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Inhibitory effect of lignans from the rhizomes of Coptis japonica var. dissecta on tumor necrosis factor-alpha production in lipopolysaccharide-stimulated RAW264.7 cells.

The inhibitory effect of 10 lignan constituents isolated from the rhizomes of Coptis japonica var. dissecta on tumor necrosis factor (TNF)-alpha production in lipopolysaccharide (LPS)-stimulated macrophage cell line (RAW264.7 cells) has been studied. Among them, pinoresinol, woorenoside-V and lariciresinol glycoside showed significant inhibitory activities in the range from 37% to 55% at the concentration of 25 micrograms/ml. The results are first report that the lignans isolated from Coptis japonica inhibit TNF-alpha production, and suggest that the lignan components may partly participate in antiinflammatory and antiallergic effect of Coptis japonica through the inhibition of TNF-alpha production.

3',5'-Cyclic-AMP Phosphodiesterases↗

Naturally occurring lignans efficiently induce apoptosis in colorectal tumor cells.

Plant-derived lignans caused cell loss by apoptosis in colorectal adenoma and carcinoma cells. Nordihydroguaiaretic acid (NDGA), commonly used for the inhibition of lipoxygenase isoenzymes, showed the strongest growth inhibition with an IC50 of 1.9+/-0.5 microg followed by epiashantin (IC50=9.8+/-4.5 microM) and arctigenin (IC50=16.5+/-8.5 microM). The lignans caused a time- and dose-dependent loss of mitochondrial membrane potential (MMP), down regulation of the anti-apoptotic protein bcl(xl) and an increase of the apoptotic index. The time interval until loss of MMP and down modulation of bcl(xl) became evident correlated with the efficiency of growth inhibition by NDGA, epiashantin and yangambin. Bcl2 and caspase 3 were not involved. NDGA also induced a shift of the culture population to the G2/M phase of the cell cycle. With respect to these results, naturally occurring lignans could be useful in the therapy and chemoprevention of colorectal tumors.

Adenoma↗

Dietary lignan intakes and risk of breast cancer by tumor estrogen receptor status.

We examined the association of dietary lignan intake with estrogen receptor negative (ER-) and ER positive (ER+) breast cancer risk in a breast cancer case-control study. Among premenopausal women only, there was a reduced risk of ER- breast cancer for those in the highest compared to the lowest quartile of lignan intake suggesting that the observed negative association of lignans with breast cancer may be limited to ER- tumors.

Adult↗

Syntheses of C(18) dibenzocyclooctadiene lignan derivatives as anti-HBsAg and anti-HBeAg agents.

(+)-Gomisin K(3) (1) and kadsurarin (2) were isolated from Schizandra arisanensis and Kadsura matsudai, respectively, and a series of C(18) dibenzocyclooctadiene lignan analogues (5-20) derived from 1 and 2 were synthesized. Esterified derivatives of 1 and 2 were evaluated for inhibitory activity against human type B hepatitis with surface antigen (HBsAg) and e antigen (HBeAg). Most of the analogues (5-8, 10, 12-13) derived from 1 exhibited higher anti-HBsAg effects and lower toxicity, and 6, 7, 8 and 12 also showed higher anti-HBeAg activity. Among these active C(18) dibenzocyclooctadiene lignan analogues, the lignan with a but-3-enoyl group (6) exhibited the most active inhibition.

Antiviral Agents↗

Dibenzo[a,c]cyclooctadiene lignans of the genus Schisandra: importance, isolation and determination.

The drug Wuweizi (dried fruits of Schisandra chinensis or S. sphenantherd) is one of important medicinal means used in the Oriental medicine. The lignans of dibenzo[a,c]cyklooctadiene type are major constituents, a volatile oil with mono- and ses-quiterpens, an oil, organic acids and small amounts of additional compounds are also present. The content of major lignans (schizandrin, deoxyschizandrin, gomisin A, gomisin N, gamma-schizandrin, wuweizisu C) in commercially available drugs ranges usually between 3 and 5%. The present paper biefly comments the isolation and biological activity of the lignans and is especially concerned with analytical methods (TLC and HPLC) for the determination of the drug fingerprint and methods for the determination of constituents in drugs, mixtures and biological materials. HPLC methods using RP-silica bonded phases and diluted methanol, acetonitrile (or a mixture of both), are most important for these purposes. Electromigration methods are less suitable and the importance of hyphenation procedures is practically negligible.

Chromatography, High Pressure Liquid↗

Application of capillary electrochromatography using macroporous polyacrylamide columns for the analysis of lignans from seeds of Schisandra chinensis.

Capillary electrochromatography (CEC) using polymer-based monolithic stationary phase has been developed as a promising method for the determination of lignans of Schisandra chinensis. The columns were prepared by in situ copolymerisation of acrylamide, N,N'-methylenebisacrylamide, vinylsulfonic acid and lauryl acrylate in presence of poly(ethylene glycol) as a porogenic agent. The columns [33 cm (24.5 cm effective length) x 75 microm I.D.] were successfully used to analyse and quantify the major lignans in extract of the seeds of Schisandra chinensis. Good separations were achieved in less than 35 min. The calibration graphs were linear in the range 0.025-1.0 mg/ml of given lignan with correlation coefficients between 0.9951 and 0.9996. The inter-day reproducibility of the peak area were below 3.9% and the inter-day reproducibility of the migration time were below 4.2%. The results of quantitative CEC analyses were compared with those obtained by reversed-phase HPLC, the levels of schizandrin, gomisin A, gomisin N and wuweizisu C determined by CEC were in a good agreement with those determined by HPLC.

Acrylic Resins↗

Lignans causing photodiscoloration of Tsuga heterophylla: 8-hydroxy-oxomatairesinol from sapwood.

A lignan, (8S,8'S,)-(+)-8-hydroxy-oxomatairesinol, has been isolated from the sapwood of Tsuga heterophylla (western hemlock, Pinaceae). The known lignans matairesinol, lariciresinol and secoisolariciresinol were also obtained. The structure of the compound was established by 1D and 2D NMR spectroscopy. Results of the light-irradiation test of the lignans from T. heterophylla are also reported.

Chromatography, High Pressure Liquid↗

Cytotoxic lignans from Formosan Hernandia nymphaeifolia.

A new dibenzylbutyrolactone lignan, (--)-6-hydroxyyatein, along with two new furanoid lignans, (--)-hernone [(2R,3S,4R)-(--)-3-hydroxymethyl -4-(3",4",5"-trimethoxybenzoyl)-2-(3,4-dimethoxyphenyl) tetrahydrofuran] and (--)-nymphone [(2R,3S,4R)-(--)-3-hydroxymethyl-4-(3",4",5"-trimethoxybenzoyl)-2- (3,4-methylenedioxyphenyl)tetrahydrofuran], have been isolated and characterized from the trunk bark of Formosan Hernandia nymphaeifolia. The structures of these compounds were determined by means of spectral analyses. These three lignans exhibited cytotoxic activities against P-388, KB16, A549 and HT-29 cell lines.

Animals↗

alpha,beta-Dibenzyl-gamma-butyrolactone lignan alcohols: total synthesis of (+/-)-7'-hydroxyenterolactone, (+/-)-7'-hydroxymatairesinol and (+/-)-8-hydroxyenterolactone.

Two trans-alpha,beta-dibenzyl-gamma-butyrolactone lignans carrying a hydroxyl group at the beta-benzylic carbon atom and a alpha-hydroxy alpha,beta-dibenzyl-gamma-butyrolactone lignan were synthesized in racemic form using the tandem conjugate addition reaction to construct the basic lignan skeleton. Subsequent reaction steps involved either a catalytic reduction of the regenerated keto group to the alcohol, or a hydrogenolysis to benzylic methylene followed by lactone enolate formation and oxidation to give the alpha-hydroxybutyrolactones. These procedures were applied for the synthesis of 7'-hydroxyenterolactones and 7'-hydroxymatairesinols, and 8-hydroxyenterolactones, respectively. The diastereomeric mixtures of these compounds were separated either by HPLC techniques or column chromatography and the structures were elucidated using NMR spectroscopy.

Alcohols↗

Experimental studies on lignans and cancer.

Mammalian lignans are produced from plant precursors such as secoisolariciresinol diglycoside (SDG) and matairesinol via the action of bacteria in the human or animal colon. While precursors are found in many plant foods, flaxseed is the richest source of SDG and was therefore used as a model to determine the anti-cancer effects of lignans. This paper reviews the experimental studies in animals and humans demonstrating the anti-cancer effects of flaxseed and its SDG as well as other studies relevant to the clinical use of lignans, such as those on their food sources, bio-availability and safety.

Animals↗

Regulation of c-fos transcription by chemopreventive isoflavonoids and lignans in MDA-MB-468 breast cancer cells.

Isoflavonoids and lignans are diet constituents with chemopreventive properties. We compared the ability of the isoflavonoids genistein and equol, the lignans enterodiol, enterolactone and nordihydroguaiaretic acid (NDGA) and the lignan metabolite methyl p-hydroxyphenyllactate to interfere with mitogenic and tumour promotional signal transduction pathways. Their effects on c-fos mRNA levels after induction by either epidermal growth factor (EGF) or the tumour promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) was measured in human breast cancer-derived MDA-MB-468 cells. Of the six agents, only genistein decreased EGF-induced, c-fos transcription (by 63% compared to control at 100 mumol/l). In contrast, both genistein and equol at 100 mumol/l decreased TPA-induced c-fos levels, by 75 and 67%, respectively. NDGA and methyl p-hydroxyphenyllactate did not inhibit TPA mediated c-fos transcription and enterolactone and enterodiol had only a weak inhibitory effect. NDGA at 0.1-10 mumol/l increased c-fos mRNA levels. None of the agents inhibited protein kinase C and only genistein inhibited EGF receptor-linked protein tyrosine kinase obtained from MDA-MB-468 cells, with an IC50 of 60 mumol/l. NDGA and genistein arrested cell colony formation potently, genistein was 15-fold more growth-inhibitory than equol. The results suggest that both genistein and equol interfere similarly with TPA-induced signal transduction pathways. Inhibition by genistein of EGF-induced c-fos mRNA transcription is probably related to its interruption of EGF receptor-linked protein tyrosine kinase, whereas genistein-induced growth arrest is not. If ability to antagonise phorbol ester effects is important for chemopreventive efficacy, equol and genistein might be equi-efficacious chemopreventors, whereas enterolactone, enterodiol and NDGA should be much less potent. If phorbol ester antagonism together with antimitogenic activity determine optimal chemopreventive activity of this type of agent, genistein would be more potent than equol.

Breast Neoplasms↗

Anti-AIDS agents--XXVI. Structure-activity correlations of gomisin-G-related anti-HIV lignans from Kadsura interior and of related synthetic analogues.

Bioactivity-directed fractionation of an ethanolic extract of the stems of Kadsura interior led to the isolation and identification of 12 known lignans (1-12). Seven of these compounds (1, 6, 8-12) were active as anti-HIV agents. Gomisin-G (11) exhibited the most potent anti-HIV activity with EC50 and therapeutic index (TI) values of 0.006 microgram/mL and 300, respectively. Schisantherin-D (6), kadsuranin (8), and schisandrin-C (10) showed good activity with EC50 values of 0.5, 0.8, and 1.2 micrograms/mL, and TI values of 110, 56, and 33.3, respectively. Ten related synthetic biphenyl compounds, five variously substituted bismethylenedioxy, dimethoxy, and dimethoxycarbonyl isomers (18-22) and five brominated derivatives (23-27) also were evaluated for inhibitory activity against HIV-1 replication in acutely infected H9 cells. The total syntheses of two new isomers (21 and 22) are reported for the first time. The anti-HIV data indicated that the relative position and types of substituents on the phenolic hydroxy groups of either the natural lignans or the synthetic biphenyl compounds rather than the numbers of bromine(s) on the aromatic rings are of primary importance. In the cyclooctane ring of the natural lignans, the position and substitution of hydroxy groups are also important to enhanced anti-HIV activity.

Anti-HIV Agents↗

Potent inhibition of lipopolysaccharide-inducible nitric oxide synthase expression by dibenzylbutyrolactone lignans through inhibition of I-kappaBalpha phosphorylation and of p65 nuclear translocation in macrophages.

AIMS: Arctigenin and demethyltraxillagenin, dibenzylbutyrolactone lignans, are phenylpropanoid metabolites with antioxidant and anti-inflammatory activities. The effects of arctigenin and demethyltraxillagenin on the nuclear factor-kappaB (NF-kappaB)-mediated inducible nitric oxide synthase (iNOS, EC1.14.13.39) gene expression were studied in Raw264.7 cells. METHODS: Activation of NF-kappaB was determined by gel mobility shift assay, immunocytochemistry and immunoblot analysis of I-kappaBalpha. Expression of the iNOS gene was assessed by Northern and Western blot analyses. NO production was monitored by chemiluminescent detection using a nitric oxide analyzer. RESULTS: Arctigenin (1 microM) inhibited lipopolysaccharide (LPS)-inducible nuclear NF-kappaB activation and nuclear translocation of p65, which was accompanied by inhibition of I-kappaBalpha phosphorylation, whereas demethyltraxillagenin was less active. LPS-inducible increase in the iNOS mRNA was 80-90% inhibited by 0.01-1 microM arctigenin, whereas similar extents of inhibition were noted by 50-100 microM demethyltraxillagenin. Immunoblot analysis revealed that arctigenin potently inhibited the induction of iNOS by LPS (IC50 < 0.01 microM). The IC50 value of demethyltraxillagenin was approximately 50 microM. Production of nitrite and nitrate by LPS in culture medium was also comparably suppressed by the lignans. CONCLUSION: These results demonstrated that arctigenin potently inhibited LPS-inducible iNOS expression in murine macrophages through suppression of I-kappaBalpha phosphorylation and nuclear translocation of p65. Potent inhibition of LPS-inducible NO production in macrophages may constitute anti-inflammatory effects of the dibenzylbutyrolactone lignans.

Animals↗

Studies on the metabolism of the plant lignans secoisolariciresinol and matairesinol.

The plant lignans secoisolariciresinol and matairesinol occur in numerous foods such as oil seeds, whole grains, vegetables, and fruits. We have studied the hitherto unknown oxidative metabolism of secoisolariciresinol and matairesinol in hepatic microsomes from untreated and Aroclor 1254-induced Wistar rats and from humans. Five oxidative metabolites of secoisolariciresinol and 10 oxidative metabolites of matairesinol were detected in rat liver microsomes, and their chemical structures were elucidated. The pathways in the metabolism of both secoisolariciresinol and matairesinol included aliphatic and aromatic hydroxylation, whereas oxidative demethylation was only observed for matairesinol. Human hepatic microsomes were able to metabolize secoisolariciresinol whereas matairesinol was only poorly metabolized. This study clearly shows that secoisolariciresinol and matairesinol are substrates of cytochrome P450-mediated metabolism. However, from preliminary experiments with rats dosed orally with secoisolariciresinol and matairesinol, it appears that the intestinal absorption and subsequent oxidative metabolism of these plant lignans occur only to a very small extent due to the highly efficient conversion of secoisolariciresinol and matairesinol to the mammalian lignans enterodiol and enterolactone by the gut microflora.

Animals↗

Synthesis and cytotoxicity of novel lignans.

In this study the syntheses of 11 novel lignans are described. Their cytotoxicities are studied in GLC4, a human small cell lung carcinoma cell line, using the microculture tetrazolium (MTT) assay. Ten of these compounds were substituted with a menthyloxy group on the 5-position of the lactone. These compounds can easily be prepared in (novel) 'one-pot', three- or four-step syntheses. In addition, methods for controlling the stereogenic centers are described. Furthermore, five naturally occurring podophyllotoxin-related compounds were tested. The cytotoxicities of all lignan compounds, and of three non-lignan intermediates originating from the syntheses, were compared with the clinically applied anticancer agents etoposide, teniposide, and cisplatin. Most compounds showed moderate to high activities against GLC4, and two of the compounds containing a menthyloxy group showed activities comparable to the reference cytotoxic agents.

Antineoplastic Agents↗

A new lariciresinol-type butyrolactone lignan derived from hydroxymatairesinol and its identification in spruce wood.

When the natural lignan hydroxymatairesinol (1) was treated with an alkaline aqueous solution, it partially rearranged to isomeric forms of a lariciresinol-type butyrolactone lignan. The two major diastereomers formed (2 and 3) were isolated by column and medium-pressure chromatography, and their structures were elucidated by MS and NMR techniques. These previously unknown butyrolactone lignans were identified as naturally occurring in spruce knotwood by GC, GC-MS, and HPLC-ESI MS/MS analyses. The formation of isohydroxymatairesinol (2) and epi-isohydroxymatairesinol (3) from hydroxymatairesinol (1), and their detection in rat urine after administration of 1, is discussed.

4-Butyrolactone↗

Lignan derivatives and a norditerpene from the seeds of Vitex negundo.

A new phenyldihydronaphthalene-type lignan, vitedoin A (1), a new phenylnaphthalene-type lignan alkaloid, vitedoamine A (2), and a new trinorlabdane-type diterpene, vitedoin B (3), were isolated from the seeds of Vitex negundo along with five known lignan derivatives (4-8). Their chemical structures were determined mainly on the basis of NMR and MS data. Compounds 1, 2, and 4-7 showed stronger antioxidative activity than alpha-tocopherol using the ferric thiocyanate method. Compounds 1, 2, and 4-7 showed higher radical-scavenging effect on the stable free radical, 1,1-diphenyl-2-picrylhydrazyl, than L-cysteine.

Antioxidants↗

Lignans and their degraded derivatives from Sarcostemma acidum.

Four lignans, sacidumlignans A-D (1-4), and two degraded lignan derivatives, sacidumols A (5) and B (6), along with four known compounds, (+)-pinoresinol, 9alpha-hydroxypinoresinol, perforatic acid, and peucenine-7-O-methyl ether, were isolated from the ethanolic extract of the whole plant of Sarcostemma acidum. The structures and relative configuration of these new compounds were elucidated on the basis of spectroscopic and chemical data, especially 2D NMR techniques. Sacidumlignan D (4) was assigned as a rearranged tetrahydrofuran lignan with an unprecedented skeleton. Sacidumlignan A (1) showed moderate antimicrobial activities against two Gram-positive bacteria in vitro.

Anti-Bacterial Agents↗