Effect of n-butanol fraction of Acacia catechu on transepithelial resistance on monolayer of epithelial cells. A) The effect of n-butanol fraction on Caco-2 epithelial cells monolayer integrity. Plant n-butanol fraction/Nonoxynol-9 (N-9) was added to the apical chamber at t = 0 and transepithelial resistance (TER) readings were measured at 0.5, 1, 2, 4, 8 and 24 h. As toxicity control, N-9 gel (1:50 dilution ~ 0.6 mg/ml) was added to the indicated well. B) The effect of the n-butanol fraction on TER of HEC-1A cells. Values are expressed as mean ± SE of 2 different experiments performed in duplicates.