Influence of antibiotics on the ellagic acid biotransformation in ex vivo incubations with gut microbiota

The activity of orally taken ellagitannins is mostly dependent on the ability of individual gut microbiota to produce urolithins [ 1 ]. Thus, regardless of the urolithin metabotype, the antibiotics might influence species responsible for the ellagic acid biotransformation [ 2 ]. The study aimed to investigate how various antibiotics influence the urolithins’ production in anaerobic co-incubations with gut microbiota and ellagic acid, used as the substrate. The experiments were conducted using fecal samples from different donors. The samples were taken at several time points and analyzed using LC-HRMS. The biotransformation was most often halted at the step of the conversion of ellagic acid to urolithin M5, and urolithin M6 to urolithins M7 and C ([ Fig. 1 ]). The antibiotics that caused the inhibition of urolithin production in most of the experiments were amoxicillin and ciprofloxacin. The results showed high interindividual variability, and no particular pattern was observed for specific metabotypes. Fig. 1 Ellagic acid biotransformation pathway – model control and incubations with antibiotics. Example of results for a single urolithin metabotype B donor. Urolithin E was not observed. Funding The presented research was financially supported by the European Union Horizon Europe MSCA-PF grant No. 101106272. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany