Chemical Constituents from the Roots of Rehmannia glutinosa

Ten secondary metabolites, including one new monoterpene rhamnoside (1), five terpenoids (2-6), two nucleosides (7-8), and two phenylethanoid glycosides (9-10) were isolated from the roots of Rehmannia glutinosa. Their structures were determined by spectroscopic analysis such as NMR and HR-ESI-MS. In the tyrosinase inhibitory assay, compounds 2, 6 and 8 showed inhibition against tyrosinase. Compounds 1, 4, 5, 6, 9 and 10 are being reported in the genus Rehmannia for the first time.