Project Details
Projekt
Importance and Bioactivity of the Microbial trans-Resveratrol Metabolites Dihydroresveratrol and Lunularin
Subject Area
Nutritional Sciences
Food Chemistry
Food Chemistry
Term
from 2015 to 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 274521263
The stilbene trans-Resveratrol (t-RES) is considered to mimic the positive effects of calorie restriction (CR), which may prevent or reverse the detrimental effects of obesity, type 2 diabetes, hypertension, chronic inflammation and other age-associated metabolic diseases. Orally ingested t-RES is effectively absorbed in the small intestine and strongly metabolized by phase-II-enzymes and by the gut microbiota. In own preliminary studies, next to dihydroresveratrol (DH-RES), two previously unknown microbial t-RES metabolites, i.e. 3,4´-dihydroxy-trans-stilbene and lunularin, were identified in vitro and in vivo. However, strong inter-individual differences in the profile of microbial metabolites occurred (lunularin-producers vs. non-lunularin-producers). However, bacterial lunularin producers are currently unknown. The preliminary human intervention study was performed with a limited number of volunteers (n=12). In addition, little is known about the bioactivity of the microbial metabolites. Our results in HCT116 cells indicate that DH-RES and lunularin differ in their effects on various molecular targets. We therefore hypothesize that conflicting results reported with regard to the beneficial effects of t-RES on lifespan could be caused (at least in part) by the microbial metabolism of t-RES. The objectives of this project are 1.) elucidation of the importance of the microbial t-RES metabolites dihydroresveratrol and lunularin in human adults by means of a human intervention study that is based on a larger cohort (n=100; LC-DAD-MS-analysis of 48 h-urine); 2.) identification of bacterial species which are associated with the formation of lunularin using 16S rRNA high-throughput sequencing, DGGE and qRT-PCR. In addition, lunularin-producing bacteria will be isolated from human faecal samples and subsequently identified; 3.) identification of differences in biological properties of t-RES, DH-RES and lunularin in a mouse model (intraperitoneal injection and feeding, 10 groups à 10 animals). The following CR-related parameters will be investigated in vivo: energy expenditure by indirect calorimetry and body composition by magnet NMR minispec. Murine plasma and urine samples will be analysed as follows: insulin-like growth factor and insulin by ELISA; cholesterol and triglyceride levels by photometry; the expression of Nrf2 target genes GPx, HO-1, GST and NQO1 by Western blotting and qRT-PCR; the activity of AMPK by Western blotting, the Sirt1 activity by fluorimetry and autophagy-markers by Western blotting anti-LC3; LC-MS and comprehensive GCxGC-MS based metabolomics. The investigations described here are anticipated to provide powerful new data to elucidate the importance of lunularin and DH-RES as microbial t-RES metabolites in humans and to assess the impact of microbial t RES metabolism on the CR-mimetic properties of this stilbene.
DFG Programme
Research Grants
