Comparative analysis of biotransformation of trans‐resveratrol in worms, flies, mice and humans
Authors: Kulling Sabine E. , Soukup Sebastian T , Rieck Florian , Spanier Britta , Schulze Christine , Piegholdt Stefanie , Rechkemmer Gerhard , Wagner Anika E. , Bub Achim , Rimbach Gerald , Daniel Hannelore 
Published: November 2023

Background

Trans‐resveratrol (RES) has received considerable interest in biomedical research in the last decade for its attributed health benefits and as a putative “energy restriction mimetic”. However, findings are mainly derived from model organisms including worms, fruit flies, and mice and usually do no take into account that biotransformation of RES may be species‐specific. Knowledge on the biotransformation processes may also explain better the inconsistency of biological data collected on RES.

Aim

To study the metabolism of RES in the different species in a comparative manner

Method

Caenorhabditis elegans (wild‐type N2, variety Bristol), grown for 48 h on NGM agar containing 100 μM RES and heat‐killed bacteria as food, were washed, homogenized and extracted with methanol. Fruit flies (Drosophila melanogaster) of the line w1118 (Bloomington Drosophila Stock Center, #5905) were raised on standard cornmeal‐agar medium supplemented with RES (200 and 500 μM). Flies were kept at a density of 50 animals per vial for at least one week. Male C57BL/6N mice (n=6) were fed a RES supplemented diet for 14 days, killed and blood was collected (German Animal Ethics Committee; ref. no: 55.2‐1‐54‐2532‐22‐11). 6 male healthy men ingested a single dose of a RES containing grapevine shoot extract (0.5 mg RES/mg KG). Blood and urine samples were collected (German Clinical Trials Register as DRKS00004311, Universal Trial Number (WHO) UTN: U1111‐1133–4621). All samples were analyzed under standardised conditions with LC‐DAD‐QToF‐MS/MS. Metabolites were characterized using fragmentation pattern, accurate masses and in part by reference substances.

Results

RES was extensively metabolized in C. elegans as well as in mice, but the metabolite profiles were highly diverse. In C. elegans at least 9 different sugar conjugates with RES‐phosphoglucoside and RES‐3‐glucoside as the predominant metabolites were found. In mice, at least 8 sulfate and glucuronide conjugates of RES and dihydro‐RES, a metabolite formed by the gut microbiota, were detected with dihydro‐RES‐glucuronide and ‐disulfate as the major entities. Only 18% of RES was found as the parent compound in worms and <1% in mice. In Drosophila, essentially the same phosphoglucoside and 3‐O‐glucoside conjugates were found like in C. elegans although the extent of conjugation appeared much lower with the RES aglycone dominating the spectrum. In humans, RES‐3‐sulfate was the main metabolite in plasma 1 h after ingestion whereas in the urine 12–24 h after ingestion dihydro‐RES and lunularin conjugates predominated but with huge interindividual variation.

Conclusion

Significant differences in the biotransformation of RES between the species were observed. In mice and humans the metabolism of RES by the gut microflora is of major importance whereas these processes do not seem to play a role in worms and flies. Mice and humans differ regarding the phase‐II metabolism with huge interindividual differences in humans. Little is known about the biological activities of the various RES metabolites identified which warrants further investigations.