Dihydrophenanthrenes from the stems and leaves ofDioscorea nipponicaMakino

From the CHCl3-soluble portion of the 70% EtOH extract of the stems and leaves of Dioscorea nipponica Makino, two new dihydrophenanthrenes were isolated, 2,7-dihydroxy-3,4,6-trimethoxy-9,10-dihydrophenanthrene, and 4,4',7,7'-tetrahydroxy-2,2',6,6'-tetramethoxy-1,1'-bi-9,10-dihydrophenanthrenyl. The structures were determined by means of HRMS, 1H-NMR, 13C-NMR, and HMBC experiments.