A novel xanthine alkaloid and two known flavonoids have been isolated from the leaves of Bosistoa floydii and identified as 1,3-di(3-methylbut-2-enyl)-7-methylxanthine 5,4'-dihydroxy-3,7,3'-trimethoxyflavone and 5-hydroxy-3,3',4',5',7-pentamethoxyflavone.