Chemical Constituents from the Roots of Schnabelia tetradonta

Abstract

The new rearranged‐abietane diterpene 1, the four new triterpenoids 2–5, and the new aminoethylphenyl oligoglycoside 6, besides 19 known compounds, were isolated from the roots of Schnabelia tetradonta, a Chinese endemic herb. The structures of the new compounds were elucidated on the basis of spectroscopic evidence as 12,17‐epoxy‐11,14,16‐trihydroxy‐17(15→16)‐abeo‐abieta‐8,11,13,15‐tetraen‐7‐one (1), 21β‐(β‐D‐glucopyranosyloxy)‐2α,3α‐dihydroxyolean‐12‐en‐28‐oic acid (2), 2β,3β,16β‐trihydroxy‐15‐oxo‐28‐norolean‐12‐en‐23‐oic acid (3), 3β‐[(4‐O‐acetyl‐β‐D‐glucopyranuronosyl)oxy]‐2β,16β‐dihydroxy‐28‐norolean‐15‐oxo‐12‐en‐23‐oic acid (4), 3β‐[(4‐O‐acetyl‐6‐O‐methyl‐β‐D‐glucopyranuronosyl)oxy]‐2β,16β‐dihydroxy‐15‐oxo‐28‐norolean‐12‐en‐23‐oic acid (5), and 4‐[2‐(acetylamino)ethyl]phenyl O‐6‐O‐[(Z)‐p‐methoxycinnamoyl]‐β‐D‐glucopyranosyl‐(1→2)]‐O‐[β‐D‐glucopyranosyl‐(1→3)]‐4‐O‐acetyl‐α‐L‐rhamnopyranoside (6), respectively.

Structural characterization of aminoethylphenyl oligoglycosides in Schnabelia tetradonta

“…For example, cleavage of the methylated coumaroyl group with the transfer of a hydrogen atom formed the ion at m / z 712, and cleavage of the glucosidic bond formed the ion at m / z 533 in the MS 3 spectrum. Unlike compounds 1 and 1a , the MS 4 experiment using the fragment at m / z 533 produced an abundant fragment ion at m / z 345, attributed to cleavage adjacent to the monoacetylated rhamnose group; this interpretation was also supported by our previous finding that 2a was a monoacetylated derivative of 1a 5. In addition, elimination of acetic acid from the ions at m / z 695 and 533 formed the ions at m / z 635 and 473, respectively (Scheme ).…”

“…In conclusion, it is worth emphasizing that the information elucidated from the mass spectra recorded with application of ESI‐MS n , combined with HPLC and UV spectroscopy, permitted identification of the hitherto unidentified compounds in S. tetradonta as 1‐ O ‐[6‐ O ‐( E )‐ p ‐methoxycinnamoyl‐ β ‐ D ‐glucopyranosyl‐(1 → 2)]‐[ β ‐ D ‐glucopyranosyl(1 → 3)]‐ α ‐ L ‐rhamnopyranoside ( 1 ) and 4‐[2‐(acetylamino)ethyl]phenyl O ‐6‐ O ‐[( E )‐ p ‐methoxycinnamoyl]‐ β ‐ D ‐glucopyranosyl(1 → 2)‐ O ‐[ β ‐ D ‐glucopyranosyl‐(1 → 3)]‐4‐ O ‐acetyl‐ α ‐ L ‐rhamnopyranoside ( 2 ), i.e., as the ( Z )‐isomers of the previously identified3,5 compounds 1a and 2a , respectively. Thus, without the need for phytochemical isolation or elaborate sample preparation, novel aminoethylphenyl oligoglycosides were rapidly characterized and identified by ESI‐MS n , although NMR was necessary to confirm the structures of these compounds.…”

“…The latter, commonly called ‘Jin Gu Cao’, is used as a febrifuge to relieve internal fevers and as a remedy treatment for rheumatism in traditional Chinese medicine 1. To date, there are few chemical constituents reported for this plant except for our work in searching for new biological active components in S. tetradonta 2–5. In our previous study we reported that two aminoethylphenyl oligoglycosides had been isolated from S. tetradonta ,3,5 and their structures were elucidated as 4‐acetylaminoethylphenyl 1‐ O ‐[6‐ O ‐( Z )‐ p ‐methoxycinnamoyl‐ β ‐ D ‐glucopyranosyl‐(1 → 2)]‐[ β ‐ D ‐glucopyranosyl(1 → 3)]‐ α ‐ L ‐rhamnopyranoside ( 1a ) and 4‐[2‐(acetylamino)ethyl]phenyl O ‐6‐ O ‐[( Z )‐ p ‐methoxycinnamoyl]‐ β ‐ D ‐glucopyranosyl(1 → 2)]‐ O ‐[ β ‐ D ‐glucopyranosyl‐(1 → 3)]‐4‐ O ‐acetyl‐ α ‐L‐rhamnopyranoside ( 2a ), based on 1 H, 13 C NMR, 2D‐NMR and HR‐ESIMS.…”

“…Sample I, containing 1 and 1a , and sample II, containing 2 and 2a , were isolated from S. tetradonta , purified on a C 18 cartridge, and eluted with methanol/water; this eluant was subsequently used for HPLC/UV‐MS analysis. Compounds 1a and 2a were available from a previous study 3,5…”

Phenolic Compounds from Selaginella moellendorfii

“…Part of the structure of 6 was similar to the known lignan, isolated from the same plant, (À)-secoisolariciresinol (15) [18], which was considered as the precursor of 6. The signal at d(H) 3.34 -3.39 (m) in the 1 H-NMR spectrum of 6 was attributed to H a ÀC(9) and H b ÀC (9). The singlet at d(H) 3.68 (s, 6 H) corresponded to two MeO groups.…”