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At least 19 recordsLinked to original sources
PubMed2006

Nondestructive determination of lignans and lignan glycosides in sesame seeds by near infrared reflectance spectroscopy.

Sesame (Sesamum indicum L.) contains abundant lignans including lipid-soluble lignans (sesamin and sesamolin) and water-soluble lignan glycosides (sesaminol triglucoside and sesaminol diglucoside) related to antioxidative activity. In this study, near infrared reflectance spectroscopy (NIRS) was used to develop a rapid and nondestructive method for the determination of lignan contents on intact sesame seeds. Ninety-three intact seeds were scanned in the reflectance mode of a scanning monochromator. This scanning procedure did not require the pulverization of samples, allowing each analysis to be completed within minutes. Reference values for lignan contents were obtained by high-performance liquid chromatography analysis. Calibration equations for lignans (sesamin and sesamolin) and lignan glycosides (sesaminol triglucoside and sesaminol diglucoside) contents were developed using modified partial least squares regression with internal cross-validation (n = 63). The equations obtained had low standard errors of cross-validation and moderate R2 (coefficient of determination in calibration). The prediction of an external validation set (n = 30) showed significant correlation between reference values and NIRS predicted values based on the SEP (standard error of prediction), bias, and r2 (coefficient of determination in prediction). The models developed in this study had relatively higher values (more than 2.0) of SD/SEP(C) for all lignans and lignan glycosides except for sesaminol diglucoside, which had a minor amount, indicating good correlation between the reference and the NIRS estimate. The results showed that NIRS, a nondestructive screening method, could be used to rapidly determine lignan and lignan glycoside contents in the breeding programs for high quality sesame.

Calibration↗
PubMed2001

In vitro metabolism of plant lignans: new precursors of mammalian lignans enterolactone and enterodiol.

The metabolism of the plant lignans matairesinol, secoisolariciresinol, pinoresinol, syringaresinol, arctigenin, 7-hydroxymatairesinol, isolariciresinol, and lariciresinol by human fecal microflora was investigated to study their properties as mammalian lignan precursors. The quantitative analyses of lignan precursors and the mammalian lignans enterolactone and enterodiol were performed by HPLC with coulometric electrode array detector. The metabolic products, including mammalian lignans, were characterized as trimethylsilyl derivatives by gas chromatography-mass spectrometry. Matairesinol, secoisolariciresinol, lariciresinol, and pinoresinol were converted to mammalian lignans only. Several metabolites were isolated and tentatively identified as for syringaresinol and arctigenin in addition to the mammalian lignans. Metabolites of 7-hydroxymatairesinol were characterized as enterolactone and 7-hydroxyenterolactone by comparison with authentic reference compounds. A metabolic scheme describing the conversion of the most abundant new mammalian lignan precursors, pinoresinol and lariciresinol, is presented.

4-Butyrolactone↗
PubMed1999

Antioxidant activity of the flaxseed lignan secoisolariciresinol diglycoside and its mammalian lignan metabolites enterodiol and enterolactone.

The antioxidant activities of the flaxseed lignan secoisolariciresinol diglycoside (SDG) and its mammalian lignan metabolites, enterodiol (ED) and enterolactone (EL), were evaluated in both lipid and aqueous in vitro model systems. All three lignans significantly (p < or = 0.05) inhibited the linoleic acid peroxidation at both 10 and 100 microM over a 24-48 h of incubation at 40 degrees C. In a deoxyribose assay, which evaluates the non site-specific and site-specific Fenton reactant-induced *OH scavenging activity, SDG demonstrated the weakest activity compared to ED and EL at both 10 and 100 microM; the greatest *OH scavenging for ED and EL was observed at 100 microM in both assays. The incubation of pBR322 plasmid DNA with Fenton reagents together with SDG, ED or EL showed that the inhibition of DNA scissions was concentration dependent. The greatest non site-specific activity of lignans was at 100 microM, thus, confirming the results of the deoxyribose test. In contrast, the protective effect of SDG and EL in the site-specific assay was lost and that of ED was minimal. Therefore, the results indicate a structure-activity difference among the three lignans with respect to specific antioxidant efficacy. All three lignans did not exhibit reducing activity compared to ascorbic acid, therefore, did not possess indirect prooxidant activity related to potential changes in redox state of transition metals. The efficacy of SDG and particularly the mammalian lignans ED and EL to act as antioxidants in lipid and aqueous in vitro model systems, at relatively low concentrations (i.e. 100 microM), potentially achievable in vivo, is an evidence of a potential anticarcinogenic mechanism of flaxseed lignan SDG and its mammalian metabolites ED and EL.

4-Butyrolactone↗
PubMed2002

Short and stereoselective total synthesis of furano lignans (+/-)-dihydrosesamin, (+/-)-lariciresinol dimethyl ether, (+/-)-acuminatin methyl ether, (+/-)-sanshodiol methyl ether, (+/-)-lariciresinol, (+/-)-acuminatin, and (+/-)-lariciresinol monomethyl ether and furofuran lignans (+/-)-sesamin, (+/-)-eudesmin, (+/-)-piperitol methyl ether, (+/-)-pinoresinol, (+/-)-piperitol, and (+/-)-pinoresinol monomethyl ether by radical cyclization of epoxides using a transition-metal radical source.

Intramolecular radical cyclization of suitably substituted epoxy ethers 4a-g using bis(cyclopentadienyl)titanium(III) chloride as the radical source resulted in trisubstituted tetrahydrofurano lignans and 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans depending on the reaction conditions. The titanium(III) species was prepared in situ from commercially available titanocene dichloride and activated zinc dust in THF. Upon radical cyclization followed by acidic workup, epoxy olefinic ethers 4a-g afforded furano lignans dihydrosesamin 1a, lariciresinol dimethyl ether 1b, acuminatin methyl ether 1e, and sanshodiol methyl ether 1g directly and lariciresinol 1h, acuminatin 1i, and lariciresinol monomethyl ether 1j after removal of the benzyl protecting group by controlled hydrogenolysis of the corresponding cyclized products. The furofuran lignans sesamin 2a, eudesmin 2b, and piperitol methyl ether 2e were also prepared directly by using the same precursors 4a-f on radical cyclization followed by treatment with iodine and pinoresinol 2h, piperitol 2i, and pinoresinol monomethyl ether 2j after controlled hydrogenolysis of the benzyl protecting group of the corresponding cyclized products. Two naturally occurring acyclic lignans, secoisolariciresinol 5h and secoisolariciresinol dimethyl ether 5b, have also been prepared by exhaustive hydrogenolysis of 2h and 2b, respectively.

Alkylation↗
PubMedDate not supplied

A combined HPLC-UV and HPLC-MS method for the identification of lignans and its application to the lignans of Linum usitatissimum L. and L. bienne Mill.

A combined HPLC-UV/PAD and HPLC-ESI/MS method allowing the fast detection and identification/structural characterisation of lignans of different structural subclasses is described. Twenty-four lignans of different skeletal types were analysed and the combined information derived from their UV and ESI/MS spectra led to the identification of group characteristics that can be used to establish the structure of unknown lignans in plant samples. This method was successfully applied to the identification of lignans in crude extracts of Linum usitatissimum L. and L. bienne Mill.

Chromatography, High Pressure Liquid↗
PubMed2004

Urinary excretion of lignans after administration of isolated plant lignans to rats: the effect of single dose and ten-day exposures.

The difference in urinary excretion of mammalian and plant lignans in rats was determined after oral administration of equivalent doses (25 mg/kg of body weight) of 7-hydroxymatairesinol (HMR), lariciresinol (LAR), matairesinol (MR), and secoisolariciresinol (SECO). Twenty-four hours-urine samples were collected after a single dose and after administration of one dose/day for 10 days. Eight lignans were analysed in urine extracts using a high-performance liquid chromatography-tandem mass spectrometry method showing good sensitivity and repeatability. After a single dose of HMR, LAR, MR, and SECO, the main metabolites were 7-hydroxyenterolactone (HENL), cyclolariciresinol (CLAR), enterolactone (ENL), and enterodiol (END), respectively, but after 10-day exposure ENL was the main metabolite of all the tested lignans, showing a considerably higher excretion than after a single dose. Metabolic transformations of plant lignans into each other could also be observed.

Animals↗
PubMed2006

Schisandrene, a dibenzocyclooctadiene lignan from Schisandra chinensis: structure-antioxidant activity relationships of dibenzocyclooctadiene lignans.

Phytochemical investigation of the fruits of Schisandra chinensis led to the isolation of 13 lignans including schisandrene (13), a new lignan based on a dibenzocyclooctadiene backbone with an exocyclic double bond. Its structure and absolute configuration were established using NMR, MS, and CD data. Antioxidant activity of the lignans was evaluated using a DCFH-DA cellular-based assay. The structure-activity relationships of the dibenzocyclooctadiene lignans showed that the exocyclic methylene functionality was essential for antioxidant activity, with the benzoyloxy group probably enhancing such effects.

Antioxidants↗
PubMed2000

Justicia lignans VI--prostalidin D, a new arylnaphthalide lignan from Justicia diffusa var. prostrata C.B. Clarke.

A new arylnaphthalide lignan, prostalidin D (6) was isolated as a minor metabolite from Justicia diffusa var. prostrata. 6 contains a rare catechol unit and its structure was confirmed by total synthesis. In addition, seven known lignans, namely, justicidin E (7), helioxanthin (8), justicidin A (9), medioresinol dimethyl ether (10), medioresinol (11), lariciresinol (12) and 8-methoxyisolariciresinol (13) have also been isolated from the same source and identified by direct comparison with authentic samples.

India↗
PubMed1994

Studies on the preparation of bioactive lignans of oxidative coupling reaction. I. Preparation and lipid peroxidation inhibitory effect of benzofuran lignans related to schizotenuins.

The parent benzofuran lignan 4 of schizotenuins 1-3 and related compounds were efficiently prepared by a judicious use of the oxidative coupling reaction, and were tested for their inhibitory effects on lipid peroxidation in rat brain homogenate and rat liver microsomes. Among twelve compounds tested in rat brain homogenate, compounds 13, 14 and 16 showed prominent inhibitory activity. Compounds 13 and 16 were then tested in rat liver microsomes, and their activity was found to be more potent than schizotenuin A (1) and much more potent than that of (+/-)-alpha-tocopherol.

Animals↗
PubMed1994

Studies on the preparation of bioactive lignans by oxidative coupling reaction. II. Oxidative coupling reaction of methyl(E)-3-(4,5-dihydroxy-2-methoxyphenyl)propenoate and lipid peroxidation inhibitory effects of the produced lignans.

The oxidative coupling reaction of methyl (E)-3-4(4,5-dihydroxy-2-methoxyphenyl)propenoate (10), obtainable from esculetin, has been studied using silver oxide and potassium hexacyanoferrate(III). The products were separated, after acetylation, by silica gel column chromatography. 1-Aryl-1,2-dihydronaphthalene derivative 12 was obtained as a major product, accompanied by the benzo[kl]xanthene derivative 13. In the oxidation with silver oxide, a benzodioxane compound 14a was produced additionally in a minor amount. Thus, the course of the reaction differed notably from those of ferulic or caffeic acid derivatives. The compounds 11, 12, 13 and 14a were tested for their inhibitory effects on lipid peroxidation in rat brain homogenate and rat liver microsomes. They showed activities more effective than that of idebenone in rat brain homogenate, and were found to be more potent than benzofuran lignans 4 and 5, and much more potent than (+/-)-alpha-tocopherol in rat liver microsomes.

Animals↗
PubMed1993

Structural transformation of lignan compounds in rat gastrointestinal tract; II. Serum concentration of lignans and their metabolites.

Serum concentrations of arctiin, tracheloside, and their metabolites formed in the gastrointestinal tract were investigated in the rat. Arctiin or tracheloside was not detected in the serum after oral administration (200 mg/kg). In regard to their metabolites, each metabolite 1 (AM1, TM1), their genuine genins, appeared in the serum, and the serum concentration of arctiin metabolite 1 (AM1) reached its peak at 4 h and that of tracheloside metabolite 1 (TM1) reached its peak at 8 h. On the other hand, both metabolites 2 (AM2, TM2), which each possess a catechol moiety as reported previously, were not found in the serum. Now, we have studied the detection of their metabolites in the rat large intestinal contents after oral administration. It was revealed that all metabolites reported previously were certainly formed in rat gastrointestinal tract in vivo. Thus, we presumed a possibility that metabolite 2 was converted into metabolite 1 through C-3" methylation by catechol-O-methyltransferase (COMT) in rat liver. Each metabolite 2 was incubated with rat liver cytosol in the presence of S-adenosyl-L-methionine. It was proved that metabolite 2 was rapidly converted into metabolite 1 within 3 min. We suggest that arctiin or tracheloside was transformed to at least two metabolites in the gastrointestinal tract, and after absorption from the intestine, metabolite 2 was converted into metabolite 1 through methylation by COMT in the liver, and arctiin and tracheloside existed as metabolite 1, the genuine genin, in the blood stream.

4-Butyrolactone↗
PubMed1995

Studies on the preparation of bioactive lignans by oxidative coupling reaction. IV. Oxidative coupling reaction of methyl (E)-3-(3,4-dihydroxy-2-methoxyphenyl)propenoate and lipid peroxidation inhibitory effects of the produced lignans.

The oxidative coupling reaction of the hydroxycinnamate 11 derived from daphnetin has been investigated. The reaction with silver oxide afforded, after acetylation, a dihydrobenzofuran derivative 17 and a benzodioxane derivative 16a as major products accompanied with a small amount of a bis(benzylidene)succinate 18 and a dihydronaphthalene 19, while the oxidation with iron(III) chloride gave the dihydronaphthalene derivative 20 corresponding to 19. The reaction with potassium hexacyanoferrate(III) and Na2CO3 produced, after acetylation, 16a and 19 in lower yields. The propensity for product formation in the reaction of 11 is discussed in relation to data for the reactions of hydroxycinnamate derivatives studied so far. The obtained compounds were tested for inhibitory effects on lipid peroxidation in rat brain homogenate and rat liver microsomes. In the rat brain homogenate the five compounds showed inhibitory activity more potent than that of idebenone. Compounds 17 and 20 were then tested in rat liver microsomes, and found to be more potent than schizotenuin A and much more potent than (+/-)-alpha-tocopherol.

Animals↗
PubMed1995

Studies on the preparation of bioactive lignans by oxidative coupling reaction. V. Oxidative coupling reaction of methyl (E)-3-(2-hydroxyphenyl)propenoate derivatives and lipid peroxidation inhibitory effects of the produced lignans.

The oxidative coupling reactions of 2-hydroxycinnamates were investigated as a continuation of our previous studies on 4-hydroxy derivatives. The reaction of 2-hydroxycinnamate 1 and 2-hydroxy-4-methoxycinnamate 3 with silver oxide afforded polymerized lignin-like products, while that of 2-hydroxy-bis(methoxymethoxy)cinnamates 5 and 6, after acetylation, gave the enol acetates, 8 and 14, of oxotetrahydrobenzoxanthene derivatives, respectively. These two products were also obtained by the oxidation of 5 and 6 with potassium hexacyanoferrate(III). In the reactions of 5 and 6 with iron(III) chloride, the major products were the partially demethoxymethoxylated compounds 9 and 15, respectively. Thus, the course of the reactions in the oxidation of 2-hydroxycinnamates is quite different from that in the case of 4-hydroxy derivatives. The product 8 and the corresponding oxotetrahydrobenzoxanthene derivative were found to show moderate inhibitory effects upon lipid peroxidation.

Animals↗