Effect of saponin-rich extracts from Quillaja saponaria solely and in combination with Yucca schidigera on adhesion of lactobacilli

Bc. Eva Vacíková

Master's thesis

Abstract:

Quilaja saponaria, a tree native to Chile, and Yucca schidigera, a plant native to the deserts of North America, are important for their content of secondary metabolites with an excellent biological activity and proven safety. Saponins from these two species are used as ingredients in food, beverages, cosmetics as a medicine and as additive for livestock feed. It has been demonstrated that these saponins are beneficial in lowering ammonia emissions, litter moisture, and footpad dermatitis in chickens. They can also improve food digestibility and thus promote growth, provide antioxidant activities, reduce coccidiosis-related damages, etc. Due to these properties, these saponins have great potential in replacing antibiotics used commercially in animal fattening. The aim of this thesis was to determine the cytotoxicity of the pure Q. saponaria extract (QS) and extract of the combination of Q. saponaria and Y. schidigera (QY) and then to test the adhesion of probiotic lactobacilli in the presence of these extracts to human carcinoma colonic epithelial cell line. The plant extracts were digested using the static in vitro static digestion model INFOGEST and subsequently used in cytotoxic and adhesion experiments on the cell culture model. For the determination of cytotoxicity, the MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-Diphenyltetrazolium Bromide) cytotoxicity assay was used to measure the cell viability; 3 common human lactobacilli (Lactobacillus brevis, L. gasseri and Lacticaseibacillus rhamnosus) and co-culture of epithelial cell lines (Caco-2 and HT29) was then used in the adhesion experiment. The cytotoxicity of the extracts was determined separately on two cell lines HT29 and Caco-2. The cytotoxicity of QS extract was IC20 = 172 and IC50 = 419 μg/ml for the Caco-2 cell line, while no cytotoxic effect was observed for the HT29 cell line. In the case of QY extract IC50 = 304 μg/ml for the Caco-2 cell line. No IC20 was determined for Caco-2 cell line as well as no cytotoxic effect was observed for the HT29 cell line in tested concentrations of QY extract. Adhesion results showed that QS and QY extracts significantly reduced the adhesion of all bacteria species tested. The only exception was L. rhamnosus, for which the QY extract caused an increase in adhesion at the lowest concentration. In general, QY extract reduced adhesion much less than QS extract. Only in L. rhamnosus was the decrease in adhesion clearly dependent on the concentration of both extracts used.

Keywords

adhesion, Soapbark, saponins

Language used: English

Date on which the thesis was submitted / produced: 28. 4. 2024

Thesis defence

• Date of defence: 4. 6. 2024
• Supervisor: Ing. Olga Leuner, Ph.D.
• Reader: Matěj Božik, Ph.D.

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme:
Tropical Crop Management and Ecology