Triterpene Glycosides of Scheffleropsis angkae. IV. Structure of Glycosides L-C2 and L-I2

Two new triterpene glycosides of the -amyrin series, L-C ₂ and L-I ₂ , 27-hydroxyursolic acid 3-O--L-arabinopyranoside and its 28-O--L-rhamnopyranosyl-(14)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl ester, are isolated from leaves ofScheffleropsis angkae(Araliaceae). The structures of the glycosides are established using chemical methods and NMR techniques ( ¹ H, ¹³ C, ¹³ C-APT, COSY, TOCSY, HSQC, HMBC, and ROESY).     

PURIFICATION OF GINKGO LEAVES EXTRACT WITH MACROPOROUS ADSORBENT BASED ON UREA-FORMALDEHYDE CONDENSED POLYMERS

I INTRODUCTIONGinkgo biloba L. is one of the important economic trees, which is widely distributed inChina. In recent years, medicinal and healthful preparations based on the extractS from ginkgoleaves have been rapidly developed for the treatment of peripheral circulatory and cerebralinsufficiencyl']. Such eXtracts contain flavonol glycosides and terpene lactones as thepharmacologically active compounds. Organic-solvent extraction is one of the earliest methodsto prepare the extracts o…     

A new hydroxybenzoic acid glycosides from the plant of Trifolium lupinaster

<正>A new 5-O-(β-D-glucopyranosyl)-6'-O-benzoyl-2,5-dihydroxybenzoic acid was isolated from the ethyl acetate extract from the whole plants of Trifolium lupinaster L.Its structure was determined and deduced on the basis of their spectral data.     

A New Cardenolide and Two New Pregnane Glycosides from the Root Barks of Periploca sepium

A new cardenolide and two new pregnane glycosides, periplogenin 3‐[O‐β‐glucopyranosyl‐(1→4)‐β‐sarmentopyranoside] ( 1 ), (3β,20S)‐pregn‐5‐ene‐3,17,20‐triol 20‐[O‐β‐glucopyranosyl‐(1→6)‐O‐glucopyranosyl‐(1→4)‐β‐canaropyranoside] ( 2 ), and (3β,14β,17α)‐3,14,17‐trihydroxy‐21‐methoxypregn‐5‐en‐20‐one 3‐[O‐β‐oleandropyranosyl‐(1→4)‐O‐β‐cymaropyranosyl‐(1→4)‐β‐cymaropyranoside] ( 3 ), were isolated from the root barks of Periploca sepium Bge , together with seven related known compounds, periplogenin, xysmalogenin, (3β,20S)‐pregn‐5‐ene‐3,17,20‐triol, (3β,14β,17α)‐3,14,17‐trihydroxy‐21‐methoxypregn‐5‐en‐20‐one, (3β,20S)‐pregn‐5‐ene‐3,20‐diol 3‐β‐glucopyranoside 20‐β‐glucopyranoside, (3β,20S)‐pregn‐5‐ene‐3,20‐diol 3‐[O‐2‐O‐acetyl‐β‐digitalopyranosyl‐(1→4)‐β‐cymaropyranoside] 20‐[O‐β‐glucopyranosyl‐(1→6)‐O‐β‐glucopyranosyl‐(1→2)‐β‐digitalopyranoside], and (3β,20S)‐ pregn‐5‐ene‐3,20‐diol 20‐[O‐β‐glucopyranosyl‐(1→6)‐β‐glucopyranoside]. Their structures were elucidated on the basis of spectroscopic analyses.     

Glycosidic Constituents of Celastrus orbiculatus

Three new, 1 – 3 , and seven known phenolic and terpenic glycosides were isolated from the BuOH‐soluble fraction of 95% EtOH extract of the roots and rhizomes of Celastrus orbiculatus. The structures of the new compounds were elucidated as carvacrol 2‐O‐α‐L ‐rhamnopyranosyl‐(1→6)‐β‐D ‐glucopyranoside ( 1 ), 5‐methoxycarvacrol 2‐O‐α‐L ‐rhamnopyranosyl‐(1→6)‐β‐D ‐glucopyranoside ( 2 ), and 15‐hydroxytorreyol 10‐O‐β‐D ‐apiofuranosyl‐(1→6)‐β‐D ‐glucopyranoside ( 3 ) on the basis of spectroscopic analysis and chemical methods.     

Presenegenin Glycosides from Securidaca welwitschii

The five new presenegenin glycosides 1 – 5 were isolated from Securidaca welwitschii, together with one known sucrose diester. Compounds 1 – 4 were obtained as pairs of inseparable (E)/(Z)‐isomers of a 3,4‐dimethoxycinnamoyl derivative, i.e., 1 / 2 and 3 / 4 . Their structures were elucidated mainly by 2D‐NMR techniques and mass spectrometry as 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐{O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[β‐D ‐glucopyranosyl‐(1→3)]‐4‐O‐[(E)‐3,4‐dimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 1 ) and its (Z)‐isomer 2 , 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐{O‐β‐D ‐galactopyranosyl‐(1→4)‐O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐3‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[β‐D ‐glucopyranosyl‐(1→3)]‐4‐O‐[(E)‐3,4‐dimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 3 ) and its (Z)‐isomer 4 , and 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐[O‐β‐D ‐galactopyranosyl‐(1→3)‐O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐β‐D ‐fucopyranosyl] ester ( 5 ) (presenegenin=(2β,3β,4α)‐2,3,27‐trihydroxyolean‐12‐ene‐23,28‐dioic acid).     

Cyclic voltammetry of nitrophenyl N‐glycosides on mercury electrode

Ten nitrophenyl N‐glycosides have been studied electrochemically in neutral (at pH 7) water–organic solutions by cyclic voltammetry using static mercury drop electrode. For all compounds under investigation the two electrochemical processes have been observed: the four‐electron irreversible reduction of their nitro groups to the corresponding phenylhydroxylamine derivatives, as well as the two‐electron quasi‐reversible process between phenylhydroxylamine and nitroso derivatives. For three compounds the additional electrochemical processes have been also observed, which can be connected with the formation of azoxybenzene derivatives. The potentials of both redox processes: a two‐electron quasi‐reversible R? NHOH/R? NO (E_f) and four‐electron irreversible R? NO₂/R? NHOH (E_pc(I)) systems have been determined and discussed according to crystal structures of selected compounds. E_f and E_pc(I) depended strongly on the positive mesomeric effect (caused by glycosidic nitrogen atom), as well as on the intramolecular hydrogen bond between electroactive nitro group and the hydrogen atom at the glycosidic atom observed in N‐o‐nitrophenyl‐2,3,4,6‐tetra‐O‐acetyl‐β‐D ‐glucopyranosylamine. Moreover, the chirality of selected reactants has had the pronounced effect on the E_pc(I). Copyright © 2011 John Wiley & Sons, Ltd.