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.     

Pyranocoumarin derivatives from Seseli tortuosum

Trans-khellactone, cis-khellactone, 3′-senecioyl-cis-khellactone, 3′-senecioyl-4′-acetyl-cis-khellactone, 4′-senecioyl-cis-khellactone, 3′-acetyl-4′-senecioyl-cis-khellactone, 3′,4′-di-isovaleryl-cis-khellactone, 3′,4′-disenecioyl-cis-khellactone, 3′-angeloyl-4′-isovaleryl-cis-khellactone and 3′-isovaleryl-4′-angeloyl-cis-khellactone were obtained from the aerial part of Seseli tortuosum.     

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.     

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.     

Occurrence of juvabione-type and epijuvabione-type sesquiterpenoids in Abies alba

The petrol-soluble fractions from the branchwood of four Abies alba trees were examined. Only two trees contained sufficient amounts of ‘juvabione-type’ insect juvenile hormone analogues for isolation and characterization. The first contained juvabione (4R, 1′R), 4′-dehydrojuvabione (4R, 1′R) and its 4R, 1′S diastereomer in a ratio of 3:1, and juvabiol (4R, 1′R, 3′S), isojuvabiol (4R, 1′R, 3′R) and epijuvabiol (4R, 1′S, 3′S) in an approximate ratio of 7:3:2. 4′-Dehydroepijuvabione (4R, 1′S) was the only ‘juvabione-type’ compound ioslated from the second tree. If it is accepted that juvabione and epijuvabione are enzymatically reduced forms of dehydrojuvabione and dehydroepijuvabione, respectively; then for these two A. alba our results indicate that only one enzyme which is specific for R chirality at C-1′ is present, since epijuvabione is not observed.     

Allele-specific marker development and selection efficiencies for both flavonoid 3′-hydroxylase and flavonoid 3′,5′-hydroxylase genes in soybean subgenus soja

Color is one of the phenotypic markers mostly used to study soybean (Glycine max L. Merr.) genetic, molecular and biochemical processes. Two P450-dependent mono-oxygenases, flavonoid 3′-hydroxylase (F3′H; EC1.14.3.21) and flavonoid 3′,5′-hydroxylase (F3′5′H, EC1.14.13.88), both catalyzing the hydroxylation of the B-ring in flavonoids, play an important role in coloration. Previous studies showed that the T locus was a gene encoding F3′H and the W1 locus co-segregated with a gene encoding F3′5′H in soybean. These two genetic loci have identified to control seed coat, flower and pubescence colors. However, the allelic distributions of both F3′H and F3′5′H genes in soybean were unknown. In this study, three novel alleles were identified (two of four alleles for GmF3′H and one of three alleles for GmF3′5′H). A set of gene-tagged markers was developed and verified based on the sequence diversity of all seven alleles. Furthermore, the markers were used to analyze soybean accessions including 170 cultivated soybeans (G. max) from a mini core collection and 102 wild soybeans (G. soja). For both F3′H and F3′5′H, the marker selection efficiencies for pubescence color and flower color were determined. The results showed that one GmF3′H allele explained 92.2 % of the variation in tawny and two gmf3′h alleles explained 63.8 % of the variation in gray pubescence colors. In addition, two GmF3′5′H alleles and one gmF3′5′h allele explained 94.0 % of the variation in purple and 75.3 % in white flowers, respectively. By the combination of the two loci, seed coat color was determined. In total, 90.9 % of accessions possessing both the gmf3′h-b and gmf3′5′h alleles had yellow seed coats. Therefore, seed coat colors are controlled by more than two loci.     

Flavonoids from Millettia pulchra

Chemical examination of Millettia pulchra yielded (?)-maackiain, (?)-pterocarpin, (?)-sophoranone and the new compounds (6S, 6aS, 11aR)-6α-methoxypterocarpin, (6S, 6aS,11aR)-6α-methoxyhomopterocarpin, (2S)5,7,4′-trihydroxy-8,3′,5′-triprenylflavanone, (2R,3R)7,4′-dihydroxy-8,3′,5′-triprenyldihydroflavanol, 5,7,2′,4′-tetrahydroxy-6,3′-diprenylisoflavone and 5,7,4′-trihydroxy-2′-methoxy-6,3′-diprenylisoflavone.     

Flower-specific expression of the Phalaenopsis flavonoid 3′, 5′-hydoxylase modifies flower color pigmentation in Petunia and Lilium

Flavonoid 3′, 5′-hydoxylase (F3′5′H) is a key enzyme for biosynthesis of the blue anthocyanin pigment delphinidin. A number of F3′5′H genes from dicots have been tested for their effects on flower pigmentation; here F3′5′H from a monocot was tested for its effect on delphinidin accumulation in petals. To this end, F3′5′H (PhF3′5′H) from the orchid Phalaenopsis was expressed under the control of the chalcone synthase promoter in petunia flowers. Quantitative RT-PCR showed that PhF3′5′H was expressed mainly in the petal limb; this expression produced an increase in dihydromyricetin and delphinidin and a change in petal color from pink to deeper pink. To increase the accumulation of delphinidin, Hyacinth HyDFR, which encodes dihydroflavonol 4-reductase, and petunia DifF, which encodes a cytochrome b ₅ that is required for full activity of F3′5′H were overexpressed. The HyDFR petunia transformants had a deeper color petal limb, increased dihydromyricetin and delphinidin contents and adaxial petals with a number of blue cells. The flowers of the DifF petunia transformants also showed a slight color change. We also tested PhF3′5′H in Lilium oriental ‘Sorbonne’, where transient PhF3′5′H expression by particle bombardment resulted in purple cells in the petals. Production of blue flowers by Phalaenopsis F3′5′H and hyacinth DFR potentially enables manipulation of flower color in ornamental plants, including production of blue flowers.     

Absolute configuration of heteroxanthin and diadinoxanthin

The absolute configurations of heteroxanthin ((3S,5S,6S,3′R)- 7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,5,3′,6′-tetrol) ex Euglena gracilis and of diadinoxanthin ((3S,5R,6S,3′R)-5,6-epoxy-7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,3′-diol) from the same source have been established by chemical reactions, hydrogen bonding studies, ¹H NMR and CD. Two previously unknown carotenoids (artefacts?) from Trollius europaeus, assigned the structures (3S,5S,6S,3′S,5′R,6′R)-6,7-didehydro-5,6,5′,6′-tetrahydro-β,β -carotene-3,5,6,3′,5′-pentol and its 5R epimer, served as useful models.     

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.     

Synthesis of 4′-C-aminoalkyl-2′-O-methyl modified RNA and their biological properties

In this paper, we describe the synthesis of 4′-C-aminoalkyl-2′-O-methylnucleosides and the properties of RNAs containing these analogs. Phosphoramidites of 4′-C-aminoethyl and 4′-C-aminopropyl-2′-O-methyluridines were prepared using glucose as starting material, and RNAs containing the analogs were synthesized using the phosphoramidites. Thermal denaturation studies revealed that these nucleoside analogs decreased the thermal stabilities of double-stranded RNAs (dsRNAs). Results of NMR, molecular modeling, and CD spectra measurements suggested that 4′-C-aminoalkyl-2′-O-methyluridine adopts an C2′-endo sugar puckering in dsRNA. The 4′-C-aminoalkyl modifications in the passenger strand and the guide strand outside the seed region were well tolerated for RNAi activity of siRNAs. Single-stranded RNAs (ssRNAs) and siRNAs containing the 4′-C-aminoethyl and 4′-C-aminopropyl analogs showed high stability in buffer containing bovine serum. Thus, siRNAs containing the 4′-C-aminoethyl and 4′-C-aminopropyl analogs are good candidates for the development of therapeutic siRNA molecules.     

Synthesis and properties of 4′-C-aminoalkyl-2′-fluoro-modified RNA oligomers

Synthesis and properties of double-stranded RNAs (dsRNAs) and small interfering RNAs (siRNAs) containing 4′-C-aminoethyl-2′-deoxy-2′-fluorouridine are described. Thermal denaturation studies showed that incorporation of 4′-C-aminoethyl-2′-fluoro analog improved the thermal stabilities of dsRNAs and siRNAs compared to the corresponding 4′-C-aminoethyl-2′-O-methyl analog. siRNA incorporating eight 4′-aminoethyl-2′-fluoro analogs in the passenger strand showed sufficient RNAi activity at 1?nM concentration, which was similar to that of the unmodified siRNA. Furthermore, the siRNA containing the 4′-C-aminoethyl-2′-fluoro analog exhibited high stability in a buffer containing 20% bovine serum. Forty-eight percent of the siRNA remained intact after 48?h of incubation. Thus, modification of siRNAs by the 4′-C-aminoethyl-2′-fluoro analog would be useful for the development of therapeutic siRNA molecules.     

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.     

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.     

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.     

Inhibition of the peptidyl transferase A-site function by 2'-O-aminoacyloligonucleotides

New “non-isomerizable” analogs of the 3′-terminus of AA-tRNA, C-A(2′Phe)H, C-A(2′Phe)Me, C-A(2′H)Phe and C-A(2′Me)Phe, were tested as acceptor substrates of ribosomal peptidyl transferase and inhibitors of the peptidyl transferase A-site function. The 3′-O-AA-derivatives were active acceptors of Ac-Phe in the peptidyl transferase reaction, while the 2′-O-AA-derivatives were completely inactive. Both 2′- and 3′-O-AA-derivatives were potent inhibitors of peptidyl transferase catalyzed Ac-Phe transfer to puromycin. The results indicate that although peptidyl transferase exclusively utilizes 3′-O-esters of tRNA as acceptor substrates, its A-site can also recognize the 3′-terminus of 2′-O-AA-tRNA.     

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).     

Prenylated flavonoids from seeds of Calopogonium mucunoides

The seeds of Calopogonium mucunoides furnished 7-O-γ,γ-dimethylallyl-8-methoxy-3′,4′-dioxymethylene-isoflavone, 7-O-γ,γ-dimethylallyl-3′-hydroxy-4′-methoxyisoflavone, 7-O-γ,γ-dimethylallyl-3′,4′-dimethoxyisoflavone and 2S-di[6′',6′'-dimethylpyrano (2′',3′':7,8;2′',3′':4′,3′)]-flavanone whose structures were established by spectroscopic means involving the use of 400 MHz ¹H NMR with double irradiation and INDOR techniques.     

Lipophilic C-methylflavonoids with no B-ring oxygenation in Metrosideros species (Myrtaceae)

Five unusual C-methylflavonoids lacking B-ring oxygenation (2′,4′-dihydroxy-3′,5′-dimethyl-6′-methoxychalcone, 2′,4′-dihydroxy-3′-methyl-6′-methoxychalcone, 2′,6′-dihydroxy-3′-methyl-4′-methoxychalcone, 2′-hydroxy-3′-methyl-4′,6′-dimethoxychalcone and 5,7-dihydroxy-6,8-dimethylflavanone) were found for the first time in Metrosideros excelsa. The flavanone was the major constituent in leaves, whereas 2′,6′-dihydroxy-3′-methyl-4′-methoxychalcone dominated all other aerial plant parts studied. Other Metrosideros species were investigated for these five flavonoids. C₁₉–C₃₆ aldehydes and C₂₂–C₃₂ alcohols were also identified from the dried seed capsules of M. excelsa.     

New water soluble flavone and xanthone glycosides from Hypericum canariense L.

The water soluble portion of the aerial parts of Hypericum canariense L. yielded after acetylation the 5,7,3′4′-tetra- and 7,3′4′-triacetates of a new flavonoid 5,7,3′,4′-tetrahydroxy-3-O-β-d-(methyl 2,3,4-triacetoxypyranuronyl)-quercetin, the 3′-acetate of a new flavonoid 3′-hydroxy-5,7,4′-trimethoxy-3-O-β-d-(methyl 2,3,4-triacetoxypyranuronyl)-quercetin, the 3′-acetate and the 3′5′-diacetate of the new flavonoid 5,3′dihydroxy-7,4′-dimethoxy-3-β-d-(methyl 2,3,4-triacetoxypyranuronyl)-quercetin, the xanthone derivative mangiferin 2′,3′,4′,6′-tetraacetate and the latter's new 1,3,6,7′-tetramethoxy, 1,3,6-trimethoxy-4-acetoxy and 1,7-diacetoxy-3,6-dimethoxy analogs.