Fig. 4

Active antibiofilm compounds from metabolites of CA in LJF. a Antibiofilm activity of LJF and CA. b Growth curves of bacterial growth at different sub-MICs of CA. c GC–MS analysis of CA at 0.5, 1, 2, 4, 6, 24 h. The red arrow indicates the location of the peak of CA. d Measured ion spectrum (upper) and matched ion spectrum in NIST17 database (lower) of CA. e Metabolic pathways of CA in intestine (left) and liver (right). f In vitro antibiofilm effects of CA and its intestinal metabolites. g In vitro antibiofilm effects of CA and its liver metabolites. h GC–MS analysis of quinic acid at 0.5, 1, 2, 4, 6, 24 h. The red arrow indicates the location of the peak of quinic acid. i Measured ion spectrum (upper) and matched ion spectrum in NIST17 database (lower) of quinic acid. j The antibacterial activity ratio of caffeic acid and quinic acid to CA. k The antibacterial activity ratio of caffeic acid and its main metabolites to CA. l, m The antibacterial activity ratio of quinic acid and its major metabolites to CA. n–o Effects of dihydrocaffeic acid and gallic acid on the integrity (n) and the permeability (o) of bacteria membrane against MRSA. p-q Effects of dihydrocaffeic acid on the integrity (p) and the permeability (q) of bacteria membrane against MSSA. r Effects of quinic acid on EPS secretion in biofilm formation (upper) and in mature biofilm (lower). s–u The synergistic antibiofilm effects of sub-MIC quinic acid with levofloxacin (s), clarithromycin (t) and azithromycin (v). QA: quinic acid. *P < 0.05, **P < 0.01, compared with corresponding control