Isoflavones from Pterodon apparicioi

The trunk wood of Pterodon apparicioi contains five known compounds: 7-hydroxy-6,4′-dimethoxy-, 7-hydroxy-6-methoxy-3′,4′-methylenedioxy-, 6,7,2′,3′,4′-pentamethoxy-, 6,7,2′,4′,5′-pentamethoxy- and 6,7,2′-trimethoxy-4′,5′-methylenedioxyisoflavone. In addition, there are four new substances, namely 7,3′-dihydroxy-6,4′-dimethoxy-, 7-hydroxy-6,2′,4′,5′-tetramethoxy-, 7,2′-dimethoxy-4′,5′-methylenedioxy- and 7,8,2′-trimethoxy-4′,5′-methylenedioxyisoflavone.     

Biosynthesis of the isoflavan isomucronulatol: Origin of the 2′,3′,4′-oxygenation pattern

Feeding experiments with ¹⁴C-labelled isoflavones in seedlings and pods of bladder senna (Colutea arborescens) have demonstrated that 7-hydroxy-4′-methoxyisoflavone (formononetin), 7,3′-dihydroxy-4′-methoxyisoflavone (calycosin), 7,2′,3′-trihydroxy-4′-methoxyisoflavone (koparin) and 7,2′-dihydroxy-3′,4′-dimethoxyisoflavone are excellent precursors of (3R)-isomucronulatol (7,2′-dihydroxy-3′,4′-dimethoxyisoflavan). 7,2′-Dihydroxy- 4′-methoxyisoflavone (2′-hydroxyformononetin) and 7-hydroxy-3′,4′-dimethoxyisoflavone (cladrin) were, however, poor substrates. Thus, the biosynthetic sequence to isomucronulatol from formononetin involves 3′-hydroxylation, 2′-hydroxylation and then 3′-O-methylation, followed presumably by stereospecific reduction of 7,2′-dihydroxy-3′,4′-dimethoxyisoflavone. Treatment of 2′,3′,4′-trimethoxyisoflavones with aluminium chloride in acetonitrile gives modest yields of 2′,3′-dihydroxy derivatives rather than 2′-monohydroxyisoflavones, and thus provides a convenient access to 2′,3′-dihydroxyisoflavones and related pterocarpans.     

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].     

Two new flavones from Eupatorium coelestinum

Besides coumarin, nobiletin, lucidin dimethyl ether and 5,6,7,3′,4′-pentamethoxyflavone, two new highly oxygenated flavones were isolated from Eupatorium coelestinum. Their structures were determined by spectroscopic methods and alkaline degradations as 5,6,7,8,3′,4′,5′ -heptamethoxyflavone and 5,6,7,8,5′-pentamethoxy-3′,4′-methylenedioxyflavone.     

Highly oxygenated flavonoids from Ageratum corymbosum

The investigation of Ageratum corymbosum resulted in the isolation of four new highly oxygenated flavonoids, and their structures established by spectroscopic and degradative evidence as 5,6,7,5′-tetramethoxy-3′,4′-methylenedioxyflavanone; 5,6,7,8,5′-pentamethoxy-3′,4′-methylenedioxyflavanone; 5,6,7,8,2′,4′,5′-heptamethoxy-flavone and 5,2′,4′-trihydroxy-6,7,8,5′-tetramethoxyflavone. The recently reported gardenin A monomethyl ether and 5′-methoxylucidin dimethyl ether (eupalestin) were also isolated.     

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.     

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 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).     

Four flavonoids from Ageratum strictum

Four new flavonoids, three flavanones and one chalcone, were isolated from aerial parts of Ageratum strictum. Their structures were establised as 3′6′-dihydroxy-2′, 4′-dimethoxy- 3, 4-methylenedioxy-chalcone, 6-hydroxy-5,7-dimethoxy-3′,4′-methylenedioxyflavanone, 6-hydroxy- 5,7,3′,4′-tetramethoxyflavanone and 6,4′-dihydroxy-5,7,3′-trimethoxyflavanone on the basis of spectral data and chemical degradation.     

A convenient synthesis of 6′-C-substituted β-maltose heptaacetates and of panose

Benzylidenation of β-maltose monohydrate with α,α-dimethoxytoluene in N,N-dimethylformamide in the presence of p-toluenesulfonic acid gave, in 70% yield, 4′,6′-O-benzylidenemaltose, which was acetylated to afford, 1,2,3,6,2′,3′-hexa-O-acetyl-4′,6′-O-benzylidene-β-maltose (4). Removal of the benzylidene group of 4 gave 1,2,3,6,2′,3′-hexa-O-acetyl-β-maltose (5), which was transformed into 1,2,3,6,2′,3′,4′-hepta-O-acetyl-6′-O-p-tolylsulfonyl-β-maltose (8). Several 6′-substituted β-maltose heptaacetates were synthesized by displacement reactions of 8 with various nucleophiles. Condensation of 5 with 2,3,4,6-tetra-O-benzyl-α-d-glucopyranosyl bromide, under catalysis by halide ion, followed by removal of protecting groups, furnished panose in good yield.     

Isoflavones from Xanthocercis zambesiaca

In addition to the previously described 7-hydroxy-8,4′-dimethoxy- and 7,3′-dihydroxy-8,4′-dimethoxy-isoflavone the heartwood of Xanthocercis zambesiaca has been shown to contain 7-hydroxy-8,3′,4′-trimethoxy-,3′,4′-dimethoxy-6,7-methylenedioxy- and 8,3′,4′-trimethoxy-6,7-methylenedioxy-isoflavone. A technique of determining isoflavone hydroxylation patterns by deuterium labelling is described.     

Flavonoids from Artemisia ludoviciana var. ludoviciana

Nineteen flavonoids were isolated from Artemisia ludoviciana var. ludoviciana, including a new 2′- hydroxy- 6-methoxyflavone, 5,7,2′,4′-tetrahydroxy-6,5′-dimethoxyflavone. The known compounds include quercetagetin 3,6,3′,4′-tetramethyl ether, eupatilin, 5,7-dihydroxy-3,6,8,4′-tetramethoxyflavone, luteolin 3′,4′-dimethyl ether, jaceosidin, 5,7,4′-trihydroxy-3,6-dimethoxyflavone, tricin, hispidulin, chrysoeriol, kaempferol 3-methyl ether, apigenin, axillarin, eupafolin, selagin and luteolin together with three flavones which were previously isolated for the first time from Artemisia frigida: 5,7,4′-trihydroxy-6, 3′,5′-trimethoxyflavone, 5,7,3′-trihydroxy-6,4′,5′-trimethoxyflavone and 5,7,3′,4′-tetrahydroxy-6,5′- dimethoxyflavone.     

Diarylpropanoids from Iryanthera polyneura

The trunk wood of Iryanthera polyneura Ducke (Myristicaceae) contains pinocembrin, 1-(2′,4′-dihydroxyphenyl)-3-(3″,4″-methylenedioxyphenyl)-propane, 1-(2′,4′-dihydroxy-3′-methylphenyl)-3-(2″-methoxy-4″, 5″-methylenedioxyphenyl)-propane and 4,2′,4′-trihydroxy-3-methoxydihydrochalcone.     

Flavonoids of Chrysosplenium tetrandrum

Chrysosplenium tetrandrum, from northern British Columbia, accumulates a variety of flavonoid glycosides. Several kaempferol and quercetin mono- and diglycosides were identified. The major flavonoid fraction consisted of O-methylated compounds having an hydroxyl or methoxyl substituent at position-6. Aglycones identified were 5,4′-dihydroxy-3,6,7-trimethoxyflavone, 5,6,7,3′,4′-pentahydroxy-3-methoxyflavone, 5,6,3′,4′-tetrahydroxy-3,7-dimethoxyflavone, 5,6,4′-trihydroxy-3,7,3′-trimethoxyflavone, 5,3′,4′-trihydroxy-3,6,7-trimethoxyflavone, and 5,4′-dihydroxy-3,6,7,3′-tetramethoxyflavone. All occurred as glucosides. The occurrence of 6-substitution and the preponderance of O-methylated flavonoids supports removal of Chrysosplenium from Engler's Saxifraginae.     

Highly oxygenated flavones from Mentha piperita

Six highly oxygenated flavones have been isolated from the leaves of Mentha piperita. Five known compounds, 5-hydroxy-6,7,8,4′-tetramethoxyflavone, 5,4′-dihydroxy-6,7,8-trimethoxyflavone, 5,3′-dihydroxy-6,7,8,4′-tetramethoxyflavone, 5-hydroxy-6,7,8,3′,4′-pentamethoxyflavone and 5,3′,4′-trihydroxy-6,7,8-trimethoxyflavone, are reported for the first time in the genus Mentha. The sixth compound has been identified as 5,6-dihydroxy-7,8,3′,4′-tetramethoxyflavone by UV, NMR and mass spectra.     

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.     

Der substitutionsspezifische einfluss von chalkonen auf die anthocyanbiosynthese bei Petunia hybrida

The effect of two chalcones, 3,4,2′,4′,6′-pentahydroxy- and the 4, 2 ′,4′,6′ -tetrahydroxy- 3-methoxy-chalcone- 4′-glucoside, on the synthesis of different flower anthocyanins in isolated petals of Petunia hybrida has been investigated. The results show that the synthesis of those anthocyanins, which have the same substitution pattern as the chalcone used was increased. This suggests that the chalcones are incorporated into the anthocyanins concerned. When the chalcones were fed together with acetic acid-[1-¹⁴C], this specific substitution effect was detectable only for the 3,4,2′,4′,6′-pentahydroxy-chalcone-4′-glucoside.     

The synthesis of 4′,6′-diacetamido-4′,6′-dideoxycellobiose hexa-acetate from lactose

Reaction of methyl 4′,6′-di-O-mesyl-β-lactoside pentabenzoate (8), synthesised via the 4′,6′-O-benzylidene derivative (6), with sodium azide in hexamethylphosphoric triamide gave three products. In addition to the required 4′,6′-diazidocellobioside (9), an elimination product, methyl 4-O-(6-azido-2,3-di-O-benzoyl-4,6-dideoxy-α-L-threo-hex-4-enopyranosyl)-2,3,6-tri-O-benzoyl-β-D-glucopyranoside (12), and an unexpected product of interglycosidic cleavage, methyl 2,3,6-tri-O-benzoyl-β-D-glucopyranoside (13), were formed. The origin of the latter product is discussed. The diazide 9 was converted into 4′,6′-diacetamido-4′,6′-dideoxycellobiose hexa-acetate (16) by sequential debenzoylation, catalytic reduction, acetylation, and acetolysis.     

New substituted bibenzyls of Frullania brittoniae subsp. Truncatifolia

The two dihydrostilbenes, Brittonin A and Brittonin B, have been isolated from Frullania brittoniae subsp. truncatifolia (F. F. muscicola). They were identified as 3,4,5,3′,4′,5′-hexamethoxybibenzyl and 3,4,5,3′-tetra- methoxy-4′,5′,-methylenedioxybibenzyl respectively.     

Isoflavonoids from Myroxylon peruiferum

Considerable differences in flavonoid composition of the trunkwood characterize different specimens of Myroxylon balsamum (L.) Harms. Only calycosin among the 11 flavonoids found in M. peruiferum L.f., presently considered synonymous with M. balsamum, had previously been located in the latter species. Two of these flavonoids, 2′-hydroxy-7,3′,4′-trimethoxyisoflavanone and 2′-hydroxy-7,3′,4′-trimethoxyisoflavone are new natural products.