Fig. 4

DhBBR inhibited TMAO generation by targeting bacterial flavin-containing monooxygenase (FMO) in gut. a Both BBR and dhBBR (0.03, 0.06 mM) inhibited TMAO production in intestinal bacteria (n = 5, ***P < 0.001), and the known FMO inhibitors (imipramine and methimazole) showed an inhibition as well. b The effect of BBR (0.03 mM) on TMAO production in vitro was tested in 15 intestinal bacterial strains, of which TMAO was detected in P. mirabilis, P. aeruginosa, P. anaerobius and E. aerogenes. In P. aeruginosa and P. anaerobius, TMAO showed a decrease after BBR treatment (n = 5, **P < 0.01). c BBR, dhBBR (0.03 mM) and imipramine (inhibitor of FMO, 0.1 mM) decreased TMAO level in P. aeruginosa after incubation for 12 h (n = 6, *P < 0.05, **P < 0.01). d The conversion from TMA to TMAO increased in the FMO-expressed reaction system (pET28a-fmo) after 4 h incubation (n = 4, ***P < 0.001). e BBR and dhBBR (0.06 mM) inhibited the transformation from TMA to TMAO in a heterologously FMO-expressed reaction system (E. coli with pET28a-fmo transformation) at 4 h after incubation (n = 4, *P < 0.05). f The inhibition ration (%) of TMAO production in the FMO-reaction system (in E. coli with pET28a-fmo) was dose-dependent (n = 4). g, h DhBBR (0.06 mM) inhibited the production of TMAO (g) and increased the level of TMA (h) in the FMO-expression reaction system (E. coli pET28a-fmo, n = 6, *P < 0.05, **P < 0.01, ***P < 0.001). i DhBBR was transformed into BBR in the FMO reaction system (E. coli pET28a-fmo), n = 6. Data shown are mean ± SD and analysed with two-tailed student’s t test