Neolignans from stem bark of ocotea veraguensis

The stem bark of Ocotea veraguensis has yielded nine neolignans of which five appear to be novel. The new neolignans, which were identified on the basis of spectral characteristics, are^* (7S,8R,1′S,2′S,3′R,4′S)-Δ^8′-2′,4′-dihydroxy-3,3′5′-trimethoxy-4,5-methylenedioxy-1′,2′,3′,4′-tetrahydro-7.3′,8.1′-neolignan, (7S,8R,1′S,3′S,4′S)-Δ^8′-4,4'-dihydroxy-3,3′,5′-trimethoxy-1′,2′,3′,4′-tetrahydro-2′-oxo-7.3′,8.1′-neolignan, (7S,8S,1′R)-Δ^8′-3′,5′-dimethoxy-3,4-methylenedioxy-1′,4′-dihydro-4′-oxo-7.0.2′,8.1′-neolignan, (7S,8S,1′R )-Δ^8′-1′-methoxy-3,4-methylenedioxy-1′,6′-dihydro-6′-oxo-7.0.4′,8.3′-neolignan and (7S,8S)-Δ^8′-2′,6′-dimethoxy-3,4-methylenedioxy-7.0.3′,8.4′,1′.0.7′-neolignan.     

Dilignol glycosides from needles of Picea abies

(2R,3R)-2 3-Dihydro-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-5-benzofuranpropanol 4′-O-β-d-glucopyranoside [dihydrodehydrodiconiferyl alcohol glucoside], (2R,3R)-2 3-dihydro-7-hydroxy-2-(4′-hydroxy-3′-methoxyphenyl)-3-(hydroxymethyl)-5-benzofuranpropanol 4′-O-β-d-glucopyranoside and 4′-O-α-l-rhamnopyranoside, 1-(4′-hydroxy-3′-methoxyphenyl)-2- [2″-hydroxy-4″-(3-hydroxypropyl)phenoxy]-1, 3-propanediol 1-O-β-d-glucopyranoside and 4′-O-β-d-xylopyranoside, 2,3-bis[(4′-hydroxy-3′-methoxyphenyl)-methyl]-1,4-butanediol 1-O-β-d-glucopyranoside [(?)-seco-isolariciresinol glucoside] and (1R,2S,3S)-1,2,3,4-tetrahydro-7-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl)-6-methoxy-2 3-naphthalenedimethanol α²-O-β-d-xylopyranoside [(?)-isolariciresinol xyloside] have been isolated from needles of Picea abies and identified.     

New coumarins from Coleonema album

Six coumarins have been isolated from the aerial parts of Coleonema album and identified as ulopterol, 7-(3′, 3′-dimethylallyloxy)-coumarin, (R)-(+)-2′,3′-epoxy-suberosin, and the novel coumarins (R)-(+)-7-(2′, 3′-epoxy-3′-methylbutoxy)-coumarin, (R)-(+)-7-(2′,3′-dihydroxy-3′-dihydroxy-3′-methylbutoxy)-coumarin and (R)-(+)-7-methoxy-8-(2′,3′-epoxy-3′-methylbutoxy)-coumarin.     

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.     

Three new neolignan glucosides from the stems of Dendrobium aurantiacum var. denneanum

Three new neolignan glucosides (1–3), together with four known analogs (4–7), have been isolated from the stems of Dendrobium aurantiacum var. denneanum. Structures of the new compounds including the absolute configurations were determined by spectroscopic and chemical methods as (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (1), (−)-(8S,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (2), and (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′,9′-pentamethoxy-8,4′-oxyneolign-7′-ene-9-ol 4,9-bis-O-β-d-glucopyranoside (3), respectively.     

Rubrenolide and rubrynolide: An alkene-alkyne pair from Nectandra rubra

Structures are proposed for rubrenolide, (2S,4R)-2-[(2′S)-2′,3′-dihydroxypropyl]-4-(dec-9′'-enyl)-γ-lactone, and rubrynolide, (2S,4R)-2-[(2′S)-2′,3′-dihydroxypropyl]-4-(dec-9′'-ynyl)-γ-lactone, isolated from Nectandra rubra (Lauraceae).     

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).     

A chalcone glycoside from Abies pindrow

The EtOH extract of air-dried stems of Abies pindrow yielded okanin, okanin 4′-O-β-d-glucopyranoside, butein 4′-O-β-d-glucopyranoside, 8,3′4′-trihydroxyflavanone-7-O-β-d-glucopyranoside and a new chalcone glycoside, 2′,3′,4′:3,4-pentahydroxy-chalcone 4′-(l-arabinofuranosyl-α-1→4-d-glucopyranoside-β).     

Conversion of (2Z,4E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid to xanthoxin acid by Cercospora cruenta, a fungus producing (+)-abscisic acid

(±)-(2Z,4E)-5-(1′,2′-epoxy-2′,6′,6′-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid was metabolized by Cercospora cruenta, which has the ability to produce (+)-abscisic acid (ABA), to give (±)-(2Z,4E)-xanthoxin acid, (±)-(2Z,4E)-5′-hydroxy-1′,2′-epoxy-1′,2′-dihydro-β-ionylideneacetic acid, (±)-1′,2′-epoxy-1′,2′-dihydro-β-ionone and trace amounts of ABA.     

A quinone-hydroquinone couple from the Brown alga Cystoseira stricta

2′E,6′E)-2-(10′,11′-Dihydroxygeranylgeranyl)-6-methylquinol and 2′E,6′E)-2(10′,11′-dihydroxyeranylgeranyl)-6-methyl-1,4-benzoquinone have been isolated from the brown alga Cystoseira stricta. The structures of the new algal metabolites have been elucidated by spectral analysis and chemical degradation.     

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.     

Flavonoids of the liverwort Marchantia polymorpha

The major flavonoids of Marchantia polymorpha var. polymorpha and aquatica are the 7-O-β-d-glucuronides of apigenin and luteolin, luteolin 3′-O-β-d-glucuronide, luteolin 7,3′-di-O-β-d-glucuronide, and the 7,4′-di-O-β-d-glucuronides of apigenin and luteolin. These are accompanied by minor amounts of apigenin, luteolin, luteolin 3′,4′-di-O-β-d-glucuronide and luteolin 7,3′,4′-tri-O-β-d-glucuronide. All the luteolin di- and triglucuronides except the 3′,4′-di- substituted compound are new natural products.     

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].     

Minor Carotenoid Sulfates from lanthella basta

The structural elucidation of the minor carotenoid sulfates from the marine sponge lanthella basta is discussed in context with the structure assigned to the major sulfate bastaxanthin (c; 3,19,17′-trihydroxy-7,8-didehydro-β-κ-carotene-3′,6′-dione 3-sulfate. Plausible structures are assigned to other bastaxanthins (b,b₂, c₂, d, e and f) on the basis of electroic, IR, ¹H NMR, mass and CD spectra, electrophoretic behaviour, chemical derivatization and enzymatic or acid-catalysed hydrolysis. The minor sulfates represent structural variation in the cylopentane end group with different oxidation levels. Bastaxanthol b (desulfated bastaxanthin b) was a minor carotenoid constituent of l. basta. Including tentative chiralities, the structures favoured for the bastaxanthins are: c₂, (3R,3′R, 5′R)-3,19,3′-trihydroxy-7,8-didehydro-β,κ-caroten-6′-one 3-sulfate; b₂, (3R,3′R,5′R)-3, 19-dihydroxy-7,8-didehydro-β,κ- dione 3-sulfate; b, (3R,1′R, 5′R)-3, 19-dihydroxy 3′,6′-dioxo-7,8-didehydro-β,κ-caroten-17′-al 3-sulfate; d. (3R,1′R,3′R,5′R)-3, 19,3′,17′-tetrahydroxy 7,8 didehydro-β,κ-caroten-6′-one 3-sulfate; e. hydrogen (3R,1′R,5′R)-3, 19-dihydroxy-3′,6′-dioxo-7,8-didehydro-β,κ-caroten-17′-oate 3 sulfate (?); and f, hydrogen (3R.1′R,3′R,5′R)-3,19,3′-trihydroxy-7,8-didehydro-6′-oxo-β,κ-caroten-17′-oate 3-sulfate; for bastaxanthol b(3R.1′R.5′R)-3, 19-dihydroxy-3′,6′-dioxo-7,8-didehydro-β,κ-caroten-17′-al. The bastaxanthins are considered as metabolic products of l. basta, diadinoxanthin of phytoplankton origin representing a plausiable precursor.     

Configurational studies on red algae carotenoids

The configurations of (6′R)-β,ε-carotene, (3′R,6′R)-β,ε-caroten-3′-ol (α-cryptoxanthin), (3R,3′R,6′R)-β,ε-carotene-3,3′-diol (lutein), (3R)-β,β-caroten-3-ol (β-cryptoxanthin), (3R,3′R)-β,β-carotene-3,3′-diol (zeaxanthin) and all-trans (3S,5R,6S,3′R)-5,6-epoxy-5,6-dihydro-β,β-carotene-3,3′-diol (antheraxanthin) were established by CD and ¹H NMR studies. The red algal carotenoids consequently possessed chiralities at each chiral center (C-3, C-5, C-6, C-3′, C-6′), corresponding to the chiralities established for the same carotenoids in higher plants. Two post mortem artifacts from Erythrotrichia carnea were assigned the chiral structures (3S,5R,8R,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8R)-mutatoxanthin] and (3S,5R,8S,3′R)-5,8-epoxy-5,8-dihydro-β,β-carotene-3,3′-diol [(8S)-mutatoxanthin]. This is the first well documented report of a naturally occurring β,ε-caroten-3′-ol (¹H NMR, CD, chemical derivatization).     

Isolation and structural elucidation of cucurbitaxanthin a and b from pumpkin cucurbita maxima

Two new carotenoids, cucurbitaxanthin A [(3S,5R,6,R3′R)-3,6-epoxy-5,6-dihydro-β,β-carotene-5,3′-diol] and cucurbitaxanthin B [(3S,5R,6R,3′S,5′R,6′S)-3,6,5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β-β-carotene-5,3′-diol] have been isolated from the pumpkin Cucurbita maxima.     

Unique flavonoid glycosides from the new zealand white pine, Dacrycarpus dacrydioides

A number of new flavonoid glycosides have been isolated from foliage of the New Zealand white pine, Dacrycarpus dacrydioides. These include tricetin 3′,5′-di-O-β-glucopyranoside; the 3′-O-β-xylopyranoside, 7-O-α-rhamnopyranoside and 7-O-α-rhamnopyranoside-3′-O-β-xylopyranoside of 3-O-methylmyricetin; the 3′-O-β-xylopyranoside, 7-O-α-rhamnopyranoside and 7-O-α-rhamnopyranoside-3′-O-β-xylopyranoside of 3-O-methyl-quercetin, and the 3′-O-β-xylopyranoside and 7-O-α-rhamnopyranoside-3′-O-β-xylopyranoside of 3,4′-di-O-methylmyricetin. The accumulation of 3-methoxyflavones and B-ring trioxygenated flavonoids appears to distinguish D. dacrydioides from all other New Zealand members of the classical genus Podocarpus. Support for De Laubenfels' proposed separation of Dacrycarpus from this genus is seen in the present work.     

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.     

On the non-existence of eloxanthin

Abandonment of the name eloxanthin is proposed. The principal carotenoids in various species of Elodea were (3R, 3′R, 6′R)-lutein (β,ε-carotene-3, 3′-diol) and β, β-carotene. The minor pigments were neoxanthin-X (5′, 6′-epoxy-6, 7-didehydro-5, 6, 5′, 6′-tetrahydro-β, β-carotene-3, 5, 3′-triol), 9′-cis-neoxanthin- X, 9- and 13-cis-violaxanthin (5, 6, 5′, 6′-diepoxy-5, 6, 5′, 6′-tetrahydro-β, β-carotene-3, 3′-diol), antheraxanthin (5, 6-epoxy-5, 6-dihydro-β, β-carotene-3, 3′-diol), neolutein A (13- or 13′-cis-lutein) and neolutein B (9- or 9′-cis-lutein). All attempts to isolate eloxanthin failed.     

Occurrence of some mono-cis-isomers of asymmetric C40-carotenoids

The 9-cis-isomers of antheraxanthin [(3S,5R,6S)-5,6-epoxy-5,6- dihydro-β, β-carotene-3,3′-diol] and lutein epoxide [(3S,5R,6S, 3′R,6′R)-5,6-epoxy-5,6-dihydro-β, ε-carotene-3,3′-diol] were found to occur without their 9′-cis counterparts in the non-photosynthetic tissues of several higher plants. 9-cis-lutein [(3R,3′R,6′R)- β,ε-carotene-3,3′-diol], on the other hand, was observed together with its 9′-cis counterpart in the samples investigated. The qualitative distribution of carotenoids is also reported.