Neolignans from Magnolia denudata

New neolignans, denudatin A and B (hydrobenzofuranoids) and denudatone [spiro(5,5)undecanoid], together with three known neolignans including burchelli     

Neolignans from the seeds of Prunus tomentosa (Rosaceae) and their chemotaxonomic interest

The role of neolignans in the chemotaxonomy of the genus Prunus has long been neglected. In this study, two new dihydrobenzofuran neolignans tomentosanans A (12) and B (14), together with 15 known neolignans, were isolated from the seeds of Prunus tomentosa. This is the first report on the occurrence of compounds 1–12, 14, 15 and 17 in the genus Prunus. The biosynthetic pathways of these neolignans are also summarized. Together, these neolignans represent a phytochemical fingerprint for P. tomentosa, which may be used for identification of Prunus species.     

Chemosystematics of Aniba

A taxonomic subdivision of the genus Aniba (Lauraceae) which comprises 41 recognized species is, for the major part, compatible with a chemical subdivision of the genus which can be made on the basis of the mutually exclusive presence of neolignans vs benzophenones, pyrones and flavonoids. While the presence of neolignans is considered a primitive character of the genus Aniba, the occurrence of pyrones and biosynthetically related compounds is regarded as an advanced character. The chemistry of two closely allied species, of which one produces neolignans, the other pyrones plus an allylphenol, gives a clue for the understanding of the chemical evolution within this genus, for which a unified biosynthetic scheme is presented.     

Neolignans from Virola carinata fruit

The fruits of Virola carinata contain the lignans (?)-cubebin, (?)-hinokinin and (+)-asarinin, besides four neolignans of the β-aryloxy-arylpropane type and two neolignans of the benzodioxane (eusiderin) type.     

Aryltetralone and arylindanone neolignans from Virola sebifera

The fruits of Virola sebifera contain several tetralone neolignans, including 2,4-dihydroxy-6,7-methylenedioxy-2,3-dimethyl-4-veratryltetralin-1-one. The 3-hydroxylated derivative of this compound may undergo a biosynthetic pinacol-pinacolone rearrangement to give 2-acetyl-3-hydroxy-2-methyl-5,6-methylenedioxy-3-veratrylindan-1-one which, together with other indanone neolignans, was also isolated.     

The first record of neolignans from the marine phanerogam Posidonia oceanica

Chemical analysis of the secondary metabolites of Posidonia oceanica rhizomes led to the identification of several compounds. In particular, two neolignans, co-occurring with related metabolites previously described from the plant kingdom, have been isolated and characterised by spectroscopic methods. To the best of our knowledge, this is the first report of neolignans from a marine phanerogam.     

COX,LOX and platelet aggregation inhibitory properties of Lauraceae neolignans

The anti-inflammatory potential of 26 neolignans (14 of the bicyclooctane-type and 12 of the benzofuran-type), isolated from three Lauraceae species (Pleurothyrium cinereum, Ocotea macrophylla and Nectandra amazonum), was evaluated in vitro through inhibition of COX-1, COX-2, 5-LOX and agonist-induced aggregation of rabbit platelets. Benzofuran neolignans were found to be selective COX-2 inhibitors, whereas bicyclooctane neolignans inhibit selectively the PAF-action as well as COX-1 and 5-LOX. The neolignan 9-nor-7,8-dehydro-isolicarin B 15 and cinerin C 7 were found to be the most potent COX-2 inhibitor and PAF-antagonist, respectively. Nectamazin C 10 exhibited dual 5-LOX/COX-2 inhibition.     

Benzofuranoid Neolignans from Piper kadsura

In a continuing research for neolignans from Piper kadsura (Choisy) Ohwi, six benzofuranoid neolignans were isolated from the aerial part of the plant. Their structure determination were based on the spectroscopic analysis (UV, IR, MS, NMR and CD) and derivative synthesis. Three of the isolated compounds were identified as new structures: 7R, 8R, 1′S-△8′-3, 4-methylenedioxy-5′-methoxy-l′, 4′-dihydro-4′-oxo-7, 0, 2′, 8. l′-neolignan ( Ⅰ ), 7 R, 8 R, 1 ′ R- △8′ - 3,4- methylenedioxy- 1 ′- methoxy - 1′,6′- dihydro- 6′- oxo- 7.0.4′,8. 3′-neolignan (Ⅳ) and 7R, 8R, 1′S-△8′-3, 4-methylenedioxy-l′-methoxy-1′,6′-dihydro-6′-oxo-7.0.4′,8.3′-neolignan (Ⅴ). Known compounds among them are 7R, 8S,1′S-△8′-3, 4-methylenedioxy-5′-methoxy-1′, 4′-dihydro-4′-oxo-7. 0. 2′, 8. 1′-neolignan(Ⅱ), 7S, 8S, 1′R-△8′-3, 4, 5′-trimethoxy-1′, 4′-dihydro-4′-oxo-7.0. 2′, 8. 1′-neolignan (Ⅲ) and 75, 85, 1′S-△8′-3, 4, l′-trimethoxy-l′, 6′-dihydro-6′-oxo-7. 0. 4′, 8. 3′-neolignans (Ⅵ). All of them were isolated from the plant for the first time.     

Neolignans from Urbanodendron verrucosum

Branch wood of the shrub Urbanodendron verrucosum from the Atlantic forest of southern Brazil contains the benzofuranoid neolignans licarin-A, licarin-D, porosin and the novel porosin-B, as well as the tetrahydrofurane neolignans austrobailignan-7, calopiptin and the novel verrucosin. The acid-catalysed rearrangement of the porosins yields the corresponding dihydrofutoenones.     

Amenyunnaosides A–C,Three New Neolignans Isolated from Amentotaxus yunnanensis and Their Anti-inflammatory Activities

Phytochemical study on the leaves of Amentotaxus yunnanensis led to the isolation of seventeen phenolic compounds including sixteen neolignans and lignans, and one flavone glycoside. Three among the isolates were previously unreported neolignans and named as amenyunnaosides A–C, respectively. Their structures were elucidated by extensive analyses of HR-ESI-MS, 1D and 2D NMR, and ECD spectra. The isolated neolignans potentially inhibited NO production in LPS-activated RAW264.7 cells with their IC₅₀ values ranging from 11.05 to 44.07 μM, compared to that of the positive control compound, dexamethasone, IC₅₀ value of 16.93 μM. Additionally, amenyunnaoside A dose-dependently reduced production of IL-6 and COX-2 but did not effect to that of TNF-α at concentrations of 0.8, 4, and 20 μM.     

Seed-coat protective neolignans are produced by the dirigent protein AtDP1 and the laccase AtLAC5 in Arabidopsis

Lignans/neolignans are generally synthesized from coniferyl alcohol (CA) in the cinnamate/monolignol pathway by oxidation to generate the corresponding radicals with subsequent stereoselective dimerization aided by dirigent proteins (DIRs). Genes encoding oxidases and DIRs for neolignan biosynthesis have not been identified previously. In Arabidopsis thaliana, the DIR AtDP1/AtDIR12 plays an essential role in the 8-O-4′ coupling in neolignan biosynthesis by unequivocal structural determination of the compound missing in the atdp1 mutant as a sinapoylcholine (SC)-conjugated neolignan, erythro-3-{4-[2-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-1-hydroxymethylethoxy]-3,5-dimethoxyphenyl}acryloylcholine. Phylogenetic analyses showed that AtDP1/AtDIR12 belongs to the DIR-a subfamily composed of DIRs for 8-8′ coupling of monolignol radicals. AtDP1/AtDIR12 is specifically expressed in outer integument 1 cells in developing seeds. As a putative oxidase for neolignan biosynthesis, we focused on AtLAC5, a laccase gene coexpressed with AtDP1/AtDIR12. In lac5 mutants, the abundance of feruloylcholine (FC)-conjugated neolignans decreased to a level comparable to those in the atdp1 mutant. In addition, SC/FC-conjugated neolignans were missing in the seeds of mutants defective in SCT/SCPL19, an enzyme that synthesizes SC. These results strongly suggest that AtDP1/AtDIR12 and AtLAC5 are involved in neolignan biosynthesis via SC/FC. A tetrazolium penetration assay showed that seed coat permeability increased in atdp1 mutants, suggesting a protective role of neolignans in A. thaliana seeds.

The dirigent protein AtDP1/AtDIR12 and the laccase AtLAC5 play essential roles in the biosynthesis of seed-coat protective neolignans via sinapoylcholine/feruloylcholine in Arabidopsis.     

Improving the efficiency of wheat microspore culture methodology: evaluation of pretreatments,gradients, and epigenetic chemicals

Plant Cell, Tissue and Organ Culture (PCTOC) - Cell suspension culture of Linum usitatissimum is a great source of the novel and multipurpose medicinal compounds lignans and neolignans....     

Chemical dichotomies in the Magnolialean complex

The most characteristic chemosystematic feature of the Magnolialean families (here delineated to include the Magnoliiflorae plus Piperales in the sense of Dahlgren, 1983) is the rich diversification of two groups of secondary metabolities, the neolignans and benzylisoquinolines. From a survey of their distribution it becomes apparent that several shifts have led to the predominance of one of these two groups or their mutual exclusion in these families. Biogenetic considerations and correlation with morphological advancement suggest the evolutionary primacy of neolignans over benzylisoquinolines, but it is assumed that the capacity to produce both groups of substances must be very old. Apparently the presumed loss of benzylisoquinolines in various small families such as the Himantandraceae and Calycanthaceae has triggered the evolution of novel classes of compounds in compensation. Chemical changes leading to dissimilarities between sister groups as described in this paper may camouflage natural relationships.     

Guaiane sesquiterpenes from Magnolia watsonii

The leaves and the trunk barks of Magnolia watsonii afforded two biosynthetic intermediates of dehydrocostuslactone (watsonol A and watsonol B) along with the neolignans, magnolol, hōnokiol and obovatol, and the aporphine alkaloids, liriodenine and asimilobine.     

Structural confirmation of neolignans

The proposed structures of the neolignans canellin-A, macrophyllin-B and eusiderin were confirmed by X-ray crystallographic analyses.     

Absolute configuration of the benzofuranoid neolignans

The benzofuranoid neolignans, classified into structurally homogeneous groups by constitution and ORD curves, have had their relative configurations es     

Neolignans from Licaria rigida

Trunk wood of Licaria rigida contains the neolignans eusiderin, eusiderin-B, canellin-A and canellin-C.     

苯骈呋喃类和双环[3,2,1]辛烷类新木脂素的合成进展

本文对苯骈呋喃类和双环「３,２,１」辛烷类新木脂素的合成进行了综述。     

Neolignans from Aniba citrifolia

The trunk wood of Aniba citrifolia contains hydrobenzofuranoid and bicyclo[3.2.1]octanoid neolignans.     

Hermosillol,an 8,3′-neolignan from Krameria sonorae

The aerial parts of Krameria sonorae afforded seven known neolignans and nor-neolignans, and as a major component, a new 8,3′-neolignan which was named hermosillol.