Search results for "stereochemistry"

ChemInform Abstract: Non-Steroidal Antiinflammatory Agents. Part 22. Pyrrolidino-enaminones with an Acetic Acid Function at C-3: Synthesis and Inhibi…

2010

Foetidissimosides C—F, Novel Glycosides from the Roots of Cucurbita foetidissima.

2004

Two novel echinocystic acid (=(3β,16α)-3,16-dihydroxyolean-12-en-28-oic acid) glycosides, foetidissimosides C (1), and D (2), along with new cucurbitane glycosides, i.e., foetidissimosides E/F (3/4) as an 1 : 1 mixture of the (24R)/(24S) epimers, were obtained from the roots of Cucurbita foetidissima. Their structures were elucidated by means of a combination of homo- and heteronuclear 2D-NMR techniques (COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC), and by FAB-MS. The new compounds were characterized as (3β,16α)-28-{[O-β-D-glucopyranosyl-(13)-O-β-D-xylopyranosyl-(14)-O-6-deoxy-α-L-mannopyranosyl-(12)-α-L-arabinopyranosyl]oxy}-16-hydroxy-28-oxoolean -12-en-3-yl β-D-glucopyranosiduronic acid (1…

Metabolism of stilbene phytoalexins by Botrytis cinerea: 1. Characterization of a resveratrol dehydrodimer

1998

Abstract Resveratrol, a grapevine phytoalexin, is metabolized by a laccase-like stilbene-oxidase of Botrytis cinerea, the causal organism for grey mould. Characterization of one major metabolite formed during this degradation process as a resveratrol dehydrodimer allowed us to precize the reaction mechanism of this enzyme on stilbenes.

New sesquiterpene lactones and acetylenes from chrysanthemum lavandulifolium

1990

Abstract The aerial parts of Chrysanthemum lavandulifolium Mak. (Asteraceae) yielded three new acetylenes of the spiroacetal type 1-3, as well as two new germacranolides 4-5 and several known lactones.

Rollimembrin, a novel acetogenin inhibitor of mammalian mitochondrial complex I

1997

Abstract Rollimembrin (3), is a new adjacent bis-tetrahydrofuranic acetogenin with a scarce relative configuration, threo/cis/threo/cis/erythro, isolated from Rollinia membranacea seeds. The mechanism of cytotoxic activity, determined by NADH-oxidase experiments, establish that rollimembrin (3) is the most potent inhibitor of mammalian mitochondrial complex I.

New Acylated Saponins fromPolygala myrtifolia

2003

The ten new acylated presenegenin (=(2β,3β,4α)-2,3,27-trihydroxyolean-12-ene-23,28-dioic acid) glycosides 1–10 have been isolated by successive MPLC from the roots of Polygala myrtifolia L. as five inseparable mixtures of the trans- and cis-4-methoxycinnamoyl derivatives, i.e., myrtifoliosides A1/A2 (1/2), B1/B2 (3/4), C1/C2 (5/6), D1/D2 (7/8), and E1/E2 (9/10). Their structures were elucidated mainly by extensive spectroscopic experiments, including 2D NMR techniques, as 3-O-(β-D-glucopyranosyl)presenegenin 28-{O-β-D-galactopyranosyl-(13)-O-β-D-xylopyranosyl-(14)-O-[D-apio-β-D-furanosyl-(13)]-O-α-L-rhamnopyranosyl-(12)-O-[α-L-arabinopyranosyl-(13)]-4-O-(trans-4-methoxycinnamoyl)-β-D-fucopy…

New Triterpenoidal Saponins fromGypsophila repens

2007

Six new triterpene glycosides, repensosides A–F (1–6, resp.), were isolated from the roots of Gypsophila repens L. Their structures, established by extensive 1D- and 2D-NMR spectroscopic experiments as well as MS analyses, were found to be based on gypsogenic acid (or gypsogenin) as aglycone, with three to nine branched or unbranched sugar moieties.

Synthetic studies on neoclerodane diterpenes from Salvia splendens: oxidative modifications of ring A.

2011

Salvinorin A (1), a neoclerodane diterpene from the hallucinogenic mint Salvia divinorum, is the only known naturally occurring non-nitrogenous and specific κ-opioid agonist. Some oxidative modifications of the A ring in the congeners of 1 isolated from Salvia splendens salviarin, splenolide B, splendidin and in the non-natural 8-epi-salviarin gave new derivatives, some of which were tested as agonists at opioid receptors. However, none of these compounds were active. The presence of the C-18, C-19 lactone could be at the origin of the observed lack of binding affinity.

Triterpene Saponins from Four Species of the Polygalaceae Family

2005

Twelve triterpene saponins were isolated by successive MPLC over silica gel from four species of Polygalaceae: From Polygala ruwenzoriensis, five new saponins 1–5 of which 1–4 as two pairs of (E)/(Z)-isomers, together with the four known compounds tenuifoline, (E)- and (Z)-senegasaponin b, (E)- and (Z)-senegin II, and polygalasaponin XXVIII, from the genus Carpolobia, one new saponin 6 from C. alba and the known arilloside (11) from C. lutea, and another new triterpene glycoside 7 from Polygala arenaria. Their structures were established mainly by 600-MHz 2D-NMR techniques (1H,1H-COSY, TOCSY, NOESY, HSQC, HMBC) as 3-O-(β-D-glucopyranosyl)presenegenin 28-{O-α-L-arabinopyranosyl-(1  4)-O-β-D-…

New Acylated Triterpene Saponins fromPolygala arenaria

2003

Eight new acylated triterpene saponins 1–8 were isolated from the roots of Polygala arenaria as four inseparable (E)/(Z) mixtures of the 4-methoxycinnamoyl and 3,4-dimethoxycinnamoyl derivatives by repeated MPLC over silica gel. Their structures were established mainly by 600-MHz 2D-NMR techniques (1H,1H-COSY, TOCSY, NOESY, HSQC, HMBC) as 3-O-(β-D-glucopyranosyl)presenegenin 28-(O-β-D-galactopyranosyl-(14)-O-[β-D-glucopyranosyl-(13)]-O-β-D-xylopyranosyl-(14)-O-α-L-rhamnopyranosyl-(12)-{4-O-[(E)-4-methoxycinnamoyl]}-β-D-fucopyranosyl) ester and its (Z)-isomer (1/2), 3-O-(β-D-glucopyranosyl)presenegenin 28-(O-β-D-galactopyranosyl-(14)-O-[β-D-glucopyranosyl-(13)]-O-β-D-xylopyranosyl-(14)-O-α-L…