$6-O-alpha-L$-rhamnopyranosylcatalpol derivative iridoids from Verbascum cilicicum

Abstract

From the aerial parts of Verbascum cilicicum Boiss., 6 iridoid glycosides, namely catalpol (1), verbaspinoside [= 6-0-(2"-O-trans-cinnamoyl)-$alpha$-L-rhamnopyranosylcatalpol] (2), 6-0-(3"-O-trans-cinnamoyl)-$alpha$-L-rhamnopyranosylcatalpol (3), 6-0-(4"-O-trans-cinnamoyl)-$alpha$-L-rhamnopyranosylcatalpol (4), saccatoside [= 6-O-(2''-O-trans-p-coumaroyl)-$alpha$-L-rhamnopyranosylcatalpol] (5), and 6-O-(3"-0-trans-p-coumaroyl)-$alpha$-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.