C14-polyacetylenol glycosides from the roots of Codonopsis pilosula
Eight new C14-polyacetylenol glycosides, containing ene-diyne and ene-yn-ene chromophores named codonopilodiynosides H-M (1–6) and codonopiloenynenosides A and B (7 and 8), respectively, together with three known analogs lobetyolinin, pratialin B, and lobetyolin (9–11), were isolated from an aqueous extract of the roots of Codonopsis pilosula. Their structures were determined by spectroscopic and chemical methods including 2D NMR data analysis and enzymatic hydrolysis. The absolute configurations of aglycones in 1–10 were assigned by application of the methoxyphenylacetic acid (MPA) determination rule of ΔδRS values and/or the empirical rule of Mo2(OAc)4-induced circular dichroism for the vicinal diols, or by comparison of specific rotation values with those of reported compounds. Compounds 4–6 are the first polyacetylenol glycosides possessing a cis-ene-diyne chromophore from the genus Codonopsis, while 8 has a rear trans-ene-yn-cis-ene chromophore and a (6S,7S)-6,7-diol unit against a (6R,7R)-6,7-diol unit in the others. The absolute configurations of lobetyolinin (9) and pratialin B (10) were determined for the first time.