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.     

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.     

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.     

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.     

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 of Virola surinamensis

Elemicin, galbacin, veraguensin and two new neolignans, surinamensin and virolin, were isolated and characterized from the leaves of Virola surinamensis.     

Phytochemical analysis of the hot tea infusion of Hedyosmum brasiliense

The leaves of the neotropical dioecious shrub Hedyosmum brasiliense (HB) are employed popularly as a sedative, aphrodisiac and as a substitute for green tea.The aim of this work was to study the composition of the hot tea infusion from the fresh leaves of HB, comparing its androecious or gynoecious parts, including the isolation and identification of new secondary metabolites. The characterization of the HB tea infusion was achieved by means of UHPLC–ESI(±)-HRMS and the isolation of its secondary metabolites was done through FCPC and MPLC. Both female and male plant extracts presented similar chemical profiles, with rosmarinic acid (RA) as the main compound. The FCPC analysis led to a one-step isolation of RA 97% pure. A new sesquiterpene lactone (1-α-acetoxyeudesma-3,7(11)–dien–8,12–olide) is reported herein for the first time. The additional compounds isolated and characterized by NMR and LC–MS are isorinic acid, a glycosylated flavonol, two neolignans reported for the first time for HB and three other sesquiterpene lactones which were previously isolated from the ethanol extract. Neither the extract nor its major constituent (RA) exhibited in-vitro antimycobacterial activity.     

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.     

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.     

Neolignans of Virola carinata bark

Four neolignans, dehydrodieugenol, its monomethylether, carinatone and carinatin have been isolated from the hexane fraction of the bark of Virola carinata. Three new neolignans were separated from the chloroform fraction and examined by spectroscopy and chemical reactions. Their structures were determined as (2S, 3S)-5-allyl- 7-methoxy-3-hydroxymethyl-2-(3′,4′-dimethoxyphenyl)-2,3-dihydrobenzofuran, (2S)- 1-(3′,4′-dimethoxyphenyl)-2-(3″-allyl-5″-methoxy-6″-hydroxyphenyl)propanone(1) ol(3), (1S,2S)-1-(3′,4′-dimethoxyphenyl)-2-(3″-allyl-5″-methoxy-6″-hydroxyphenyl) propanol(1) and called dihydrocarinatinol, carinatonol and carinatol, respectively.     

Neolignans from Piper futokadsura

The structures of three new neolignans, kadsurenone, kadsurin A and kadsurin B, isolated from Piper futokadsura were determined by chemical and spectral analysis and X-ray diffraction study. Their biological activities are reported.     

Cytotoxic dihydrobenzofuran neolignans from Mappianthus iodoies

Three new dihydrobenzofuran neolignans, mappiodoinins A-C (1-3), together with nine known analogues (4 -12) were isolated from the stems and leaves of Mappianthus iodoies. Their structures with the absolute configurations were elucidated by extensive spectroscopic methods. This is the first time to find dihydrobenzofuran neolignans from the genus Mappianthus. All isolated compounds were evaluated for their cytotoxicities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW-480 in vitro. Neolignans 1-12 showed significant cytotoxic effects against various human cancer cell lines with IC₅₀ values ranging from 0.16 to 18.62 μM.     

Neolignans from Licaria rigida

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

Neolignans from Aniba citrifolia

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

Neolignans from Aniba burchellii

Seven neolignans, isolated from the benzene extract of Aniba burchellii Kosterm. (Lauraceae), included the hitherto unknown (2S,3S,5S)-5-allyl-5-methoxy-3-methyl-2-(3′,4′-methylenedioxyphenyl)-2,3,5,6-tetrahydro-6-oxobenzofuran and (1R,5R,6R,7R)-1-allyl-6-(4′-hydroxy-3′-methoxyphenyl)-3-methoxy-7-methyl-4,8-dioxobicyclo-[3,2,1]oct-2-ene. The former structure was previously assigned to a constituent of A. terminalis Ducke which is in fact the 5R-epimer. In addition to the latter constituent, all other previously described 4-oxobicyclo[3,2,1]oct-2-ene neolignans had their absolute configuration established.     

Further lignoids from Virola sebifera

From the fruits of Virola sebifera 2,3-dibenzylbutanes were isolated together with tetralin and naphthalene neolignans. 2,3-Dimethyl-4-piperonyl-4-veratrylbutan-1-ol, a further constituent, probably arises by a retro-Friedel-Crafts reaction from a tetralin neolignan. An additional component was identified as a dimeric neolignan.     

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.     

Lignans neolignans and norneolignans from krameria cystisoides

The hexane extract from the roots of Krameria cystisoides yielded besides conocarpan, licarin A, eupomatenoids 6 and 13, and ratanhiaphenol I 16 hitherto unknown lignans, neolignans and nomeolignans, among them toltecol and olmecol. Structural elucidation was based mainly on spectroscopic investigations, especially ¹³CNMR.     

Neolignans from fruits of Virola elongata

Fruits of Virola elongata contain, besides the furofuranoid lignans eudesmin, epieudesmin and fargesin, the aryl-benzyl-methyl tetrahydrofuran neolignans magnostellins A and C. The absolute configuration of the magnostellins was detennined.     

Lignans and neolignans from Buddleja davidii

A methanolic extract of Buddleja davidii stem yielded the known compounds coniferaldehyde, balanophonin and syringaresinol, and six novel compounds which were characterized as arylglycerol-substituted lignans and neolignans. These have been named buddlenols A-F.