EFFECT OF CAPSIANOSIDE, A DITERPENE GLYCOSIDE, ON TIGHT-JUNCTIONAL PERMEABILITY

Abstract Previous work (Hashimoto et al., (1994) Biosci. Biotech. Biochem. 58, 1345) revealed that a sweet pepper extract enhanced the tight-junctional (TJ) permeability of a human intestinal Caco-2 cell monolayer. In the present study, the substance which modulated the TJ permeability was chromatographically purified from the extract. The active substances were identified as capsianosides A–F, diterpene glycosides. Treatment of the cells with capsianoside F, the most active compound, decreased the cellular G-actin content by 40% and increased the F-actin content by 16%. The effect of capsianoside F was significantly suppressed by disturbing the cytoskeletal structure with cytochalasin D at a low dose (50 ng/ml). These results suggest that capsianosides affected the cytoskeletal function by modulating the reorganization of actin filaments, by which the TJ structure and permeability were changed. The possible involvement of a PKC inhibition in the mechanism of an increase in TJ permeability is also suggested.