AUTHOR=Ladurner Angela , Zehl Martin , Grienke Ulrike , Hofstadler Christoph , Faur Nadina , Pereira Fátima C. , Berry David , Dirsch Verena M. , Rollinger Judith M. TITLE=Allspice and Clove As Source of Triterpene Acids Activating the G Protein-Coupled Bile Acid Receptor TGR5 JOURNAL=Frontiers in Pharmacology VOLUME=8 YEAR=2017 URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2017.00468 DOI=10.3389/fphar.2017.00468 ISSN=1663-9812 ABSTRACT=
Worldwide, metabolic diseases such as obesity and type 2 diabetes have reached epidemic proportions. A major regulator of metabolic processes that gained interest in recent years is the bile acid receptor TGR5 (Takeda G protein-coupled receptor 5). This G protein-coupled membrane receptor can be found predominantly in the intestine, where it is mainly responsible for the secretion of the incretins glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). The aim of this study was (i) to identify plant extracts with TGR5-activating potential, (ii) to narrow down their activity to the responsible constituents, and (iii) to assess whether the intestinal microbiota produces transformed metabolites with a different activity profile. Chenodeoxycholic acid (CDCA) served as positive control for both, the applied cell-based luciferase reporter gene assay for TGR5 activity and the biotransformation assay using mouse fecal slurry. The suitability of the workflow was demonstrated by the biotransformation of CDCA to lithocholic acid resulting in a distinct increase in TGR5 activity. Based on a traditional Tibetan formula, 19 plant extracts were selected and investigated for TGR5 activation. Extracts from the commonly used spices