Turpinionosides A-E: megastigmane glucosides from leaves of Turpinia ternata Nakai.

From leaves of Turpenia ternata (Staphylaceae), one megastigmane and seven of its glucosides (1-8) were isolated. Megastigmane and two of the glucosides were found to be known compounds, namely, 3S,5R,6R,9S-tetrahydroxymegastigmane (1), corchoionoside C (2), and icariside B4 (3). The structures of compounds 4-8 (turpinionosides A-E, respectively) were elucidated by means of spectroscopic analyses, and then their absolute structures were determined by the modified Mosher's method to be (3S,5R,6S,9S)-3,6,9-trihydroxymegastigman-7-ene 3-O- and 9-O-beta-D-glucopyranosides (4, 5, respectively), (1S,3S,5R,6S,9R)-3,9,12-trihydroxymegastigmane 3-O-beta-D-glucopyranoside (6), (3S,4R,9R)-3,4,6-trihydroxymegastigman-5-ene 3-O-beta-D-glucopyranoside (7), and (2S,9R)-2,9-dihydroxymegastigman-5-en-4-one 2-O-beta-D-glucopyranoside (8).