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Two Unusual Methylidenecyclopropane Glucosides from Metaxya rostrata C.Presl.

Kainz KP, Virtbauer J, Kählig H, Arion V, Donath O, Reznicek G, Huber W, Marian B, Krenn L - Helv. Chim. Acta (2012)

Bottom Line: Two new natural compounds, (1R,2E)-2-(6-hydroxyhexylidene)cyclopropyl-β-D-glucopyranoside (1) and (6E)-6-[(2R)-2-(β-D-glucopyranosyloxy)cyclopropylidene]hexanoic acid (2), glucosides of a very rare methylidenecyclopropane alcohol, as well as two known glycosides of phenolic acids, namely 4-O-β-D-glucopyranosylcaffeic acid (3) and (E)-4-O-β-D-glucopyranosylcoumaric acid (4), and methyl α-fructofuranoside (5) were isolated for the first time from the rhizomes of the tree fern Metaxya rostrata C.Presl.The structures were elucidated on the basis of detailed spectroscopic data analysis, and the structure of 1 was additionally confirmed by X-ray crystal-structure analysis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacognosy, University of Vienna Althanstr. 14, AT-1090 Vienna.

ABSTRACT
Two new natural compounds, (1R,2E)-2-(6-hydroxyhexylidene)cyclopropyl-β-D-glucopyranoside (1) and (6E)-6-[(2R)-2-(β-D-glucopyranosyloxy)cyclopropylidene]hexanoic acid (2), glucosides of a very rare methylidenecyclopropane alcohol, as well as two known glycosides of phenolic acids, namely 4-O-β-D-glucopyranosylcaffeic acid (3) and (E)-4-O-β-D-glucopyranosylcoumaric acid (4), and methyl α-fructofuranoside (5) were isolated for the first time from the rhizomes of the tree fern Metaxya rostrata C.Presl. The structures were elucidated on the basis of detailed spectroscopic data analysis, and the structure of 1 was additionally confirmed by X-ray crystal-structure analysis.

No MeSH data available.


HMBCs of compound 2
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fig02: HMBCs of compound 2

Mentions: In the NMR experiments, the sugar part was easily characterized as a β-glucopyranose. The aglycon showed mainly signals for CH2 groups in the aliphatic region, one C = C bond CH signal, and an additional CH signal at 4.18 ppm in the 1H-NMR. The 13C-NMR additionally showed the resonance of a quaternary olefinic Catom at 123.9 ppm. The structure of the aglycon could be identified as a 2-(6- hydroxyhexylidene)cyclopropanol moiety (for the structure, see Fig. 1), linked glycosidically with glucose via the alcohol attached to the cyclopropane ring. This result is based on the characteristic 1H- and 13C-NMR chemical shifts (Table 1) of the cyclopropane signals together with rather large 1H,13C one-bond coupling constants, namely 188.2 Hz for H−C(9’), and 163.9 and 161.0 Hz for the CH2 (8’), respectively [3]. The observed C = C stretching frequency of 1775 cm−1 in the IR spectrum of 1 is in accordance with published data of similar methylidenecyclopropane structures [4]. Numerous HMBCs established all the necessary connectivities, e.g., the interglycosidic linkage by a cross-peak from H − C(1) to C(9’), or correlations within the aglycon from H − C(6’) to the C(9’), C(8’), C(5’), and C(4’), and from H − C(1’) to C(2’) and C(3’), respectively (Fig. 2). NOESY Cross-peaks from CH2(5’) to CH2 (8’) within the cyclopropanol revealed the geometry of the C = C bond. Attached to the C = C bond is a C5 aliphatic chain terminated by an alcohol function. From all data above, the structure of compound 1 was established as (2E)-2-(6-hydroxyhexylidene)cyclopropyl-β- d-glucopyranoside.


Two Unusual Methylidenecyclopropane Glucosides from Metaxya rostrata C.Presl.

Kainz KP, Virtbauer J, Kählig H, Arion V, Donath O, Reznicek G, Huber W, Marian B, Krenn L - Helv. Chim. Acta (2012)

HMBCs of compound 2
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3569612&req=5

fig02: HMBCs of compound 2
Mentions: In the NMR experiments, the sugar part was easily characterized as a β-glucopyranose. The aglycon showed mainly signals for CH2 groups in the aliphatic region, one C = C bond CH signal, and an additional CH signal at 4.18 ppm in the 1H-NMR. The 13C-NMR additionally showed the resonance of a quaternary olefinic Catom at 123.9 ppm. The structure of the aglycon could be identified as a 2-(6- hydroxyhexylidene)cyclopropanol moiety (for the structure, see Fig. 1), linked glycosidically with glucose via the alcohol attached to the cyclopropane ring. This result is based on the characteristic 1H- and 13C-NMR chemical shifts (Table 1) of the cyclopropane signals together with rather large 1H,13C one-bond coupling constants, namely 188.2 Hz for H−C(9’), and 163.9 and 161.0 Hz for the CH2 (8’), respectively [3]. The observed C = C stretching frequency of 1775 cm−1 in the IR spectrum of 1 is in accordance with published data of similar methylidenecyclopropane structures [4]. Numerous HMBCs established all the necessary connectivities, e.g., the interglycosidic linkage by a cross-peak from H − C(1) to C(9’), or correlations within the aglycon from H − C(6’) to the C(9’), C(8’), C(5’), and C(4’), and from H − C(1’) to C(2’) and C(3’), respectively (Fig. 2). NOESY Cross-peaks from CH2(5’) to CH2 (8’) within the cyclopropanol revealed the geometry of the C = C bond. Attached to the C = C bond is a C5 aliphatic chain terminated by an alcohol function. From all data above, the structure of compound 1 was established as (2E)-2-(6-hydroxyhexylidene)cyclopropyl-β- d-glucopyranoside.

Bottom Line: Two new natural compounds, (1R,2E)-2-(6-hydroxyhexylidene)cyclopropyl-β-D-glucopyranoside (1) and (6E)-6-[(2R)-2-(β-D-glucopyranosyloxy)cyclopropylidene]hexanoic acid (2), glucosides of a very rare methylidenecyclopropane alcohol, as well as two known glycosides of phenolic acids, namely 4-O-β-D-glucopyranosylcaffeic acid (3) and (E)-4-O-β-D-glucopyranosylcoumaric acid (4), and methyl α-fructofuranoside (5) were isolated for the first time from the rhizomes of the tree fern Metaxya rostrata C.Presl.The structures were elucidated on the basis of detailed spectroscopic data analysis, and the structure of 1 was additionally confirmed by X-ray crystal-structure analysis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacognosy, University of Vienna Althanstr. 14, AT-1090 Vienna.

ABSTRACT
Two new natural compounds, (1R,2E)-2-(6-hydroxyhexylidene)cyclopropyl-β-D-glucopyranoside (1) and (6E)-6-[(2R)-2-(β-D-glucopyranosyloxy)cyclopropylidene]hexanoic acid (2), glucosides of a very rare methylidenecyclopropane alcohol, as well as two known glycosides of phenolic acids, namely 4-O-β-D-glucopyranosylcaffeic acid (3) and (E)-4-O-β-D-glucopyranosylcoumaric acid (4), and methyl α-fructofuranoside (5) were isolated for the first time from the rhizomes of the tree fern Metaxya rostrata C.Presl. The structures were elucidated on the basis of detailed spectroscopic data analysis, and the structure of 1 was additionally confirmed by X-ray crystal-structure analysis.

No MeSH data available.