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Analgesic activity of the lignans from Lychnophora ericoides.

Lychnophora ericoides is a Brazilian medicinal plant that is commercially available as an analgesic and anti-inflammatory agent. The extract from roots, which yielded 10 lignans, showed analgesic activity in the mouse writhing test and the lignan, cubebin, was one of the most active. Anti-inflammatory and anti-pyretic activities from cubebin (10 mg/kg) revealed no significant effects. In addition two previously unknown methyl clusin derivatives are reported.

Analgesics↗

Dibenzylbutane and aryltetralone lignans from seeds of Virola sebifera.

Two lignans rel-(8R, 8'R)-3,4:3',4'-bis-(methylenedioxy)-7.7'-dioxo-lignan and (7'R,8'S,8S)-2'-hydroxy-3,4:4',5'-bis-(methylenedioxy)-7-oxo-2,7'-cyclolignan were isolated from seeds of Virola sebifera. The cyclolignan showed two atropisomers as determined by 1H NMR spectroscopy at low temperature.

Lignans↗

Lignans from Phyllanthus urinaria.

Chemical investigation on the aerial and the root parts of Phyllanthus urinaria L. culminated in the isolation of four lignans, namely 5-demethoxyniranthin, urinatetralin, dextrobursehernin, urinaligran, together with nine known lignans. Their structures, including the absolute stereochemistry, were elucidated by spectral analysis (NMR and CD) and chemical correlation.

Circular Dichroism↗

Two lignan dimers from bamboo stems (Phyllostachys edulis).

Phyllostadimers A and B, two bis-lignans in which the two lignan units are directly connected by a C-C bond, were isolated from stems of bamboo, Phyllostachys edulis. Their structures were determined on the basis of spectral evidence. In addition, 14 known compounds were also obtained throughout the investigation. Phyllostadimer A significantly inhibited liposomal lipid peroxidation.

Antioxidants↗

Metabolism of isoflavones and lignans by the gut microflora: a study in germ-free and human flora associated rats.

We have investigated the metabolism of isoflavones and lignans in germ-free (GF) rats and rats associated with human faecal bacteria (human flora associated [HFA] rats), in order to provide unequivocal evidence for the role of the gut microflora in the absorption and metabolism of these phytoestrogens. Furthermore, we have investigated whether certain metabolic characteristics (high equol-producing and low equol-producing status) of human intestinal floras can be transferred to GF rats. Germ-free rats fed a soy-isoflavone containing diet excreted large quantities of daidzein and genistein in urine indicating that the gut microflora is not required for the absorption of isoflavones. The isoflavone metabolites equol, O-desmethylangolensin and the lignan enterolactone were not detectable in urine from the GF rats, but were present in HFA rat urine, indicating that they were products of gut microflora activity. Colonization of GF rats with a faecal flora from a human subject with the capacity to convert daidzein to equol, resulted in the rats excreting substantial amounts of the metabolite. In contrast, equol was undetectable in urine of HFA rats associated with a faecal flora from a low equol-producing subject. The results therefore show that the inability of some subjects to produce equol is a consequence of the lack of specific components of the gut microflora.

Animals↗

Plasma insulin-like growth factor I levels in rats are reduced by dietary supplementation of flaxseed or its lignan secoisolariciresinol diglycoside.

Flaxseed and its lignan secoisolariciresinol diglycoside (SDG) inhibit mammary tumor development in rats. Increased plasma insulin-like growth factor I (IGF-I) concentrations are associated with increased breast cancer risk. Therefore, the effect of flaxseed (5%) or SDG (1.5 mg/day) supplementation on plasma IGF-I levels was examined in rats treated with or without N-methyl-N-nitrosourea (MNU). In MNU-free rats, flaxseed and SDG reduced plasma IGF-I levels, which were inversely related to urinary lignan excretion. Only flaxseed significantly reduced plasma IGF-I concentrations in MNU-treated rats. The anticancer effect of flaxseed and SDG may be related, in part, to reductions in plasma IGF-I.

Animals↗

Lack of significant inhibitory effects of a plant lignan tracheloside on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary carcinogenesis in female Sprague-Dawley rats.

Tracheloside, one of the plant lignans which can be extracted from the debris after safflower oil is produced from the seeds of Carthamus tinctorious, is an analogue of another plant lignan, arctiin, the side-chain C-2 of the five-membered ring being changed from a hydrogen to a hydroxyl group. We have already demonstrated that arctiin has chemopreventive effect on mammary carcinogenesis. Therefore, chemopreventive effects of tracheloside on the initiation or post-initiation period of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary carcinogenesis in female rats were examined. For initiation, female Sprague-Dawley (SD) rats at the 6 weeks of age were given intragastric administrations of 100 mg/kg body weight of PhIP once a week for 8 weeks. The animals were treated with 0.2 or 0.02% tracheloside during or after this carcinogen exposure. Control rats were fed basal diet with PhIP initiation or 0.2% tracheloside or basal diet alone without initiation throughout the experimental period. All surviving animals were necropsied at the week 52 of administration. There were no clear treatment-related changes with statistical significance in all parameters for mammary carcinomas measured in this experiment. These results indicate that tracheloside may not exert significant effects on PhIP-induced mammary carcinogenesis at least under the present experiment condition.

4-Butyrolactone↗

Measurement and metabolism of isoflavonoids and lignans in the human male.

Asian men, who consume a low fat/high fibre soya-based diet, have very much lower incidence of prostate cancer than men from North America and Europe. The soya bean is a rich source of the isoflavonic phyto-oestrogens, daidzein, genistein and equol, compounds which may be cancer-protective in Asian populations. The lignans, enterolactone and enterodiol, plant oestrogens derived from cereals and vegetables, may act in a similar manner in vegetarian men. We report here on the measurement of isoflavonoids and lignans, by gas chromatography-mass spectrometry, in prostatic fluid of men from Asia and Europe and also on the metabolism of these compounds in Western men following dietary supplementation.

Adult↗

A new prenylated arylnaphthalene lignan from Haplophyllum myrtifolium.

A novel prenylated arylnaphthalene lignan, 7-O-(3-methyl-2-butenyl)isodaurinol, was isolated from Haplophyllum myrtifolium and identified on the basis of detailed spectral analyses, including 2D-NMR spectrometry. The known furoquinoline alkaloids, dictamnine, robustine, gamma-fagarine and skimmianine, the aryltetralin lignan (-)-1beta-polygamain and the flavone chrysosplenetin were isolated from the same source.

Humans↗

Mammalian lignan formation in rats fed a wheat bran diet.

The dietary origin of lignan phytoestrogens is still poorly understood more than 20 years after their discovery in human urine. Their level in urine has been associated with the consumption of dietary fiber. This paper reports the study of the excretion of enterolactone, assayed by a time-resolved fluoroimmunoassay, in rats fed a diet supplemented with 15% wheat bran, one of the main sources of fiber in Western countries. Enterolactone excretion regularly increased during the two weeks of the diet to reach a value of 45 nmol/day. The level of excretion also increased upon preadaptation to ferulic acid, structurally related to secoisolariciresinol, an established precursor of enterolactone in flaxseeds, and decreased upon preadaptation to potato starch rich in fiber. These results show that the formation of lignans from wheat bran is influenced by the diet, possibly because of an adaptation of the colonic microflora.

4-Butyrolactone↗

Abscisic acid related compounds and lignans in prunes (Prunus domestica L.) and their oxygen radical absorbance capacity (ORAC).

Four new abscisic acid related compounds (1-4), together with (+)-abscisic acid (5), (+)-beta-D-glucopyranosyl abscisate (6), (6S,9R)-roseoside (7), and two lignan glucosides ((+)-pinoresinol mono-beta-D-glucopyranoside (8) and 3-(beta-D-glucopyranosyloxymethyl)-2- (4-hydroxy-3-methoxyphenyl)-5-(3-hydroxypropyl)-7-methoxy-(2R,3S)-dihydrobenzofuran (9)) were isolated from the antioxidative ethanol extract of prunes (Prunus domestica L.). The structures of 1-4 were elucidated on the basis of NMR and MS spectrometric data to be rel-5-(3S,8S-dihydroxy-1R,5S-dimethyl-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (1), rel-5-(3S,8S-dihydroxy-1R,5S-dimethyl-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid 3'-O-beta-d-glucopyranoside (2), rel-5-(1R,5S-dimethyl-3R,4R,8S-trihydroxy-7-oxa-6-oxobicyclo[3,2,1]oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (3), and rel-5-(1R,5S-dimethyl-3R,4R,8S-trihydroxy-7-oxabicyclo[3,2,1]- oct-8-yl)-3-methyl-2Z,4E-pentadienoic acid (4). The antioxidant activities of these isolated compounds were evaluated on the basis of oxygen radical absorbance capacity (ORAC). The ORAC values of abscisic acid related compounds (1-7) were very low. Two lignans (8 and 9) were more effective antioxidants whose ORAC values were 1.09 and 2.33 micromol of Trolox equiv/micromol, respectively.

Abscisic Acid↗

Bioactive lignans from a cultivar of Helianthus annuus.

A bioassay-guided fractionation of water extracts from Helianthus annuus cv. SH-222 was carried out. Ten lignans and a phenylpropanoid were isolated from the polar bioactive fractions of H. annuus. This study is the first to report lignans as constituents of sunflower and is the first time that tanegool has been isolated as a natural aglycone. Additionally, we report biological activities of the isolated compounds. The general bioactivity has been evaluated using the wheat coleoptiles bioassay. The phytotoxic activities of compounds pinoresinol, lariciresinol, dihydro-dehydrodiconiferilic alcohol, and l-(4'-hydroxy-3'-methoxyphenyl)-2-[4' '-(3hydroxypropyl)-2' '-methoxyphenoxy]propane-l,3-diol were also evaluated in a bioassay on the standard target species. The structure-activity relationships are discussed.

Chemical Fractionation↗

Optimization of a liquid chromatography-tandem mass spectrometry method for quantification of the plant lignans secoisolariciresinol, matairesinol, lariciresinol, and pinoresinol in foods.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of the four major enterolignan precursors [secoisolariciresinol, matairesinol, lariciresinol, and pinoresinol] in foods. The method consists of alkaline methanolic extraction, followed by enzymatic hydrolysis using Helix pomatia (H. pomatia) beta-glucuronidase/sulfatase. H. pomatia was selected from several enzymes based on its ability to hydrolyze isolated lignan glucosides. After ether extraction samples were analyzed and quantified against secoisolariciresinol-d8 and matairesinol-d6. The method was optimized using model products: broccoli, bread, flaxseed, and tea. The yield of methanolic extraction increased up to 81%, when it was combined with alkaline hydrolysis. Detection limits were 4-10 microg/(100 g dry weight) for solid foods and 0.2-0.4 microg/(100 mL) for beverages. Within- and between-run coefficients of variation were 6-21 and 6-33%, respectively. Recovery of lignans added to model products was satisfactory (73-123%), except for matairesinol added to bread (51-55%).

Butylene Glycols↗

New lignans from the perisperm of Sesamum indicum.

A procedure, based on XAD-4 adsorption resin, which permits the obtainment of enriched polyphenolic extracts from Sesamum indicum perisperm (coat) has been developed. Chemical analysis of the obtained extracts led to the identification of 16 lignans. Among them, two new lignans, (+)-saminol and (+)-episesaminone-9-O-beta-D-sophoroside, have been isolated. Additionally, the relative stereochemistry of (-)-sesamolactol, previously reported as todolactol A epimer, has been unequivocally defined using X-ray crystallography. The structures of all new compounds were determined by spectroscopic methods, mainly by the concerted application of 1D and 2D NMR techniques (HMQC, HMBC, and NOESY) and mass spectroscopy.

Crystallography, X-Ray↗

1-Arylnaphthalene lignan: a novel scaffold for type 5 phosphodiesterase inhibitor.

1-Arylnaphthalene lignan, which had been reported as a PDE4 inhibitor by Iwasaki, was disclosed as a new structural class of PDE5 inhibitors. The structural requirements for potent and specific PDE5 inhibition were revealed in a 1-arylnaphthalene lignan series, in which 1-(3-bromo-4, 5-dimethoxyphenyl)-5-chloro-3-[4-(2-hydroxyethyl)-1-piperazinylcarbon yl]-2-(methoxycarbonyl)naphthalene hydrochloride (27q) showed the most potent and specific inhibition (PDE5 inhibition IC50 = 6.2 nM, selectivity for PDE5 against PDE1, -2, -3, and -4 >16 000). It is noteworthy that 27q has the best selectivities against PDE isoforms among PDE5 inhibitors so far reported. Compound 27q exhibited almost the same relaxant effects on rat aortic rings as sodium 1-[6-chloro-4-[(3, 4-methylenedioxybenzyl)amino]quinazolin-2-yl]piperidine-4-ca rboxylate (35) (27q, EC50 = 0.10 microM; 35, EC50 = 0.20 microM) and was selected for further biological evaluation.

3',5'-Cyclic-GMP Phosphodiesterases↗

Synthesis and biological evaluation of dihydrobenzofuran lignans and related compounds as potential antitumor agents that inhibit tubulin polymerization.

A series of 19 related dihydrobenzofuran lignans and benzofurans was obtained by a biomimetic reaction sequence involving oxidative dimerization of p-coumaric, caffeic, or ferulic acid methyl esters, followed by derivatization reactions. All compounds were evaluated for potential anticancer activity in an in vitro human disease-oriented tumor cell line screening panel that consisted of 60 human tumor cell lines arranged in nine subpanels, representing diverse histologies. Leukemia and breast cancer cell lines were relatively more sensitive to these agents than were the other cell lines. Compounds 2c and 2d, but especially 2b (methyl (E)-3-¿2-(3, 4-dihydroxyphenyl)-7-hydroxy-3-methoxycarbonyl-2, 3-dihydro-1-benzofuran-5-ylprop-2-enoate), the dimerization product of caffeic acid methyl ester, containing a 3',4'-dihydroxyphenyl moiety and a hydroxyl group in position 7 of the dihydrobenzofuran ring, showed promising activity. The average GI(50) value (the molar drug concentration required for 50% growth inhibition) of 2b was 0.3 microM. Against three breast cancer cell lines, 2b had a GI(50) value of <10 nM. Methylation, reduction of the double bond of the C(3)-side chain, reduction of the methoxycarbonyl functionalities to primary alcohols, or oxidation of the dihydrobenzofuran ring to a benzofuran system resulted in a decrease or loss of cytotoxic activity. Compound 2b inhibited mitosis at micromolar concentrations in cell culture through a relatively weak interaction at the colchicine binding site of tubulin. In vitro it inhibited tubulin polymerization by 50% at a concentration of 13 +/- 1 microM. The 2R, 3R-enantiomer of 2b was twice as active as the racemic mixture, while the 2S,3S-enantiomer had minimal activity as an inhibitor of tubulin polymerization. These dihydrobenzofuran lignans (2-phenyl-dihydrobenzofuran derivatives) constitute a new group of antimitotic and potential antitumor agents that inhibit tubulin polymerization.

Antineoplastic Agents↗

Naphthalene analogues of lignans.

The methodology for the synthesis of podophyllotoxin and thuriferic acid-type lignans has been applied to derivatives carrying a naphthalene moiety. Starting from the 1,3-dithiane of 2-naphthaldehyde afforded the expected analogues in the 2,1-naphthalene series. The preferred conformations of these compounds are influenced by the bulky naphthalene system. By contrast, 1,8-bridged products were obtained from the 1,3-dithiane of 1-naphthaldehyde. In this series, polycyclic naphthalene lignan analogues were isolated after deprotection and/or desulfurization reactions. The cyclizations produced in this process are due to the proximity between the 3,4,5-trimethoxyphenyl moiety and the reacting C-2 of the 1,3-dithiane ring.

Carbazoles↗

Coumarins with monoamine oxidase inhibitory activity and antioxidative coumarino-lignans from Hibiscus syriacus.

A previously undescribed coumarin and a new coumarino-lignan, together with the known compounds scopoletin and cleomiscosins A, C, and D, have been isolated from the root bark of Hibiscus syriacus, and their structures were assigned on the basis of various spectral studies. The coumarin analogue and scopoletin inhibited monoamine oxidase with moderate IC(50) values. The new coumarino-lignan and cleomiscosin C showed lipid peroxidation inhibitory activity comparable to vitamin E.

Animals↗