Ectoine is a cyclic amino acid isolated from halophototrophic bacteria of the genus Ectothiorhodospira. Ectoine is a zwitterion which can act as a substrate of the E. coli transporter ProP. Ectoine is cytoprotective, reducing claudin 2 expression in inflammatory bowel disease and inhibiting loss of ZO-1 and occludin and preventing IFN-γ/TNF-α-induced paracellular flux of 4 kDa FITC-dextran in vitro. Ectoine reduces expression of pro-inflammatory cytokines and oxidative stress during colitis.