Effect on capillary permeability in rabbits of iridoids from Buddleia scordioides

The methanol soluble fraction of the leaves of Buddleia scordioides after column chromatography resulted in the isolation of two known iridoid glucosides, catalpol and methylcatalpol. The structures were elucidated by extensive 1D-2D-NMR spectroscopy. The structure of methylcatalpol was confirmed by single-crystal x-ray diffraction. These compounds showed protective activity against increased (both chloroform and histamine) skin vascular permeability in rabbits. The protective effect was measured as the reduction in leakage of Evans blue. The results showed that the iridoids produced a significant inhibition of microvascular permeability. A comparison was made between the action of the iridoids and a known inhibitor of vascular permeability, troxerutin (50 mg/kg). Methylcatalpol and catalpol were found to be less effective than troxerutin.