Title: Supercritical fluid chromatographic technique as an alternative to separate isomers of urolithin conjugates
Abstract:
Microbiota metabolites, which seem to be responsible of health beneficial effects, are produced in humans after the intake of foods. Urolithins are a class of them that can be found in foods that contain ellagitannins and ellagic acid. After their absorption, they are conjugated with glucuronic acid producing then different regiosimeric isomers, and being mainly present as urolithins glucuronides circulating in plasma and reaching the different tissues. Different metabotypes have been reported depending on the final produced urolithins: Urolithin A, isoUrolithin A and Urolithin B whose glucuronides could be produced in diverse quantities with difference in regional isomers in individuals due to enzyme polymorphins. However, the developed methodologies to date have some limitations due to not provide enough resolution to identify and quantify the different isomers in biological samples. Reverse phase high performance liquid chromatography analysis is the chosen technique in which Uro-A 3- and 8-glucuronide and isoUro-A- 9-glucuronide eluted together and only isoUro- A 3-glucuronide and Uro-B glucuronide are usually sufficiently resolved. For that reason, supercritical fluid chromatography using chiral columns is presented as an alternative technique to achieve the separation of the five urolithin glucuronides for the first time. The proposed method was applied to analyze these metabolites in urine samples from different volunteers belonging to different metabotypes using a Whelk-O® 1 column in less than 15 minutes. In general, volunteers in who both isomers of Urolithin A glucuronides were detected are in similar proportions, while isoUro A-3-glucuronide is the most common isomer against isoUro A-9-glucuronide. This work could represent a significant advance to improve metabotype assignment and their implications in human health.
Audience Take Away Notes:
- Supercritical fluid chromatography could be considered as a greener alternative to traditional chromatographic techniques to separate isomers of metabotypes with biological functions.
- The separation of the five urolithin glucuronides was achieved for the first time, which represent a significant advance in chromatography using lesser known columns than those used in reverse phase.
- Moreover, this work could be an important step to improve the urolithin metabotype assignment and their implications in inter-individuals variations in ellagitannin metabolism and their effect in human health.
