Abstract
Baicalein, berberine, curcumin and hesperidin are the major components derived from Scutellaria baicalensis, Coptis japonica, Curcuma longa and Poncirus trifoliata, respectively. These plants have been used for the treatment of diverse chronic inflammatory diseases including respiratory disease in oriental medicine and their respective major components were reported to have various biological effects including anti-inflammatory activity. In the present study, we investigated whether these four natural products affect mucin release from airway goblet cells and compared the possible activities of these agents with the inhibitory action on mucin release by PLL and the stimulatory action by ATP. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using 3H-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on 3H-mucin release. The results were as follows: (i) baicalein did not affect mucin release significantly; (ii) berberine, curcumin and hesperidin increased mucin release at the highest concentration (10 - 4 M); (iii) PLL inhibited and ATP increased mucin release. We conclude that berberine, curcumin and hesperidin can increase mucin release by directly acting on airway mucin-secreting cells and suggest that these agents be further studied for possible use as mild expectorants during the treatment of chronic airway diseases. Abbreviations. PLL:poly- L-lysine ATP:adenosine triphosphate HTSE:hamster tracheal surface epithelial DMSO:dimethylsulfoxide IL-12:interleukin-12 PBS:phosphate-buffered saline
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