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.