Two New Nortriterpenes from Ligularia tongolensis

Abstract

Two new nortriterpenes having a ursane type structure were isolated from the roots of Chinese Ligularia tongolensis, and their structures were elucidated by interpretation of spectral data. Their relative stereochemistries were also clarified by detailed analysis of proton–proton coupling constants and by NOE experiments.

A New Norsesquiterpenoid from the Roots of Ligularia Fischeri

“…This inference was supported by the presence of α,β,αp,βp-unsaturated ketone absorption bands at 1716 and 1649 cm −1 in the IR spectrum. Correlations of the H-atom of a OH group at δ (H) 7.27 (s) with C-6, C-7 and C-8 confirmed the location of OH at C (7). The above discussed analysis of the 1D-and 2D-NMR data of compound 1 provided further evidence for the structure of 1 Fig.…”

“…[1][2][3] Previous phytochemical investigations of Ligularia showed that the main components were eremophilane sesquiterpenes and pyrrolizidine alkaloids with strong physiological activities. [4][5][6][7][8] With the aim of identifying the active constituents from the genus Ligularia, the roots of the perennial herb Ligularia fischeri were investigated. A new norsesquiterpenoid was isolated together with three known compounds.…”

Two new secondary metabolites from the fruits of mangrove Avicennia marina

“…In this communication, the determination of the exact absolute stereochemistry Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 7/30/15 7:31 PM predicted on the basis of the small coupling constant 3 J H3,H4 ( J = 3.0 Hz). Finally, the absolute configurations of C3 and C4, was determined by its CD spectrum, in which a positive Cotton effect by cyclohexene group was show at 205 nm (Δε + 10.2), whereas the reported value for ixero B whose stereostructures of C3 and C4 were determined by CD spectrum, was negative [12]. Although we do not have an explanation for the difference in the absolute values of the Cotton effect, appplicaton of the octant rule to the compound depicted in the formula of 2 found that the expected sign of the Cotton effect should be positive.…”

Triterpenoids

“…394 Other new 28-norursane derivatives include the formate ester cladocalol 550 from Eucalyptus cladocalyx 427 and the 28-norurs-12-ene-2,3,19triols 551 and 552 from Ligularia tongolensis. 428,429 Urs-20-en-16-ol 553, with unspecified stereochemistry at C-16, is a constituent of the maidenhair fern Adiantum capillus-veneris. 430 Nudicaulines A 554 and B 555 have been isolated from Launaea nudicaulis together with urs-11-en-3b-ol and its acetate although they have been drawn as the corresponding taraxastane derivatives in ref.…”