells. No significant difference was observed by comparing the biological activity of freshly prepared and freeze dried bearberry water extract