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Results for “STILBENES”

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PubMed2004

Lakoochins A and B, new antimycobacterial stilbene derivatives from Artocarpus lakoocha.

Two new stilbene derivatives, lakoochins A (1) and B (2), were isolated from the roots of Artocarpus lakoocha. The structures of 1 and 2 were elucidated by analysis of their spectral data. Lakoochins A (1) and B (2) exhibited antimycobacterial activity with the respective MIC values of 12.5 and 50 microg/mL. While 1 was cytotoxic against the BC (breast cancer) cell line (IC(50) 6.1 microg/mL) but inactive (at 20 microg/mL) toward KB (nasopharyngeal carcinoma) cells, compound 2 possessed cytotoxicity against the BC and KB cell lines with IC(50) values of 3.1 and 6.1 microg/mL, respectively.

Anti-Bacterial Agents↗
PubMed2005

Two new hepatoprotective stilbene glycosides from Acer mono leaves.

Two new stilbene glycosides, 5-O-methyl-(E)-resveratrol 3-O-beta-d-glucopyranoside (1) and 5-O-methyl-(E)-resveratrol 3-O-beta-D-apiofuranosyl-(1-->6)-beta-d-glucopyranoside (2), were isolated from the leaves of Acer mono, along with seven known compounds. Among these compounds, 1, 2, and quercetin (3) showed significant hepatoprotective activities against H(2)O(2)-induced toxicity in primary cultures of rat hepatocytes.

Acer↗
PubMed1998

Cytotoxic geranyl stilbenes from Macaranga schweinfurthii.

Three novel geranyl stilbenes, schweinfurthins A, B, and C (1, 2, and 3), were isolated from the Cameroonian plant Macaranga schweinfurthii (Euphorbiaceae) and their structures determined by NMR and mass spectral methods. The cytotoxicity profile of the schweinfurthins tested in the NCI 60-cell screen was similar to that of the stelletins and cephalostatins, suggesting that these structurally diverse natural products may share similar mechanisms of cytotoxicity.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Characterization of a pine multigene family containing elicitor-responsive stilbene synthase genes.

Young pine seedlings respond to environmental stress by induced synthesis of pinosylvin, a stilbene phytoalexin. Heartwood of pine trees is characterized by a high content of pinosylvin. The formation of pinosylvin from cinnamoyl-CoA and three molecules malonyl-CoA catalysed by pinosylvin synthase is typical of the genus Pinus. Its enzyme activity not detectable in unstressed seedlings is substantially increased upon application of stimuli like UV-light or infection with the phytopathogenic fungus Botrytis cinerea. A genomic DNA library was screened with pinosylvin synthase cDNA pSP-54 as a probe. Ten clones were isolated and grouped into five subclasses according to the size of their introns. After subcloning into plasmid T7T3, four different members of the five gene subclasses were characterized by sequencing. Emphasis was put on isolating various promoters and analyzing and comparing their responsiveness. The amino acid sequences deduced from genes PST-1, PST-2, PST-3 and PST-5 shared an overall identity of more than 95%. In gene PST-5, the putative translation start site ATG was replaced by CTG. While promoter regions near the TATAA box were almost identical PST-1, PST-2 and PST-3, further upstream sequences differed substantially. Differences in promoter strength were analysed both in transgenic tobacco plants and by transient expression in tobacco protoplasts. Constructs used contained the bacterial beta-glucuronidase under the control of the promoters of pine genes PST-1, PST-2 and PST-3. Upon treatment with UV light or fungal elicitor, the promoter of PST-1 showed highest responsiveness and led to tissue-specific expression in vascular bundles. The data suggest that in pine the gene product of PST-1 is responsible for both the stress response in seedlings and pinosylvin formation in the heartwood.

Acyltransferases↗
PubMed2005

Unexpected Z-stereoselectivity in the Ramberg-Bäcklund reaction of diarylsulfones leading to cis-stilbenes: the effect of aryl substituents and application in the synthesis of the integrastatin nucleus.

With certain substituent patterns, benzyl benzyl sulfone systems have been found to give unexpectedly high Z-stereoselectivity (up to E:Z = 1:16) in the Meyers variant of the Ramberg-Bäcklund reaction. A range of sulfones, bearing various aryl substituents, were explored to rationalize this unprecedented selectivity for Z-stilbene systems. This high level of double bond stereocontrol has also been utilized in the synthesis of integrastatin nucleus, the core of two highly bioactive anti-HIV compounds.

Alkenes↗
PubMed2005

Novel reaction products from the hypervalent iodine oxidation of hydroxylated stilbenes and isoflavones.

Novel reaction pathways for the hypervalent iodine-mediated oxidation of bioactive phenols containing extended conjugated pi-systems are described. Oxidation of 4-hydroxystilbenes in methanol using a hypervalent iodine-based oxidant led to the formal 1,2-addition of methoxy groups across the central stilbene double bond. Treatment of the structurally related 4-hydroxyisoflavone with di(trifluoroacetoxy)iodobenzene leads to the surprising formation of 2,4'-dihydroxybenzil. Potential mechanisms for these new reaction pathways are discussed, and the X-ray crystal structure of 2,4'-dihydroxybenzil is presented. In contrast, oxidation of the corresponding 3-hydroxystilbenes and 3-hydroxyisoflavone led to conventional dienone oxidation products. The antitumour implications of these oxidation processes are briefly highlighted; the novel 4-substituted phenolic oxidation products were found to be inactive in terms of in vitro antitumour cellular activity, whereas the 3-substituted phenol products gave novel agents with potent and enhanced antitumour activity in the HCT 116 cancer cell line.

Antineoplastic Agents↗
PubMed2004

Synthesis and anti-implantation activity of new stilbene derivatives.

New stilbene (CAS 56-53-1) derivatives have been synthesized by reductive elimination of desoxybenzoin analogs which were obtained by Fries rearrangement of the corresponding phenolic esters. The chemical structures of the compounds obtained were confirmed by 1H-NMR, IR and elemental analysis. Anti-implantation activity of the compounds was determined by performing experiments with adult male and female Spargue-Dawley rats of proven fertility. A 67% inhibition of implantation was observed separately with compounds 3f and 3i.

Animals↗
PubMed2000

Inhibition of tyrosinase by flavonoids, stilbenes and related 4-substituted resorcinols: structure-activity investigations.

Several flavonoids, stilbenes and related 4-substituted resorcinols, obtained from Artocarpus incisus and other plants or synthesized, were tested for their inhibitory activity against tyrosinase. The structure-activity relationships suggested that specific natural or synthesized compounds having the 4-substituted resorcinol skeleton have potent tyrosinase inhibitory ability. Kinetic studies have indicated that specific compounds having the 4-substituted resorcinol skeleton exhibit competitive inhibition of the oxidation of DL-beta-(3,4-dihydroxyphenyl)alanine (DL-DOPA) by mushroom tyrosinase. These findings could lead to the design and discovery of new tyrosinase inhibitors.

Enzyme Inhibitors↗
PubMed2001

Three new stilbene trimers from the lianas of Gnetum hainanense.

Three new stilbene trimers, gnetuhainins M-O (1-3), were isolated from the lianas of Gnetum hainanense. Their structures and relative configurations were determined by spectroscopic evidence, especially on 2D NMR analysis. The anti-inflammatory activity has been tested for the isolated compounds.

Molecular Structure↗
PubMed2001

Identification and determination of oligomeric stilbenes in the roots of Caragana species by capillary electrophoresis.

A method based on capillary electrophoresis with electrochemical detection (CE-ED) was employed for the determination of one alkaloid (hypaphorine) and the four oligomeric stilbenes, pallidol, kobophenol A, miyabenol C and (+)-alpha-viniferin in the roots of Caragana species. The five analytes could be well separated within 12 min in a 40 cm length capillary at a separation voltage of 12 kV in a 100 mmol/L borate buffer (pH 10.0). The response was linear over about 3 orders of magnitude for all investigated analytes with detection limits (S/N = 3) ranging from 0.0385 to 0.111 mg/L. The five constituents presented in Caragana sinica can also be detected in the roots of other Caragana species, but their contents were quite different. It is demonstrated that CE-ED is a useful technique for the investigation of some electroactive constituents in plants.

China↗
PubMed2002

An isorhapontigenin tetramer and a novel stilbene dimer from Gnetum hainanense.

The first isorhapontigenin tetramer, gnetuhainin R (1) and a novel dimeric stilbene, gnetuhainin S (2) were isolated from the lianas of Gnetum hainanense. Their structures were elucidated on the basis of spectroscopic and chemical evidence, especially 2D NMR analysis. The structure of 2 was further supported by X-ray crystallographic analysis. The anti-inflammatory activity of 1 has been tested, and it showed potent activity of histamine receptor antagonism.

Animals↗
PubMed2003

Halophilols A and B, two new stilbenes from Iris halophila.

A new monomeric stilbene, halophilol A (1), and a new tetrastilbene, halophilol B (2), along with three known oligostilbenes were isolated from the seeds of Iris halophila. Their structures were established on the basis of the spectral data. The oligostilbene skeleton is encountered for the first time in the Iridaceae family. Bioactivity tests showed that 1 had moderate cytotoxicity against KB and HMEC cell lines (IC50 = 17.28 microM, 22.47 microM respectively), while 2 was inactive.

Antineoplastic Agents, Phytogenic↗
PubMed2003

Cyclized geranyl stilbenes from the rhizomes of Helminthostachys zeylanica.

Three new cyclized geranyl stilbenes, ugonstilbene A ( 1), ugonstilbene B ( 2), and ugonstilbene C ( 3), and one known compound 3-hydroxyacetophenone, were isolated from the dried rhizomes of H. zeylanica. The structures of these three new compounds were elucidated on the basis of spectral analysis. Compounds 1 - 3 exhibited moderate antioxidant activity by the DPPH assay with IC (20) of 11.31 +/- 1.11, 38.72 +/- 0.47, and 30.80 +/- 1.19 microM, respectively, while the IC (20) of Trolox was 8.70 +/- 0.95 microM.

Antioxidants↗
PubMed2004

Antiallergic phenanthrenes and stilbenes from the tubers of Gymnadenia conopsea.

The methanolic extract from the tubers of Gymnadenia conopsea showed an antiallergic effect on ear passive cutaneous anaphylaxis reactions in mice. From the methanolic extract, three new dihydrophenanthrenes, gymconopins A ( 1), B ( 2), and C ( 3), and a new dihydrostilbene, gymconopin D ( 4), were isolated together with 10 known phenanthrene and stilbene constituents. The structures of the new compounds were determined on the basis of physicochemical evidence. Next, the inhibitory effects of the principal constituents on the release of beta-hexosaminidase, as a marker of degranulation, in RBL-2H3 cells were examined and five phenanthrenes, gymconopin B ( 2), 4-methoxy-9,10-dihydrophenanthrene-2,7-diol ( 6), 1-(4-hydroxybenzyl)-4-methoxyphenanthrene-2,7-diol ( 7), 1-(4-hydroxybenzyl)-4-methoxy-9,10-dihydrophenanthrene-2,7-diol ( 8), and blestriarene A ( 9), and six dihydrostilbenes, gymconopin D ( 4), batatacin III ( 10), 3'- O-methylbatatacin III ( 11), 3,3'-dihydroxy-2-(4-hydroxybenzyl)-5-methoxybibenzyl ( 12), 3',5-dihydroxy-2-(4-hydroxybenzyl)-3-methoxybibenzyl ( 13), and 3,3'-dihydroxy-2,6-bis(4-hydroxybenzyl)-5-methoxybibenzyl ( 14) were found to inhibit the antigen-induced degranulation by 65.5 to 99.4 % at 100 microM in RBL-2H3 cells.

Animals↗
PubMed2005

Anti-HIV bioactive stilbene dimers of Caragana rosea.

Bioassay-guided fractionation of the ethanol extract of the aerial parts of Caragana rosea Turcz. led to the isolation of two new (cararosinol C and cararosinol D) and four known [scirpusin A (1), cis-scirpusin A (2), maackin (3), scirpusin B (4)] stilbene dimers. This is the first identification of these compounds from this plant and the first time that compound 2 has been isolated as a natural compound. Their structures were established mainly by spectral means. An in vitro assay against HIV-1 (IIIB), demonstrated compounds 1 and 4 to be active against HIV, with EC50 values of 10 microg/mL and 7 microg/mL respectively.

Anti-HIV Agents↗
PubMed2005

Two new antioxidant stilbene dimers, parthenostilbenins A and B from Parthenocissus tricuspidata.

The ethyl acetate fraction of an aqueous alcoholic extract from the stem of Parthenocissus tricuspidata yielded 11 known compounds (1-11) and two new stilbene dimers parthenostilbenins A (12) and B (13) upon purification either by preparative TLC or reversed phase HPLC. The structures of the new isolates were identified using a combination of FAB-MS and NMR. These compounds were assessed for antioxidant activities in three different bioassay systems. Among them, piceatannol showed the strongest inhibitory activity in these assay systems. Two new compounds, parthenostilbenins A (12) and B (13) inhibited lipid peroxidation (IC (50) = 20.35 +/- 1.22 and 18.68 +/- 0.51 microg/mL, respectively) in a rat liver homogenate.

Animals↗