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Ypsiyunnosides A – E, Five New Cholestanol Glycosides from Ypsilandra yunnanensis

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ABSTRACT

151: Phytochemical investigation on the whole plants of Ypsilandra yunnanensis was carried out for the first time and led to the isolation of five new cholestanol glycosides, ypsiyunnosides A–E (–), and one known analogue. Their structures were determined mainly by detailed spectroscopic analysis, including extensive 1D and 2D NMR, MS and UV, as well as chemical methods. Among them, compound possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon, which was identified as (23R,25R)-3β,16α,26-triol-16,23-cyclocholest-5,17(20)-dien-22-one. Their induced platelet aggregation activities and cytotoxicities were evaluated.

151: Five new cholestanol glycosides, ypsiyunnosides A–E (–), were isolated from the whole plants of Ypsilandrayunnanensis. Compound possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon. Their structures were elucidated by a combination of 1D and 2D NMR, MS and chemical analysis.

Electronic supplementary material: The online version of this article (doi:10.1007/s13659-016-0098-2) contains supplementary material, which is available to authorized users.

No MeSH data available.


Key ROESY correlations for the aglycone of 1
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Fig4: Key ROESY correlations for the aglycone of 1

Mentions: Comparison of the 1H and 13C NMR spectra of the aglycone of 1 with those of parispseudoside C (6) [10] led to find the absence of one carbonyl group, one methylene and the appearance of an oxygen-bearing quaternary carbon (δC 83.0) and one methine (δH 2.44; δC 57.6) in 1. In addition, one carbonyl group, two double bonds and five monosaccharides in compound 1 accounted for 8 degrees of unsaturation, and the remaining five degrees of unsaturation required that the aglycone of 1 be pentacyclic. Therefore, it was supposed that compound 1 was a 23,16-aldol condensation product of parispseudoside C (6), which was verified by the 1H–1H COSY and HMBC spectra. The 1H–1H COSY correlations (Fig. 2) of δH 4.03 (Ha-26) and 3.72 (Hb-26) with δH 2.51 (H-25), of δH 2.51 (H-25) with δH 2.39 (Ha-24) and 1.98 (Hb-24), of δH 2.51 (H-25) with δH 1.12 (Me-27), and of δH 1.98 (Hb-24) with δH 2.44 (H-23), together with the HMBC correlation (Fig. 2) of δH 2.51 (H-25) with δC 57.6 (C-23) indicated that the methine was assigned to C-23. The observed HMBC correlations (Fig. 2) from Me-21 to C-17, C-20, and C-22, from H-23 to C-16, and C-22, from H2-24 to C-16 and C-22 supported that the formation of a cyclopentane with α,β-unsaturated ketone group by 23,16-aldol condensation (Fig. 3). The ROESY correlations (Fig. 4) of Me-18/H-8, H-8/Hβ-15 (δH 1.98), and Hβ-15/H-23 suggested that H-23 was β-oriented. Furthermore, the obvious correlation from Hβ-15 to H-23 hinted that OH-16 was α-oriented. The 25R-configuration of 1 was deduced from the geminal proton resonances of Ha-26 and Hb-26, which showed Δab (δHa – δHb) of 0.31, less than 0.48 [11].Fig. 2


Ypsiyunnosides A – E, Five New Cholestanol Glycosides from Ypsilandra yunnanensis
Key ROESY correlations for the aglycone of 1
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5385661&req=5

Fig4: Key ROESY correlations for the aglycone of 1
Mentions: Comparison of the 1H and 13C NMR spectra of the aglycone of 1 with those of parispseudoside C (6) [10] led to find the absence of one carbonyl group, one methylene and the appearance of an oxygen-bearing quaternary carbon (δC 83.0) and one methine (δH 2.44; δC 57.6) in 1. In addition, one carbonyl group, two double bonds and five monosaccharides in compound 1 accounted for 8 degrees of unsaturation, and the remaining five degrees of unsaturation required that the aglycone of 1 be pentacyclic. Therefore, it was supposed that compound 1 was a 23,16-aldol condensation product of parispseudoside C (6), which was verified by the 1H–1H COSY and HMBC spectra. The 1H–1H COSY correlations (Fig. 2) of δH 4.03 (Ha-26) and 3.72 (Hb-26) with δH 2.51 (H-25), of δH 2.51 (H-25) with δH 2.39 (Ha-24) and 1.98 (Hb-24), of δH 2.51 (H-25) with δH 1.12 (Me-27), and of δH 1.98 (Hb-24) with δH 2.44 (H-23), together with the HMBC correlation (Fig. 2) of δH 2.51 (H-25) with δC 57.6 (C-23) indicated that the methine was assigned to C-23. The observed HMBC correlations (Fig. 2) from Me-21 to C-17, C-20, and C-22, from H-23 to C-16, and C-22, from H2-24 to C-16 and C-22 supported that the formation of a cyclopentane with α,β-unsaturated ketone group by 23,16-aldol condensation (Fig. 3). The ROESY correlations (Fig. 4) of Me-18/H-8, H-8/Hβ-15 (δH 1.98), and Hβ-15/H-23 suggested that H-23 was β-oriented. Furthermore, the obvious correlation from Hβ-15 to H-23 hinted that OH-16 was α-oriented. The 25R-configuration of 1 was deduced from the geminal proton resonances of Ha-26 and Hb-26, which showed Δab (δHa – δHb) of 0.31, less than 0.48 [11].Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

151: Phytochemical investigation on the whole plants of Ypsilandra yunnanensis was carried out for the first time and led to the isolation of five new cholestanol glycosides, ypsiyunnosides A–E (–), and one known analogue. Their structures were determined mainly by detailed spectroscopic analysis, including extensive 1D and 2D NMR, MS and UV, as well as chemical methods. Among them, compound possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon, which was identified as (23R,25R)-3β,16α,26-triol-16,23-cyclocholest-5,17(20)-dien-22-one. Their induced platelet aggregation activities and cytotoxicities were evaluated.

151: Five new cholestanol glycosides, ypsiyunnosides A–E (–), were isolated from the whole plants of Ypsilandrayunnanensis. Compound possessed a rare 6/6/6/5/5 fused-rings cholestanol sketelon. Their structures were elucidated by a combination of 1D and 2D NMR, MS and chemical analysis.

Electronic supplementary material: The online version of this article (doi:10.1007/s13659-016-0098-2) contains supplementary material, which is available to authorized users.

No MeSH data available.