Displaying publications 1 - 20 of 22 in total

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  1. Hong FJ, Low YY, Chong KW, Thomas NF, Kam TS
    J Org Chem, 2014 May 16;79(10):4528-43.
    PMID: 24754525 DOI: 10.1021/jo500559r
    A systematic study of the electrochemical oxidation of 1,2-diarylalkenes was carried out with the focus on detailed product studies and variation of product type as a function of aromatic substitution. A reinvestigation of the electrochemical oxidation of 4,4'-dimethoxystilbene under various conditions was first carried out, and all products formed were fully characterized and quantitated. This was followed by a systematic investigation of the effect of aromatic substitution on the nature and distribution of the products. The aromatic substituents were found to fall into three main categories, viz., substrates in which the nature and position of the aromatic substituents gave rise to essentially the same products as 4,4'-dimethoxystilbene, for example, tetraaryltetrahydrofurans, dehydrotetralins, and aldehydes (p-MeO or p-NMe2 on one ring and X on the other ring, where X = o-MeO or p-alkyl, or m- or p-EWG; e.g., 4-methoxy-4'-trifluoromethylstilbene); those that gave rise to a mixture of indanyl (or tetralinyl) acetamides and dehydrotetralins (or pallidols) (both or one ring substituted by alkyl groups, e.g., 4,4'-dimethylstilbene); and those where strategic placement of donor groups, such as OMe and OH, led to the formation of ampelopsin F and pallidol-type carbon skeletons (e.g., 4,3',4'-trimethoxystilbene). Reaction pathways to rationalize the formation of the different products are presented.
    Matched MeSH terms: Stilbenes/chemistry*
  2. Velu SS, Di Meo F, Trouillas P, Sancho-Garcia JC, Weber JF
    J Nat Prod, 2013 Apr 26;76(4):538-46.
    PMID: 23441649 DOI: 10.1021/np300705p
    Oligostilbenoids (e.g., ampelopsin F, viniferin, pallidol) result from homogeneous or heterogeneous coupling of monomeric stilbenoid units, leading to various chemical structures. Oligostilbenoid synthesis is regio- and stereocontrolled. To tackle this regio- and stereocontrol, a supramolecular chemistry approach is required that can be achieved by quantum chemistry. The stability of noncovalent π-stacks, formed between two stilbenoid units prior to oxidation, is accurately evaluated with density functional theory (DFT) including dispersive effects (within the DFT-D formalism). These noncovalent arrangements drive the regiocontrol. The rest of the chemical pathway is a succession of dearomatization and rearomatization stages. The thermodynamics and kinetics of the processes are calculated with classical hybrid functionals. This study allows discrimination between the two main possible chemical pathways, namely, radical-neutral and radical-radical reactions. The former appears more likely, thermodynamics and kinetics being in perfect agreement with the experimental 1:2 ratio obtained for ampelopsin F:pallidol analogues, respectively.
    Matched MeSH terms: Stilbenes/chemistry*
  3. Azmi MN, Din MF, Kee CH, Suhaimi M, Ping AK, Ahmad K, et al.
    Int J Mol Sci, 2013;14(12):23369-89.
    PMID: 24287912 DOI: 10.3390/ijms141223369
    Resveratrol, a natural stilbene found in grapes and wines exhibits a wide range of pharmacological properties. Resveratrol is also known as a good chemopreventive agent for inhibiting carcinogenesis processes that target kinases, cyclooxygenases, ribonucleotide reductase and DNA polymerases. A total of 19 analogues with an amide moiety were synthesized and the cytotoxic effects of the analogues on a series of human cancer cell lines are reported. Three compounds 6d, 6i and 6n showed potent cytotoxicity against prostate cancer DU-145 (IC50=16.68 µM), colon cancer HT-29 (IC50=7.51 µM) and breast cancer MCF-7 (IC50=21.24 µM), respectively, which are comparable with vinblastine. The resveratrol analogues were synthesized using the Heck method.
    Matched MeSH terms: Stilbenes/chemistry*
  4. Zawawi NK, Ahmat N, Mazatulikhma MZ, Shafiq RM, Wahid NH, Sufian AS
    Nat Prod Res, 2013;27(17):1589-93.
    PMID: 23035830 DOI: 10.1080/14786419.2012.730047
    Phytochemical investigation on the stem bark of Shorea maxwelliana yielded five oligostilbenoids identified as α-viniferin (1), maximol A (2), vaticanol A (3), suffruticosol A (4) and vaticanol G (5). Chemotaxonomy of isolated compounds was discussed briefly. Major compounds were tested for neurotoxic and cytotoxic activities. Neurotoxicity for all tested compounds did not pose any toxic effect against cultured cell (cell viability range ±100-94%). Compounds 2-5 possessed active cyctotoxic activity against HL60 cell line with IC50 values range of 2.7-78 µg mL(-1).
    Matched MeSH terms: Stilbenes/chemistry*
  5. Wibowo A, Ahmat N, Hamzah AS, Low AL, Mohamad SA, Khong HY, et al.
    Fitoterapia, 2012 Dec;83(8):1569-75.
    PMID: 22982329 DOI: 10.1016/j.fitote.2012.09.004
    A new oligostilbenoid tetramer, malaysianol B (1), was isolated from the acetone extract of the stem bark of Dryobalanops lanceolata along with seven oligostilbenoids tetramers; hopeaphenol (2), stenophyllol A (3), nepalensinol B (4), vaticanol B (5) and C (6), upunaphenol D (7), and flexuosol A (8). The structures of the isolated compounds were established on the basis of their spectroscopic data evidence. The antibacterial activity of the isolated compounds was evaluated using resazurin microtitre-plate assay.
    Matched MeSH terms: Stilbenes/chemistry*
  6. Kee CH, Ariffin A, Awang K, Noorbatcha I, Takeya K, Morita H, et al.
    Molecules, 2011 Aug 25;16(9):7267-87.
    PMID: 21869754 DOI: 10.3390/molecules16097267
    The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramido- stilbene undergoes FeCl(3) promoted cyclization to produce only indoline, while n-butyramidostilbene, under the same conditions, produces both indoline and bisindoline.
    Matched MeSH terms: Stilbenes/chemistry*
  7. Wibowo A, Ahmat N, Hamzah AS, Sufian AS, Ismail NH, Ahmad R, et al.
    Fitoterapia, 2011 Jun;82(4):676-81.
    PMID: 21338657 DOI: 10.1016/j.fitote.2011.02.006
    A new resveratrol trimer, malaysianol A (1), five known resveratrol oligomers: laevifonol (2), ampelopsin E (3), α-viniferin (4), ε-viniferin (5), diptoindonesin A (6), and bergenin (7) have been isolated from the acetone extract of the stem bark of Dryobalanops aromatica by combination of vacuum and radial chromatography techniques. Their structures were established on the basis of their spectroscopic evidence and comparison with the published data. The cytotoxic activity of the compounds was tested against several cell lines in which compound 4 was found to inhibit strongly the growth of HL-60 cell line.
    Matched MeSH terms: Stilbenes/chemistry
  8. Velu SS, Buniyamin I, Ching LK, Feroz F, Noorbatcha I, Gee LC, et al.
    Chemistry, 2008;14(36):11376-84.
    PMID: 19003831 DOI: 10.1002/chem.200801575
    Oligostilbenoids are polyphenols that are widely distributed in nature with multifaceted biological activities. To achieve biomimetic synthesis of unnatural derivatives, we subjected three resveratrol analogues to oligomerization by means of one-electron oxidants. Upon varying the metal oxidant (AgOAc, CuBr(2), FeCl(3)6 H(2)O, FeCl(3)6 H(2)O/NaI, PbO(2), VOF(3)), the solvent (over the whole range of polarities), and the oxygenated substitution pattern of the starting material, stilbenoid oligomers with totally different carbon skeletons were obtained. Here we propose to explain the determinism of the type of skeleton produced with the aid of hard and soft acid/base concepts in conjunction with the solvating properties of the solvents and the preferred alignment by the effect of pi stacking.
    Matched MeSH terms: Stilbenes/chemistry
  9. Seyed MA, Jantan I, Bukhari SN, Vijayaraghavan K
    J Agric Food Chem, 2016 Feb 3;64(4):725-37.
    PMID: 26758628 DOI: 10.1021/acs.jafc.5b05993
    Cancer is a diverse class of diseases characterized by uncontrolled cell growth that constitutes the greatest cause of mortality and morbidity worldwide. Despite steady progress, the treatment modalities of cancer are still insufficient. Several new concepts have emerged for therapeutic intervention in malignant diseases with the goal of identifying specific targets and overcoming resistance against current cytotoxic therapies. Many studies have reported the remarkable and significant properties of dietary plant polyphenols such as curcumin, resveratrol, flavopiridol, indirubin, magnolol, piceatannol, parthenolide, epigallocatechin gallate, and cucurbitacin as anticancer agents known for their pleiotropic effects on cancer, immune cells, and inflammation. Piceatannol, an analogue and metabolite of resveratrol, is a natural stilbene commonly found in grape skins and wine. Compared to resveratrol, this molecule exhibits superior bioactivities as an inhibitor of COX-1/2 and the CSN-associated kinase. Piceatannol is thought to be a potent natural compound with many therapeutic effects, such as the prevention of hypercholesterolemia, arrhythmia, atherosclerosis, angiogenesis, and cardiovascular diseases. It also demonstrates vasorelaxation, antioxidant, and anticancer activities. This comprehensive review summarizes the current data regarding the mechanisms of action of piceatannol, its chemopreventive properties, and its possible therapeutic potential against various types of human cancer.
    Matched MeSH terms: Stilbenes/chemistry
  10. Abe N, Ito T, Ohguchi K, Nasu M, Masuda Y, Oyama M, et al.
    J Nat Prod, 2010 Sep 24;73(9):1499-506.
    PMID: 20735051 DOI: 10.1021/np1002675
    Five new stilbenoids, vatalbinosides A-E (1-5), and 13 known compounds (6-18) were isolated from the stem of Vatica albiramis. The effects of these new compounds on interleukin-1β-induced production of matrix metalloproteinase-1 (MMP-1) in human dermal fibroblasts were examined. Three resveratrol tetramers, (-)-hopeaphenol (6), vaticanol C (13), and stenophyllol C (14), were identified as strong inhibitors of MMP-1 production.
    Matched MeSH terms: Stilbenes/chemistry*
  11. Hasiah AH, Ghazali AR, Weber JF, Velu S, Thomas NF, Inayat Hussain SH
    Hum Exp Toxicol, 2011 Feb;30(2):138-44.
    PMID: 20385705 DOI: 10.1177/0960327110368739
    Stilbenes possess a variety of biological activities including chemopreventive activity. This study was conducted to evaluate the structural activity relationships of six methoxylated stilbene analogues with respect to their cytotoxic effects and antioxidant activities on HepG2 hepatoma and Chang liver cells. The cytotoxic and total antioxidant activities of six stilbene analogues were determined by MTT and Ferric Reducing Antioxidant Power (FRAP) assays, respectively. We found that the cis-methoxylated stilbene: (Z)-3,4,4'-trimethoxystilbene was the most potent and selective antiproliferative agent (IC₅₀ 89 µM) in HepG2 cells. For the total antioxidant activity, compounds possessing hydroxyl groups at the 4' position namely (E)-3-methoxy-4'-hydroxystilbene, (E)-3,5-dimethoxy-4'-hydroxystilbene (pterostilbene), (E)-4-methoxy-4'-hydroxystilbene showed the highest antioxidant activity. Structure activity relationship studies of these compounds demonstrated that the cytotoxic effect and antioxidant activities of the tested compounds in this study were structurally dependent.
    Matched MeSH terms: Stilbenes/chemistry
  12. Zgoda-Pols JR, Freyer AJ, Killmer LB, Porter JR
    J Nat Prod, 2002 Nov;65(11):1554-9.
    PMID: 12444676
    Two new resveratrol tetramers, hopeaphenol A (1) and isohopeaphenol A (2), along with the known vaticaphenol A (3), were isolated from the stem bark of Vatica oblongifolia ssp. oblongifolia through bioassay-guided fractionation. The structures and their relative stereochemistry were determined by spectroscopic techniques. Compounds 1 and 3 demonstrated moderate activity against methicillin-resistant Staphylococcus aureus and Mycobacterium smegmatis.
    Matched MeSH terms: Stilbenes/chemistry
  13. Lee WX, Basri DF, Ghazali AR
    Molecules, 2017 Mar 17;22(3).
    PMID: 28304328 DOI: 10.3390/molecules22030463
    The antibacterial activity of pterostilbene in combination with gentamicin against six strains of Gram-positive and Gram-negative bacteria were investigated. The minimum inhibitory concentration and minimum bactericidal concentration of pterostilbene were determined using microdilution technique whereas the synergistic antibacterial activities of pterostilbene in combination with gentamicin were assessed using checkerboard assay and time-kill kinetic study. Results of the present study showed that the combination effects of pterostilbene with gentamicin were synergistic (FIC index < 0.5) against three susceptible bacteria strains: Staphylococcus aureus ATCC 25923, Escherichia coli O157 and Pseudomonas aeruginosa 15442. However, the time-kill study showed that the interaction was indifference which did not significantly differ from the gentamicin treatment. Furthermore, time-kill study showed that the growth of the tested bacteria was completely attenuated with 2 to 8 h treatment with 0.5 × MIC of pterostilbene and gentamicin. The identified combinations could be of effective therapeutic value against bacterial infections. These findings have potential implications in delaying the development of bacterial resistance as the antibacterial effect was achieved with the lower concentrations of antibacterial agents.
    Matched MeSH terms: Stilbenes/chemistry
  14. Loh YC, Chan SY, Oo CW, Yam MF
    Life Sci, 2021 Aug 01;278:119560.
    PMID: 33915131 DOI: 10.1016/j.lfs.2021.119560
    AIMS: The structure-vasorelaxant activity relationships (SARs) assessment in previous study has found that trans-3,4,4'-trihydroxystilbene (344OH) could potentially act as a vasorelaxing agent with demonstration of over 2-fold maximal relaxation (Rmax) compared to its analogue, resveratrol. The present study focuses on the mechanism of actions and pathways employed by 344OH and compared to its analogue to further speculate the SAR of stilbenoids towards vasorelaxation.

    MATERIALS AND METHODS: The 344OH employed in present study was synthesized based on the protocol in previous study. The vascular responses towards the cumulative addition of 344OH were evaluated using in vitro rat aortic rings assays.

    KEY FINDINGS: The pEC50 and Rmax values were found to be 4.33 ± 0.05 and 106 ± 3.99%, respectively. Results showed that the vasorelaxation of 344OH were predominated by G-protein-coupled muscarinic- (M3) and β2-adrenergic receptors, followed by PGI2/AC/cAMP- and NO/sGC/cGMP-dependent pathways. It was also identified that 344OH employed voltage-activated- (Kv), calcium-activated- (Kca) and inwardly-rectifying (Kir) potassium channels and act as an antagonist for both VOCC and IP3R while regulating the action potential in the vasculature.

    SIGNIFICANCE: The different position of hydroxyl substituent located in A-ring of the stilbenoid backbone in 344OH compared to resveratrol resulted in a significant difference in mechanistic actions that lead to 344OH's fast-acting and less time-dependent vasorelaxation behaviour. This has substantially increased the potential of 344OH to be developed as an effective antihypertensive drug in future. Present findings further strengthen our inferences where the SARs study approach should be carried out as the mainstream methodology in future drug development research.

    Matched MeSH terms: Stilbenes/chemistry
  15. Ahmat N, Wibowo A, Mohamad SA, Low AL, Sufian AS, Yusof MI, et al.
    J Asian Nat Prod Res, 2014;16(11):1099-107.
    PMID: 25034352 DOI: 10.1080/10286020.2014.938059
    A new tetramer oligostilbenoid possessing tetrahydrofuran ring, malaysianol C (1), was isolated from the acetone extract of the stem bark of Dryobalanops lanceolata, together with four known oligostilbenoids nepalensinol E (2), ϵ-viniferin (3), laevifonol (4), and ampelopsin F (5). The structures of isolated compounds were elucidated on the basis of spectral evidence. The antibacterial activity of the isolated compounds was evaluated using resazurin microtitre-plate assay, whereas the cytotoxic activity was tested using MTT assay. The plausible biogenetic routes of the isolated compounds are also discussed.
    Matched MeSH terms: Stilbenes/chemistry
  16. Muhammad A, Sirat HM
    Nat Prod Commun, 2013 Oct;8(10):1435-7.
    PMID: 24354195
    The stem bark extracts of Bauhinia rufescens Lam. (Fabaceae) yielded 6-methoxy-7-methyl-8-hydroxydibenz[b,f]oxepin, alpha-amyrin acetate, beta-sitosterol 3-O-beta-D-xylopyranoside, 4-(2'-Hydroxyphenethyl)-5-methoxy-2-methylphenol, menisdaurin and sequoyitol. Their structures were determined using spectroscopic methods and comparisons with the literature data. For the antimicrobial assay Gram-positive and Gram-negative bacterial and fungal strains were tested, while the tyrosinase inhibition assay utilized L-DOPA as a substrate for the tyrosinase enzyme. 6-Methoxy-7-methyl-8-hydroxydibenz[b,f]oxepin, a-amyrin acetate, beta-sitosterol 3-O-D-xylopyranoside, menisdaurin and sequoyitol showed weak to moderate activities with minimum inhibition concentration (MIC) values in the range of 112.5-900 microg/mL against all bacterial strains, while the MIC values for the fungal strains were in the range of 28.1-450 microg/mL. In the tyrosinase inhibition assay, a-amyrin acetate was found to be moderately active against tyrosinase with an inhibition of 62% at 0.1 mg/mL. This activity was lower than that of the positive control, kojic acid (85%).
    Matched MeSH terms: Stilbenes/chemistry
  17. Shimokawa Y, Akao Y, Hirasawa Y, Awang K, Hadi AH, Sato S, et al.
    J Nat Prod, 2010 Apr 23;73(4):763-7.
    PMID: 20192242 DOI: 10.1021/np9007987
    Gneyulins A (1) and B (2), two new stilbene trimers consisting of oxyresveratrol constituent units, and noidesols A (3) and B (4), two new dihydroflavonol-C-glucosides, were isolated from the bark of Gnetum gnemonoides. The structures and configurations of 1-4 were elucidated on the basis of 2D NMR correlations and X-ray analysis. Gneyulins A (1) and B (2) showed inhibition of Na(+)-glucose transporters (SGLT-1 and SGLT-2).
    Matched MeSH terms: Stilbenes/chemistry
  18. Agbo EN, Gildenhuys S, Choong YS, Mphahlele MJ, More GK
    Bioorg Chem, 2020 08;101:103997.
    PMID: 32554280 DOI: 10.1016/j.bioorg.2020.103997
    A series of furocoumarin-stilbene hybrids has been synthesized and evaluated in vitro for inhibitory effect against acetylcholinesterase (AChE), butyrylcholinestarase (BChE), β-secretase, cyclooxygenase-2 (COX-2), and lipoxygenase-5 (LOX-5) activities including free radical-scavenging properties. Among these hybrids, 8-(3,5-dimethoxyphenyl)-4-(3,5-dimethoxystyryl)furochromen-2-one 4h exhibited significant anticholinesterase activity and inhibitory effect against β-secretase, COX-2 and LOX-5 activities. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and an in vitro cell-based antioxidant activity assay involving lipopolysaccharide induced reactive oxygen species production revealed that 4h has capability of scavenging free radicals. Molecular docking into AChE, BChE, β-secretase, COX-2 and LOX-5 active sites has also been performed.
    Matched MeSH terms: Stilbenes/chemistry*
  19. Chan SY, Loh YC, Oo CW, Yam MF
    Bioorg Chem, 2020 11;104:104239.
    PMID: 33142420 DOI: 10.1016/j.bioorg.2020.104239
    The development of vasorelaxant as the antihypertensive drug is important as it produces a rapid and direct relaxation effect on the blood vessel muscles. Resveratrol (RV), as the most widely studied stilbenoid and the lead compound, inducing the excellent vasorelaxation effect through the multiple signalling pathways. In this study, the in vitro vascular response of the synthesized trans-stilbenoid derivatives, SB 1-8e were primarily evaluated by employing the phenylephrine (PE)-precontracted endothelium-intact isolated aortic rings. Herein we report trans-3,4,4'-trihydroxystilbene (SB 8b) exhibited surprisingly more than 2-fold improvement to the maximal relaxation (Rmax) of RV. This article also highlights the characterization of the aromatic protons in terms of their unique splitting patterns in 1H NMR.
    Matched MeSH terms: Stilbenes/chemistry
  20. Tan HH, Thomas NF, Inayat-Hussain SH, Chan KM
    PLoS One, 2020;15(5):e0223344.
    PMID: 32365104 DOI: 10.1371/journal.pone.0223344
    Stilbenes are a group of chemicals characterized with the presence of 1,2-diphenylethylene. Previously, our group has demonstrated that synthesized (E)-N-(2-(3, 5-dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) possesses potential chemopreventive activity specifically inducing NAD(P)H:quinone oxidoreductase 1 (NQO1) protein expression and activity. In this study, the cytoprotective effects of BK3C231 on cellular DNA and mitochondria were investigated in normal human colon fibroblast, CCD-18Co cells. The cells were pretreated with BK3C231 prior to exposure to the carcinogen 4-nitroquinoline 1-oxide (4NQO). BK3C231 was able to inhibit 4NQO-induced cytotoxicity. Cells treated with 4NQO alone caused high level of DNA and mitochondrial damages. However, pretreatment with BK3C231 protected against these damages by reducing DNA strand breaks and micronucleus formation as well as decreasing losses of mitochondrial membrane potential (ΔΨm) and cardiolipin. Interestingly, our study has demonstrated that nitrosative stress instead of oxidative stress was involved in 4NQO-induced DNA and mitochondrial damages. Inhibition of 4NQO-induced nitrosative stress by BK3C231 was observed through a decrease in nitric oxide (NO) level and an increase in glutathione (GSH) level. These new findings elucidate the cytoprotective potential of BK3C231 in human colon fibroblast CCD-18Co cell model which warrants further investigation into its chemopreventive role.
    Matched MeSH terms: Stilbenes/chemistry
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