Glucosinolate and Desulfo-glucosinolate Metabolism by a Selection of Human Gut Bacteria.
Glucosinolate (GSL) hydrolysis is mediated by the enzyme myrosinase which together with specifier proteins can give rise to isothiocyanates (ITCs), thiocyanates, and nitriles (NITs) in cruciferous plants. However, little is known about the metabolism of GSLs by the human gut flora. The aim of the work was to investigate the metabolic fates of sinigrin (SNG), glucotropaeolin (GTP), gluconasturtiin (GNT), and their corresponding desulfo-GSLs (DS-GSLs). Three human gut bacterial strains, Enterococcus casseliflavus CP1, Lactobacillus agilis R16, and Escherichia coli VL8, were chosen for this study. GNT was metabolized to completion within 24 h to phenethyl ITC and phenethyl NIT (PNIT) by all bacteria, except for L. agilis R16 which produced only PNIT. At least 80 % of GTP and SNG were metabolized by all bacteria within 24 h to the corresponding ITCs and NITs. The pH of media over time gradually became acidic for both L. agilis R16 and E. coli VL8, while for E. casseliflavus CP1 the media became slightly alkaline with NIT and ITC production occurring between pH 3.0 and 7.5. ITC production peaked between 4 and 10 h in most cases and gradually declined while NIT production increased and remained relatively constant over time. The total percentage products accounted for 3-53 % of the initial GSL. NITs were produced from DS-GSLs suggesting an alternative metabolism via desulfation for the food based GSLs. The metal ion dependency for NIT production for GNT and its DS form was investigated where it was shown that Fe(2+) increased NIT production, while Mg(2+) stimulated the formation of ITC.
Faculty of Life Sciences, Imperial College London, Exhibition Rd, London, SW7 2AZ, UK. vijitra.l@msu.ac.th.|Natural Antioxidant Research Unit, Department of Biotechnology, Faculty of Technology, Mahasarakham University, Khamriang, Kantarawichai, Mahasarakham, 44150, Thailand. vijitra.l@msu.ac.th.
Vijitra
V
Luang-In
Faculty of Life Sciences, Imperial College London, Exhibition Rd, London, SW7 2AZ, UK.|Microbiology Section, Department of Plant Science, Faculty of Science, University of Sebha, PO Box 18758, Sebha, Libya.
Abdulhadi Ali
AA
Albaser
Gut Health and Food Safety Programme, Institute of Food Research, Colney Lane, Norwich, NR4 7UA, UK.
Carmen
C
Nueno-Palop
Faculty of Life Sciences, Imperial College London, Exhibition Rd, London, SW7 2AZ, UK.
Mark H
MH
Bennett
Gut Health and Food Safety Programme, Institute of Food Research, Colney Lane, Norwich, NR4 7UA, UK.
Arjan
A
Narbad
Faculty of Life Sciences, Imperial College London, Exhibition Rd, London, SW7 2AZ, UK.
John T
JT
Rossiter
D016983:Enterococcus / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D000069196:Gastrointestinal Microbiome; D005961:Glucosinolates / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007778:Lactobacillus / Q000378:metabolism*
D005961:Glucosinolates