Melitidin: a flavanone glycoside from Citrus grandis 'Tomentosa'.

Citrus grandis 'Tomentosa' is a traditional Chinese medicine, used as an antitussive. In this research, melitidin, a flavanone glycoside, was isolated from this species for the first time by using chromatographic methods. The structure was confirmed through comprehensive analyses of its ultraviolet, infrared, 1H and 13C NMR, HMBC and HMQC spectroscopic and high-resolution mass spectrometric data. Meliditin showed a good antitussive effect on cough induced by citric acid in Guinea pig, suggesting that it was a contributor to the antitussive effect of C. grandis 'Tomentosa'.