The constituents of Cibotium barometz and their permeability in the human Caco-2 monolayer cell model

Ethnopharmacological relevance: Cibotium barometz(L)J. Sm. (Dicksoniaceae) has been traditionally used as anti-inflammatory and anodyne. Aim of the study: To investigate the constituents in the rhizomes of Cibotium barometz, and evaluate their permeability in the human Caco-2 model. Materials and methods: The rhizomes extracts of Cibotium, barometz were isolated by chromatographic techniques. Structures of isolated compounds were identified by spectroscopic methods. The permeability of the main constituents was evaluated using human Caco-2 cell monolayer as a model system. Results: Three unusual sesquiterpenes having 1-indanone nucleus (1, 3 and 4) and an unusual orthoester spiropyranosyl derivative of protocatechuic acid (2) were isolated from the rhizomes of Cibotium barometz. Among these, the bilateral permeation of 1, 3 and 4 in Caco-2 model was examined. The apparent permeability coefficients (P-app) of 1 was identical with those of propranolol, which is often used as reference standard of high permeability. The P pp values of 3 and 4 were in agreement with those of atenolol, which is often used as reference standard of poor permeability. The permeation rates of 1, 3 and 4 increased linearly as a function of time up to 180 min and with the concentration within the test range of 25-200 mu M. Conclusions: This is the first report on the presence of compounds 2 and 3 in this plant and 4 was a new compound. Compound 1 is assigned for a well-absorbed, and 2 and 3 are assigned for the poorly absorbed compounds in human intestine. A passive diffusion mechanism for transport of 1, 3 and 4 in Caco-2 model was proposed. The results provided some useful information for predicting the oral bioavailability of 1, 3 and 4. (C) 2009 Elsevier Ireland Ltd. All rights reserved.