Hypericum sampsonii Hance contains mangiferin, isomangiferin,2-hydroxy-3,4-dimethoxyxanthone, toxyloxanthone B, and a new compound,hyperxanthone, which was identified as 5,9-dihydroxy-3,3-dimethylpyrano- [3,2-a]xanthen-12(3H)-one on the basis of spectroscopic evidences.Characteristic fragment ions in the mass spectrum of pyranoxanthone are discussed.
