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.     

Eusiderins and other neolignans from an Aniba species

A previous report disclosed the presence of benzodioxan and bicyclo[3.2.1]octanoid neolignans in the benzene extract of the trunk wood of an Amazonian Aniba (Lauraceae) species. The chloroform extract of the same material contains additionally two new benzodioxan neolignans [rel-(7S,8R)-Δ^8′-7-hydroxy-3,4,5,5′-tetramethoxy-7.0.3′,8.0.4′-neolignan; rel-(7R,8R)-Δ^7′-3,4,5,5′-tetramethoxy-9′-oxo-7.0.3′,8.0.4′-neolignan], two new bicyclo[3.2.1]-octanoid neolignans [(7R,8S,1′S,2′S,3′S,4′R)-Δ^8′-2′,4′-dihydroxy-3,3′-dimethoxy-4,5-methylenedioxy-1′,2′,3′,4′,5′,6′-hexahydro-5′-oxo-7.3′,8.1′-neolignan; (7R,8S,1′R,2′S,3′S)-Δ^8′-2′-hydroxy-3,3′,5′-trimethoxy-4,5-methylenedioxy-1′,2′,3′,4′-tetrahydro-4′-oxo-7.3′,8.1′-neolignan] and a hydrobenzofuranoid neolignan [(7S,8R,1′S,5′S)-Δ^8′-3,3′,5′-tri-methoxy-4,5-methylenedioxy-1′,4′,5′,6′-tetrahydro-4′-oxo-7.0.2′,8.1-neolignan].     

Neolignans from Aniba ferrea

The trunk wood of the Amazonian Aniba ferra Kubitzki contains, besides three benzyl benzoates (1a, b, c) and dillapiol (2), four hydrobenzofuranoid and two bicyclo [3.2.1] octanoid neolignans. The former comprise two representatives (3a, b) of the novel ferrearin- (3a-allyl-2- aryl-7a-hydroxy-3-methyl-3a,4,7,7a-tetrahydro-7-oxobenzofuran type, and two further representatives (4a, b) of the known porosin-(3a-allyl-2-aryl-5-methoxy-3a,4,5,6-tetrahydro-6-oxobenzofuran) type. The latter comprises a new representative (5a) of the known canellin- (1-allyl-6-aryl-7-methylbicyclo [3.2.1] octane) type, and the methyl ether (6a) of a known guianin- (1-allyl-6-aryl-7-methyl-4-oxobicyclo [3.2.1] oct-2-en) type neolignan.     

Neolignans from Ocotea aciphylla

The trunk wood of the central Brazilian Ocotea aciphylla contains two hydrobenzofuranoid and three bicyclo[3.2.1]octanoid neolignans. The former comprise a novel representative of the rare ferrearin (3a-allyl-2-aryl-7a-hydroxy-3-methyl-2,3,3a,4,7,7a-hexahydro-7-oxobenzofuran) type.     

Neolignans from an Aniba species

The trunk wood of an Amazonian Aniba (Lauraceae) species contains, besides dillapiol and the benzodioxane-type neolignan eusiderin, four bicyclo(3.2.1)octanoid neolignans. These comprise representatives of the canellin-type: the known methoxycanellin-A and the novel compounds characterized as (1R, 3S, 4S, 5S, 6S, 7R)-1-allyl-4-hydroxy-3, 5-dimethoxy-7-methyl-6-(3′-methoxy-4′, 5′-methylenedioxyphenyl)-8-oxo-bicyclo(3.2.1)octane; (1R, 3S, 4S, 5S, 6S, 7R)-1-allyl-4-hydroxy-3, 5-dimethoxy-7-methyl-6-(3′, 4′, 5′-trimethoxyphenyl)-8-oxobicyclo(3.2.1)octane and (1R, 4R, 5R, 6S, 7R, 8S)-1-allyl-4, 8-dihydroxy-5-methoxy-7-methyl-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-3-oxobicyclo(3.2.1)octane.     

Neolignans from an Aniba species

A benzene extract of the trunk of an Aniba species (Lauraceae) contained benzyl benzoate, benzyl salicylate, sitosterol and the neolignans (2S,3S,3aR)-3a-allyl-5-methoxy-3-methyl-2-piperonyl-2,3,3a,6-tetrahydro-6-oxobenzofuran (burchellin); (2S,3S,3aR)-3a-allyl-5-methoxy-3-methyl-2-veratryl-2,3,3a,6-tetrahydro-6-oxobenzofuran; (2S,3S,3aR)-3a-allyl-5,7-dimethoxy-3-methyl-2-veratryl-2,3,3a,6-tetrahydro-6-oxobenzofuran; (2S,3S,5S)-5-allyl-5-methoxy-3-methyl-2-veratryl-2,3,5,6-tetrahydro-6-oxo-benzofuran; (2R,3R)-7-methoxy-3-methyl-5-propenyl-2-veratryl-2,3-dihydrobenzofuran; rel-(1R,5R,6R,7R,8S)-1-allyl-8-hydroxy-3-methoxy-7-methyl-4-oxo-6-piperonylbicyclo[3,2,1]oct-2-ene (guianin); rel-(1S,5S,6S,7R,8R)-1-allyl-8-hydroxy-3,5-dimethoxy-7-methyl-4-oxo-6-piperonylbicyclo[3,2,1]oct-2-ene; rel-(1S,5S,6S,7R,8R)-8-acetoxy-1-allyl-3-hydroxy-5-methoxy-7-methyl-4-oxo-6-piperonyl-bicyclo[3,2,1]oct-2-ene; rel-1S,5S,6S,7R,8R)-8-acetoxy-3,5-dimethoxy-7-methyl-4-oxo-6-piperonylbicyclo[3,2,1]oct-2-ene; rel-(1R,5S,6R,7R)-1-allyl-3-methoxy-7-methyl-4,8-dioxo-6-piperonylbicyclo[3,2,1]oct-2-ene.     

Lignans and neolignans from Licaria armeniaca

A re-examination of the trunk wood of Licaria armeniaca led to the isolation of 6,7-dimethoxycoumarin, 1,2,3-trimethoxy-7-oxoaporphine (tri-O-methylmoschatoline, 2e-(3,4,5-trimethoxyphenyl)-6e-(3,4-dimethoxyphenyl)-3,7-dioxabicyclo [3.3.0]octan (magnolin) and a novel neolignan (7S,8R,1′S,2′S,3′S)-2′-acetoxy-1′-allyl-3′,5′-dimethoxy-8-methyl-7-piperonyl-bicyclo [3.2.1]-oct-5′- en-4′-one.     

Neolignans from Ocotea catharinensis

Bark, wood and leaves of Ocotea catharinensis contain respectively 10 (average yield 0.7%.), 15 (average yield 0.004%.) and one (yield 0.4%.) neolignans of the bicyclo[3.2.1]octanoid and the hydrobenzofuranoid structural types, including the new rel-(7S,8R,1′R,4′S,5′R,6′R)-Δ^8′-4′,6′-dihydroxy-5′-methoxy-3,4-methylenedioxy-3′-oxo-8.1′,7.5′-neolignan, (7S,8S)-Δ^{1′,3′,5′,8′}-5,3′,5′-trimethoxy-3,4-methylenedioxy-8.1′,7.O.6′,4.O.7′-neolignan, (7R,8S,1′R,3′R)-Δ^5′,8′-3,4,3′,5′-tetramethoxy-4′-oxo-8.1′,7.O.6′-neolignan and rel-(7R,8S,1′R,2′S)-Δ^4′,8′-2′-hydroxy-3,4-dimethoxy-3′-oxo-8.1′,7.O.2′-neolignan.     

Benzofuranoid neolignans from Aniba simulans

Forteen neolignans, isolated from the benzene extract of Aniba simulans (Lauraceae) trunk wood, included the hitherto undescribed (2S, 3S, 5R)-5-allyl-5,7-dimethoxy-2-(3′,4′,5′-trimethoxyphenyl)-3-methyl-2,3,5,6-tetra-hydro-6-oxobenzofuran, (2R,3S,5R) -5-allyl-5-methoxy-2-(3′-methoxy-4′,5′-methylenedioxyphenyl)-3-methy1-2,3,5, 6-tetrahydro-6-oxobenzofuran, (2S,3S)-6-O-allyl -5-methoxy-2-(3′-methoxy-4′-5′-methylenedioxyphenyl)-3-methyl-2,3-dihydrobenzofuran, (2R,3S)-6-O-allyl-5-methoxy-2- (3′-methoxy-4′,5′-methylenedioxyphenyl)-3-methyl-2,3-dihydrobenzofuran and 7-allyl-6-hydroxy-5-methoxy-2-(3′-methoxy-4,5′ -methylenedioxyphenyl)-3-methylbenzofuran.     

Hexahydrobenzofuranoid neolignans from an Aniba species

The trunk wood of an Amazonian Aniba species contains three novel neolignans: (2R, 3R, 3aS, 5R)-3a-allyl-5-methoxy-2-(3,4,5-trimethoxyphenyl)-3-methyl-2,3,3a,4,5,6-hexahydro-6-oxobenzofuran (canellin-D), (2R,3R,3aS,5R)-3a-allyl-5,7-dimethoxy-2-(3-methoxy-4,5-methylenedioxyphenyl)-3-methyl-2,3,3a,4,5,6-hexahydro-6-oxobenzofuran (canellin-E) and (2S,3S,3aS,5R)-3a-allyl-5-methoxy-2-(3-methoxy-4,5-methylenedioxyphenyl)-3-methyl-2,3,3a,4,5,6-hexahydro-6-oxobenzofuran (armenin-C). The absolute stereochemistries of these and of all other known hexahydro-6-oxobenzofurans were determined by CD comparisons with model compounds.     

PAF-antagonistic bicyclo[3.2.1]octanoid neolignans from leaves of Ocotea macrophylla Kunth. (Lauraceae)

Di-nor-benzofuran neolignan aldehydes, Δ⁷-3,4-methylenedioxy-3′-methoxy-8′,9′-dinor-4′,7-epoxy-8,3′-neolignan-7′-aldehyde (ocophyllal A) 1, Δ⁷-3,4,5,3′-tetramethoxy-8′,9′-dinor-4′,7-epoxy-8,3′-neolignan-7′-aldehyde (ocophyllal B) 2, and macrophyllin-type bicyclo[3.2.1]octanoid neolignans (7R, 8R, 3′S, 4′S, 5′R)-Δ⁸′-4′-hydroxy-5′-methoxy-3,4-methylenedioxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan (ocophyllol A) 3, (7R, 8R, 3′S, 4′S, 5′R)-Δ⁸′-4′-hydroxy-3,4,5′-trimethoxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan (ocophyllol B) 4, (7R, 8R, 3′S, 4′S, 5′R)-Δ⁸′-4′-hydroxy-3,4,5,5′-tetramethoxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan (ocophyllol C) 5, as well as 2′-epi-guianin 6 and (+)-licarin B 7, were isolated and characterized from leaves of Ocotea macrophylla (Lauraceae). The structures and configuration of these compounds were determined by extensive spectroscopic analyses. Inhibition of platelet activating factor (PAF)-induced aggregation of rabbit platelets were tested with neolignans 1–7. Although compound 6 was the most potent PAF-antagonist, compounds 3–5 showed some activity.     

Neolignans from Ocotea catharinensis

The trunk bark of Ocotea catharinensis yielded, besides the known bicyclo(3.2.1)octanoid neolignans canellin-C and 5′-methoxycanellin-C, two epimers rel-(1R,4S and 4R,5S,6R,7S,8R)-1-allyl-4,8-dihydroxy-3,5-dimethoxy-7-methyl-6-piperonyl-bicyclo(3.2.1)oct-2-enes and rel-(1R,5S,6R,7S,8R)-1-allyl-3,8-dihydroxy-5-methoxy-7-methyl-6-piperonyl-4-oxobicyclo(3.2.1)oct-2-ene. The hydrobenzofuranoid neolignans are represented by the equally novel (2S,3S,5R)-5-allyl-5,7-dimethoxy-3-methyl-2-piperonyl-2,3,5,6-tetrahydro-6-oxobenzofuran and (2R,3S,3aS)-3a-allyl-5,7-dimethoxy-3-methyl-2-piperonyl-2,3,3a,6-tetrahydro-6-oxobenzofuran.     

Neolignans from Aniba citrifolia

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

Neolignans from Aniba terminalis

A benzene extract of the trunk wood of Aniba terminalis (Lauraceae) contained besides benzyl benzoate, benzyl salicylate, d,1-camphor and sitosterol, (2S,3S,3aR)- and (2R,3S,3aS)-3a-allyl-5-methoxy-3-methyl-2-piperonyl-2,3,3a,6-tetrahydro-6-oxobenzofurans, which may be responsible, through sequential rearrangements of the Cope, retro-Claisen and Claisen types, and finally dehydrogenation, for the formation of the co-occurring (2S,3S,5S)- and (2R,3S,5R)-5-allyl-5-methoxy-3-methyl-2-piperonyl-2,3,5,6-tetrahydro-6-oxobenzofurans, the (2S,3S)-6-O-allyl-5-methoxy-3-methyl-2-piperonyl-2,3-dihydrobenzofuran, the (2S,3S)- and (2R,3S)-7-allyl-6-hydroxy-5-methoxy-3-methyl-2-piperonyl-2,3-dihydrobenzofuran and the 7-allyl-6-hydroxy-5-methoxy-3-methyl-2-piperonylbenzofuran.     

Neolignans from a Nectandra species

The trunk wood of an Amazonian Nectandra (Lauraceae) species contains one bicyclo[3.2.1]octanoid and four hydrobenzofuranoid neolignans. The latter comprise representatives of the mirandin, the rearranged burchellin and the burchellin types. The former was characterized as (1S, 4R, 5S, 6R, 7R)-3-allyl-4-hydroxy-1-methoxy-(3′, 4′, 5′-trimethoxyphenyl)- 7-methyl-8-oxobicyclo[3.2.1]oct-2-ene macrophyllin-B), a new representative of the seemingly rare macrophyllin type.     

Guianin: A neolignan from Aniba guianensis

The wood of Aniba guianensis Aubl. (Lauraceae) contains benzyl benzoate, benzyl salicylate, sitosterol, O-methyleugenol, O-methylisoeugenol and the neolignan guianin for which the structure of 1-allyl-8-hydroxy-3-methoxy-7-methyl-4-oxo-6-piperonylbicyclo[3,2,1]oct-2-ene (VI) is proposed.     

The neolignans of Licaria canella

The trunk wood of Licaria canella contains, besides dillapiol and elemicin, the neolignans canellin-A, -B and -C, for which the respective structures of 1-allyl-4,8-dihydroxy-3,5-dimethoxy-7-methyl-6-piperonylbicyclo-[3,2,1]octane; 3a-allyl-4,5-dimethoxy-3-methyl-2-piperonyl-2,3,3a,6,7,7a-hexahydro-6-oxobenzofuran and 1-allyl-4,8-dihydroxy-5-methoxy-7-methyl-6-piperonyl-3-oxobicyclo-[3,2,1] octane are proposed.     

Neolignans from Aniba lancifolia

The branches of the shrub Aniba lancifolia Kubitzki et Rodrigues (Lauraceae) contain besides 2-hydroxy-4,5- dimethoxyallylbenzene and its dimer cyclohexan-2-allyl- 5-en-4,5-dimethoxy-4-O-(2′-allyl-4′,5′-dimethoxyphenyl)-1-one (lancilin, 2) 6 further novel neolignans: (4S,2′R)- and (4R,2′E)-cyclohexan-2-allyl-2,5-dien-4,5-dimethoxy-4-[2′-(1′-guaiacyl)-propyl]-1-one (lancifolins A and B, 3a and 3b), (4S,2′R)- and (4R,2′R)-cyclohexan- 2-allyl-2,5-dien-4,5-dimethoxy-4-[2′-(1′-veratryl)-propyl]-1-one (lancifolins C and D, 3c and 3d), (4S,2′R)-and (4R,2′R)-cyclohexan-2-allyl-2,5-dien-4,5-dimethoxy-4-[2′-(1′-piperonyl)-propyl]-1-one (lancifolins E and F, 3e and 3f).     

An unusual porosin type neolignan from Licaria chrysophylla

The trunk wood of Licaria chrysophylla contains rel-(7S, 8R, 1′S, 5′S)-Δ^8′-3,3′,5′-trimethoxy-4,5-methylenedioxy-1′,4′,5′,6′- tetrahydro-4′-oxo-7.1′,8.0.2′-neolignan (chrysophyllin A), which differs from all other known benzofuranoid neolignans by showing 7.1′ (rather than 8.1′) and 8.0.2′ (rather than 7.0.2′) linkages between the propenylphenol and allylphenol derived moieties.