6-O-α-L-Rhamnopyranosylcatalpol Derivative Iridoids from Verbascum cilicicum

From the aerial parts of Verbascum cilicicum Boiss., 6 iridoid glycosides, namely catalpol (1), verbaspinoside [= 6-O-(2″-O-trans-cinnamoyl)-α- L-rhamnopyranosylcatalpol] (2), 6-O-(3″-O-trans-cinnamoyl)-α-L- rhamnopyranosylcatalpol (3), 6-O-(4″-O-trans-cinnamoyl)-α-L- rhamnopyranosylcatalpol (4), saccatoside [= 6-O-(2″-O-trans-p-coumaroyl)- α-L-rhamnopyranosylcatalpol] (5), and 6-O-(3″-O-trans-p-coumaroyl)- α-L-rhamnopyranosylcatalpol (6), were isolated. The structures of the compounds were elucidated by means of 1 and 2 dimensional (DQF-COSY, HMQC and HMBC) NMR techniques and LC-ESIMS.