Ring expansions of crombeone, a natural 5-hydroxypeltogynone

Brandt, E. Vincent; Ferreira, Denise Helena Lombardo; Roux, D. G.

doi:10.1039/c29710000116

Cited by 13 publications

(5 citation statements)

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“…After the emergence of phenolic material 15-ml fractions were collected. (5.4), 498 (32), 456 (62), 414 (34), 397 (37), 372 (47), 355 (25), 344 (14), 330 (28), 313 (15), 302 (15), 297 (43,282 (13), 239 (31), 213 (25), 198 (25), 181 (14), 168 (47), 165 (23), 153 (24), 150 (33), and 139 (100); m/z (f.d.) 649 (loo/,), 572 (loo), and 559 (74); m/z (f.a.b.)…”

Section: Isolation Of Phenolic Metabolites From Willowmentioning

confidence: 99%

[2′,2′]-(+)-Catechin-(+)-taxifolin from commercial willow bark: structure, bonding positions and oxidative cleavage

Kolodziej¹

1988

J. Chem. Soc., Perkin Trans. 1

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~~[2',2'] -( +)-Catechin-( + ) -taxifohn, a novel biflavonoid from commercial willow bark (Salix spp.), is characterized by spectrometric methods. The bonding positions are established by nuclear Overhauser effect difference spectroscopy of the methyl ether acetates of the bi-( +)-taxifolin analogues, which represent products of oxidation of the methylene function of the (+)-catechin moiety and which undergo methylene insertion reactions with diazomethane. Photoinduced oxidative cleavage of the biphenyl-type interflavonoid linkage involving singlet oxygen, accompanied by intermolecular transfer of an acetyl group of the peracetate, yielding a range of flavan-3-01s and dihydroflavonols, provides the first example of this type of biflavonoid photofragmentation.Apart from biflavanoids of black ' and green tea possessing an interflavanoid linkage between the two B-rings of flavan units this type of natural C-C bonding is atypical, the biphenyl moiety being commonly found only in biflavonoids3 and hydrolysable tannins4 The range of natural biflavonoids is now extended by the isolation of novel B-ring, B-ring coupled analogues from commercial willow bark (Salix spp.). Reinvestigation of the ethyl acetate-soluble portion of the bark extract, comprising a mixture of flavonoids, condensed tannins, and phenolic glyco~ides,'-~ revealed a novel biflavonoid as second representative ' O of a flavano-flavonol biflavonoid, but the first in which the monomeric units are linked through a carbon-carbon bond at the B-rings.Evidence for the first natural biflavonoid (1) with different monomeric constituent units (flavan and dihydroflavonol moieties, respectively) coupled uia B-ringS, reported in a preliminary communication,' ' was obtained by acetylation of the appropriate fraction from chromatography on Sephadex LH-20. The free phenol was accompanied by several flavonoids and (+)-catechin (9, the latter serving as precursor of associated condensed tannins. Isolation of the acetate (2) led to its characterization as a derivative of a [2',2']-( + )-catechin-( + )-taxifoh biflavonoid.Analysis of the 300 MHz 'H n.m.r. spectrum of the acetate derivative (2) revealed meta-coupled doublets (A-ring) at 6 6.66 and 6.60 (J 2.2 Hz) in addition to the characteristic ABXY

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Section: Isolation Of Phenolic Metabolites From Willowmentioning

confidence: 99%

[2′,2′]-(+)-Catechin-(+)-taxifolin from commercial willow bark: structure, bonding positions and oxidative cleavage

Kolodziej¹

1988

J. Chem. Soc., Perkin Trans. 1

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“…Moreover, its specific optical rotation ([α] D 25 + 290.9 c 0. 13, CHCl 3 ) was similar to those reported for similar peltogynone derivatives [27]. The structure of 6 was, therefore, determined as (6aR,12aR)-8,10-dihydroxy-9-methoxy-6a,12a-dihydro-5H-isochromeno[4,3-b]chromen-7-one.…”

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confidence: 96%

HPLC-Based Activity Profiling for hERG Channel Inhibitors in the South African Medicinal Plant Galenia africana

Mieri

Saxena

et al. 2015

Planta Med

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The human ether-a-go-go-related gene channel is a voltage-activated K(+) channel involved in cardiac action potential. Its inhibition can lead to QT prolongation, and eventually to potentially fatal arrhythmia. Therefore, it is considered a primary antitarget in safety pharmacology. To assess the risk of human ether-a-go-go-related gene channel inhibition by medicinal plants, 700 extracts from different parts of 142 medicinal plants collected in Southern Africa were screened on Xenopus laevis oocytes. A CH2Cl2 extract from the stems and leaves of Galenia africana (Aizoaceae) reduced the peak tail human ether-a-go-go-related gene current by 50.4 ± 5.5 % (n = 3) at a concentration of 100 µg/mL. By means of high-performance liquid chromatography-based activity profiling, nine flavonoids were identified in the active time windows. However, the human ether-a-go-go-related gene channel inhibition of isolated compounds was less pronounced than that of extract and active microfractions (human ether-a-go-go-related gene inhibition between 10.1 ± 5 and 14.1 ± 1.6 at 100 µM). The two major constituents, 7,8-methylenedioxyflavone (1) and 7,8-dimethoxyflavone (13), were quantified (4.3 % and 9.4 %, respectively, in the extract). Further human ether-a-go-go-related gene inhibition tests for compounds 1 and 13 at 300 µM showed a concentration-dependent inhibitory activity (33.2 ± 12.4 and 30.0 ± 7.4, respectively). In a detailed phytochemical profiling of the active extract, a total of 20 phenolic compounds, including six new natural products, were isolated and identified.

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“…Im Zusammenhang mit Struktur-Wirkungsuntersuchungen haben wir die Eignung des Tetrahydro-3-pyranons (2) -darstellbar aus dem leicht zugänglichen 2 3-Dihy dropyran 6) zur Synthese von Pyrano [3,[2][3][4][5][6] Dem Fonds der Chemischen Industrie danken wir für die finanzielle Unterstützung unserer Arbeit.…”

unclassified

Tetrahydro‐3‐pyranon als Baustein zur Pyrano[3,2‐b]pyran‐Synthese

Eiden¹,

Wanner²

1984

Archiv der Pharmazie

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Das aus dem Pyranon 2 gewonnene Enamin4 setzt sich mit Diketen (6) zumPyrano[3,2-&]pyranon 7 um. Mit 1 ^Dimethylbarbitursäure (10) entsteht das Pyranyliden-Derivat 11. Reaktion von 7 bzw. 11 mit Ammoniak oder primären Aminen fuhrt zu den Pyrano-pyridin-Derivaten 8,9,12a und 12b. Synthesis of Pymo[3^ft]pyraa from Tetrafaydro^pytaiKmc *The enamine 4, obtained from the pyranone 2, reacts with diketene (6) to yield the pyrano[3,2-fr]pyranone 7. Reaction with 13-dimethylbarbituric acid (10) results in the formation of the pyranyiidene derivative 11. Reaction of 7 or U with ammonia or primary amines leads to the formation of the pynmopyridine derivatives 8,9» 12a and 12b.

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Ring expansions of crombeone, a natural 5-hydroxypeltogynone

Cited by 13 publications

References 0 publications

[2′,2′]-(+)-Catechin-(+)-taxifolin from commercial willow bark: structure, bonding positions and oxidative cleavage

[2′,2′]-(+)-Catechin-(+)-taxifolin from commercial willow bark: structure, bonding positions and oxidative cleavage

HPLC-Based Activity Profiling for hERG Channel Inhibitors in the South African Medicinal Plant Galenia africana

Tetrahydro‐3‐pyranon als Baustein zur Pyrano[3,2‐b]pyran‐Synthese

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