Glucosinolate and Desulfo-glucosinolate Metabolism by a Selection of Human Gut Bacteria
- 566 Downloads
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 Fe2+ increased NIT production, while Mg2+ stimulated the formation of ITC.
KeywordsSulforaphane AITC Sinigrin PITC Nutrient Broth Medium
The authors wish to acknowledge the Royal Thai Government for Scholarship awarded to VL and the UK Biotechnology and Biological Sciences Research Council (BB/J004545/1) for partial financial support of this research.
Compliance with Ethical Standards
Conflicts of interest
The authors declare that they have no conflicts of interest.
- 16.Getahun SM, Chung FL (1999) Conversion of glucosinolates to isothiocyanates in humans after ingestion of cooked watercress. Cancer Epidemiol Biomark Prev 8:447–451Google Scholar
- 17.Hanschen FS, Brueggemann N, Brodehl A, Mewis I, Schreiner M, Rohn S, Kroh LW (2012) Characterization of products from the reaction of glucosinolate-derived isothiocyanates with cysteine and lysine derivatives formed in either model systems or broccoli sprouts. J Agric Food Chem 60:7735–7745CrossRefPubMedGoogle Scholar
- 25.Luang-In V, Rossiter JT (2015) Stability studies of isothiocyanates and nitriles in aqueous media. Songklanakarin J Sci Technol 37:625–630Google Scholar
- 27.Luciano FB, Holley RA (2011) Bacterial degradation of glucosinolates and its influence on the growth of E. coli 0157:H7. Fleischwirtsch Int 1:78–81Google Scholar
- 33.Nallasamy P, Si H, Babu PVA, Pan D, Fu Y, Brooke EAS, Shah H, Zhen W, Zhu H, Liu D, Li Y, Jia Z (2014) Sulforaphane reduces vascular inflammation in mice and prevents TNF-alpha-induced monocyte adhesion to primary endothelial cells through interfering with the NF-kappa B pathway. J Nutr Biochem 25:824–833CrossRefPubMedPubMedCentralGoogle Scholar
- 41.Tani N, Ohtsuru M, Hata T (1974) Studies on bacterial myrosinase. 1. Isolation of myrosinase producing microorganism. Agric Biol Chem 38:1617–1622Google Scholar
- 42.Tanil H, Higashi T, Nishimura F, Higuchi Y, Saijoh K (2008) Effects of cruciferous allyl nitrile on phase 2 antioxidant and detoxification enzymes. Med Sci Monit 14:BR189–BR192Google Scholar
- 43.Thies W (1988) Isolation of sinigrin and glucotropaeolin from cruciferous seeds. Fett Wiss Technol Fat Sci Technol 90:311–314Google Scholar
- 48.Uda Y, Kurata T, Arakawa N (1986) Effects of ph and ferrous ion on the degradation of glucosinolates by myrosinase. Agric Biol Chem 50:2735–2740Google Scholar