Objective: To compare the antitussive activity of three kinds of Stemonae Radix specified in the Chinese Pharmacopoeia, including roots of Stemona sessilifolia, S. japonica and S. tuberosa.
Method: The antitussive activity was determined in mouse after cough induction by ammonia aerosol stimulation and the number of cough in 2 min were detected with codeine as positive control.
Result: All the decoctions, the total alkaloid fractions and non-alkaloid fractions of S. sessilifolia, S. japonica and three chemical types of S. tuberosa showed significant antitussive effect and exhibited a dose-dependent inhibition of coughing. The ED50 values showed that the antitussive activity strength for both total alkaloid fractions and the decoctions are: S. tuberosa (Type I) > S. sessilifolia > S. japonica. The total alkaloid fractions had more potent atitussive activity than the decoctions and non-alkaloid fractions. The antitussive activity strength for the three chemical types of S. tuberosa is: Type I > Type III > Type II. The samples from different producing areas for the same species of Stemonae Radix had no significant differences in antitussive activity. The result also showed that the honey-processed slice had much stronger antitussive activity than raw slice.
Conclusion: The antitussive efficacies of Stemonae Radix were influenced by chemical diversity both in same species and among different species, different fractions and processed method.