A new 3,28-bidesmosidic triterpenoid saponin was isolated from the ethanolic extract of the root of Dipsacus asperoides C.Y. Cheng et T.M.Ai and its structure established as 3-O-[α-L-rhammopyranosyl(1→3)][-β-D-glycopranosyl(1→4)]-β-D-glycopranosyl(1→3)-α-L-rhammopyranosyl(1→2)-α-L-arabinopyranosyl-hederagenin-28-O-β-D-glycopranosyl(1→6)-β-D-glycopranoside. The results obtained showed that the chemical structure of oligosaccharide chains of the saponin could be elucidated by the combination of 1D - SEMDY, NOE difference spectroscopy in rotating frame and selective long-range DEFT techniques, without having recourse to chemical degration or modification. Complete assignments of severely overlapping proton resonance of the sugar residues were made.

3, 28-bidesmosidic triterpenoid saponin, structural determination of oligosaccharide chains, NOE difference spectroscopy, selective long-range DEPT, 1D-SEMDY

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6	C7	C8	C9	C10	C11	C12	C13	C14	C15	C16	C17	C18	C19	C20	C21	C22	C23	C24	C25	C26	C27	C28	C29	C30
3,2,3,3	aLRhap
3,2,3,4	bDGlcp
3,2,3	bDGlcp
3,2	aLRhap
3	aLArap
28,6	bDGlcp
28	bDGlcp
	xXHederagenin	39.12	26.43	82.72	43.61	47.63	18.42	32.64	39.94	48.26	36.91	23.71	122.93	144.19	42.15	28.36	23.71	46.67	41.67	46.23	30.76	33.17	34.01	63.94	14.20	16.27	17.56	26.09	176.56	32.55	23.71


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6	H7	H8	H9	H10	H11	H12	H13	H14	H15	H16	H17	H18	H19	H20	H21	H22	H23	H24	H25	H26	H27	H28	H29	H30
3,2,3,3	aLRhap
3,2,3,4	bDGlcp
3,2,3	bDGlcp
3,2	aLRhap
3	aLArap	5.00	4.52	3.99	4.10	3.64-4.20
28,6	bDGlcp
28	bDGlcp
	xXHederagenin	1.03-1.58	2.02-2.32	4.28	-	1.69	1.34-1.67	1.21-1.58	-	1.74	-	1.91	5.40	-	-	1.08-2.26	1.88-2.01	-	3.17	1.18-1.67	-	1.08-1.28	1.65-1.85	3.66-4.26	0.90	0.96	1.10	1.17	-	0.85	0.86


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6	C7/H7	C8/H8	C9/H9	C10/H10	C11/H11	C12/H12	C13/H13	C14/H14	C15/H15	C16/H16	C17/H17	C18/H18	C19/H19	C20/H20	C21/H21	C22/H22	C23/H23	C24/H24	C25/H25	C26/H26	C27/H27	C28/H28	C29/H29	C30/H30
3,2,3,3	aLRhap
3,2,3,4	bDGlcp
3,2,3	bDGlcp
3,2	aLRhap
3	aLArap	NMR TSV error 2: unequal length of 13C and 1H datasets
28,6	bDGlcp
28	bDGlcp
	xXHederagenin	39.12/1.03-1.58	26.43/2.02-2.32	82.72/4.28		47.63/1.69	18.42/1.34-1.67	32.64/1.21-1.58		48.26/1.74		23.71/1.91	122.93/5.40			28.36/1.08-2.26	23.71/1.88-2.01		41.67/3.17	46.23/1.18-1.67		33.17/1.08-1.28	34.01/1.65-1.85	63.94/3.66-4.26	14.20/0.90	16.27/0.96	17.56/1.10	26.09/1.17		32.55/0.85	23.71/0.86

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

C[C@@H]1O[C@@H](O[C@H]2[C@H](O[C@H]3CC[C@@]4(C)[C@@H](CC[C@]5(C)[C@@H]4CC=C4[C@@H]6CC(C)(C)CC[C@]6(C(=O)O[C@@H]6O[C@H](CO[C@@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@H]7O)[C@@H](O)[C@H](O)[C@H]6O)CC[C@]45C)[C@]3(C)CO)OC[C@H](O)[C@@H]2O)[C@H](O)[C@H](O[C@@H]2O[C@H](CO)[C@@H](O[C@@H]3O[C@H](CO)[C@@H](O)[C@H](O)[C@H]3O)[C@H](O[C@@H]3O[C@@H](C)[C@H](O)[C@@H](O)[C@H]3O)[C@H]2O)[C@H]1O

1545.673 g/mol (C₇₁H₁₁₆O₃₆)

A new triterpenoid saponin was isolated from the ethanolic extract of the root of Dipsacus asperoides C. Y. Cheng et T. M. A. The structure was elucidated as 3-O-α-L-rhamnopyranosyl (1→3)-β-D-glycopyranosyl (1→3)-α-L-rhamnopyranosyl (1→2)-β-L-arabinopyranosyl-hederagenin. In the present study, 1D-SEMDY in combination with triple irradiation NOE difference spectroscopy has been successfully used for determining the glycosidation position in an aglycome moiety and the sequence of sugar moiety in the compound 1. The results obtained showed that the efficiency of magnetization transfer among the sugar residue of glycoside is much better for 1D-SEMDY than that for conventional 1D-HOHAHA and 1D-multiple relay COSY experiments. For example, for sugar residues such as arabinose which have coupling of 1~1.5 Hz between 4-H and 5-H proton, complete 1H NMR subspectra can be obtained. This technique provides the possibility to acquire pure-phase subspectra without the use of the Z-filter, thus allowing for identification of individual sugar components and spectra assignments in complex overlapping proton spectra. Triple irradiation NOE Difference Spectroscopy is based on the simultaneous irradiation of both lines in a doublet of the sugar anomeric proton with a low decoupling power during the preirradiation time, by which SPT and Bloch-Siegert shift effects can be removed from difference spectra.

structural determination of oligosaccharide chains, 1D-SEMDY, selective 1H NMR techniques, triple irradiation NOE difference spectroscopy, 1H MMR subspectra

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6	C7	C8	C9	C10	C11	C12	C13	C14	C15	C16	C17	C18	C19	C20	C21	C22	C23	C24	C25	C26	C27	C28	C29	C30
3,2,3,3	aLRhap
3,2,3	bDGlcp
3,2	aLRhap
3	bLArap
	xXHederagenin	39.02	26.37	81.19	43.53	47.52	18.09	32.74	39.73	48.16	36.87	23.78	122.88	144.29	42.14	28.30	23.36	46.99	41.74	46.19	30.74	33.95	32.45	63.90	14.09	16.18	17.54	26.06	180.26	33.15	23.66


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,2,3,3	aLRhap	6.18	4.72	4.55	4.30	4.94	?
3,2,3	bDGlcp	5.38	4.03	4.37	4.14	3.90	4.28-4.43
3,2	aLRhap	6.19	4.94	4.78	4.40	4.64	?
3	bLArap	5.02	4.49	3.89	4.11	3.64-4.21
	xXHederagenin


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,2,3,3	aLRhap	NMR TSV error 2: unequal length of 13C and 1H datasets
3,2,3	bDGlcp	NMR TSV error 2: unequal length of 13C and 1H datasets
3,2	aLRhap	NMR TSV error 2: unequal length of 13C and 1H datasets
3	bLArap	NMR TSV error 2: unequal length of 13C and 1H datasets
	xXHederagenin	NMR TSV error 2: unequal length of 13C and 1H datasets

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

C[C@@H]1O[C@@H](O[C@@H]2[C@@H](O)[C@@H](O)CO[C@@H]2O[C@H]2CC[C@@]3(C)[C@@H](CC[C@]4(C)[C@@H]3CC=C3[C@@H]5CC(C)(C)CC[C@]5(C(=O)O)CC[C@]34C)[C@]2(C)CO)[C@H](O)[C@H](O[C@@H]2O[C@H](CO)[C@@H](O)[C@H](O[C@@H]3O[C@@H](C)[C@H](O)[C@@H](O)[C@H]3O)[C@H]2O)[C@H]1O

1059.25 g/mol (C₅₃H₈₆O₂₁)

Two new saponins containing five sugars have been isolated from the ethanol extract of the root of Dipsocus japonicus and their structures established as (3-O-α-L-rhamnopyranosyl(1→3)- α-D-glycopyranosyl(1→3)-α-L-rhamnopyranosyl(1→2）-α-L-arabinopyranosyl-hederagenin-28-O-α-D-glycopyranoside(1) and 3-O-α-D-glycopyranosyl(1→4)[α-L-rhamnopyranosyl(1→3)]-α-D-glycopyranosyl(1→3)-α-L-rhamnopyranosyl(1→2)-α-L-arabinopyranosyl-oleanoic acid (2). Two new NMR techniques, 1D-SEMDY and NOE difference spectroscopy in rotating frame have been successfully used to determine the chemical structure of oligosaccharide chains of the saponins. The results obtained showed that the sites of glycosylation and the sequence of sugars in the saponins can be determined unambiguously and total assignment of severely overlapping proton resonance of sugar residues were achieved, without having recourse to chemical degration or modification.

structural determination of oligosaccharide chains, 1D-SEMDY, Dipsocus japonicus, ROE difference spectroscopy

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

C[C@@H]1O[C@@H](O[C@H]2[C@H](O[C@H]3CC[C@@]4(C)[C@@H](CC[C@]5(C)[C@@H]4CC=C4[C@@H]6CC(C)(C)CC[C@]6(C(=O)O[C@H]6O[C@H](CO)[C@@H](O)[C@H](O)[C@H]6O)CC[C@]45C)[C@]3(C)CO)OC[C@H](O)[C@@H]2O)[C@H](O)[C@H](O[C@H]2O[C@H](CO)[C@@H](O)[C@H](O[C@@H]3O[C@@H](C)[C@H](O)[C@@H](O)[C@H]3O)[C@H]2O)[C@H]1O

1221.391 g/mol (C₅₉H₉₆O₂₆)

Two new saponins containing five sugars have been isolated from the ethanol extract of the root of Dipsocus japonicus and their structures established as (3-O-α-L-rhamnopyranosyl(1→3)- α-D-glycopyranosyl(1→3)-α-L-rhamnopyranosyl(1→2）-α-L-arabinopyranosyl-hederagenin-28-O-α-D-glycopyranoside(1) and 3-O-α-D-glycopyranosyl(1→4)[α-L-rhamnopyranosyl(1→3)]-α-D-glycopyranosyl(1→3)-α-L-rhamnopyranosyl(1→2)-α-L-arabinopyranosyl-oleanoic acid (2). Two new NMR techniques, 1D-SEMDY and NOE difference spectroscopy in rotating frame have been successfully used to determine the chemical structure of oligosaccharide chains of the saponins. The results obtained showed that the sites of glycosylation and the sequence of sugars in the saponins can be determined unambiguously and total assignment of severely overlapping proton resonance of sugar residues were achieved, without having recourse to chemical degration or modification.

structural determination of oligosaccharide chains, 1D-SEMDY, Dipsocus japonicus, ROE difference spectroscopy

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

C[C@@H]1O[C@@H](O[C@H]2[C@H](O[C@H]3CC[C@@]4(C)[C@@H](CC[C@]5(C)[C@@H]4CC=C4[C@@H]6CC(C)(C)CC[C@]6(C(=O)O)CC[C@]45C)C3(C)C)O[C@@H](C)[C@H](O)[C@H]2O)[C@H](O)[C@H](O[C@H]2O[C@H](CO)[C@@H](O[C@H]3O[C@H](CO)[C@@H](O)[C@H](O)[C@H]3O)[C@H](O[C@@H]3O[C@@H](C)[C@H](O)[C@@H](O)[C@H]3O)[C@H]2O)[C@H]1O

1219.419 g/mol (C₆₀H₉₈O₂₅)