Cytotoxic Effects of Probiotic Bacteria Lactobacillus acidophilus and Lactobacillus rhamnosus Grown in the Presence of Oleuropein on Human Prostate Cancer Cells

Authors : Hasan Ufuk CELEBİOGLU, Busenur ÇELEBİ, Yavuz ERDEN, Emre EVİN, Orhan ADALI

Pages : 55-59

View : 18 | Download : 12

Publication Date : 2020-03-27

Article Type : Research Paper

Abstract :Functional foods are groups of foods that have potentially positive effects on health beyond basic nutrition. Probiotics are beneficial microorganisms, being as a group of functional foods, and when ingested in adequate amounts, they possess positive health effects to host organisms. Lactobacillus acidophilus and Lactobacillus rhamnosus are two of the most studied and very well-known probiotic bacteria. They can have anti-carcinogenic functions, yet their exact mechanisms how they possess anti-carcinogenic activities are still under investigation. Another group of functional foods is plant-based phenolic compounds. They also have potential to possess anti-carcinogenic activities. Among them, oleuropein is very interesting and well-known phenolic compound naturally present in olive fruits and olive oil. As the phenolic compounds and probiotic bacteria can be present at the same time in human gastrointestinal tract, this study aims to investigate the in vitro cytotoxic effects of Lactobacillus acidophilus LA-5 (LA-5) and Lactobacillus rhamnosus GG (GG) grown in the presence of oleuropein on human prostate cancer cell line. To achieve this purpose, oleuropein was added to media of these bacteria and effects of cell-free supernatants of these combinations (phenolic+probiotic) on cytotoxicity of prostate cancer cell line PC-3 were investigated using MTT Method.  Concentrations of 0, 50, 100, and 250 µg/mL of oleuropein were added to bacterial cultures and no inhibition on growths of LA-5 or GG were observed. Cell surface hydrophobicity (i.e., adhesion to hydrophobic solvents) is an important feature for bacteria to be retained in gastrointestinal tract (GIT). MATS tests showed all concentrations of oleuropein decreased the surface hydrophobicity of GG, while a dose-dependent increase or decrease in surface hydrophobicity was observed in LA-5. Bacterial aggregation is defined as clustering of bacteria. Auto-aggregation studies showed oleuropein affected the aggregation of bacteria in a dose-dependent manner. Oleuropein added to the growth medium of LA-5 had additional effects on the cytotoxicity of cell-free supernatants of this bacterium. However, addition of oleuropein to the growth medium of GG did not show significant changes on the cytotoxicity of cell-free supernatants of this bacterium. Thus, the results indicate that new combinations of functional foods have potential to formulate new nutraceuticals. 
Keywords : Cytotoxicity, MTT Assay, phenolic compounds, probiotics, prostate cancer, oleuropein