A 4-arylcoumarin from Coutarea hexandra

The structure of a new 4-arylcoumarin, isolated from Coutarea hexandra, has been established as 5,7-dimethoxy-3′,4′-methylenedioxy-4-phenylcoumarin and confirmed by partial synthesis from 3′,4′-dihydroxy-5,7-dimethoxy-4-phenylcoumarin.     

Homoisoflavonoids from the inter-bulb surfaces of Scilla nervosa subsp. rigidifolia

Eight homoisoflavonoids, two of which are new: 3-(4′-methoxybenzyl)-5,6,7-trimethoxychroman-4-one (1); 3-(4′-methoxybenzyl)-5,7-dimethoxychroman-4-one (2); 3-(4′-methoxybenzyl)-7-hydroxy-5,6-dimethoxychroman-4-one (3); 3-(4′-methoxybenzyl)-6-hydroxy-5,7-dimethoxychroman-4-one (4); 3-(3′-hydroxy-4′-methoxybenzyl)-5,7-dihydroxy-6-methoxychroman-4-one (5); 3-(3′-hydroxy-4′-methoxybenzyl)-5,7-dihydroxychroman-4-one (6); 3-(4′-hydroxybenzylidene)-5,7-dihydroxy-6-methoxychroman-4-one (7) and 3-(4′-hydroxybenzylidene)-5,7-dihydroxychroman-4-one (8), were isolated from the yellow Inter-bulb deposits from Scilla nervosa. The structures of these compounds were elucidated and characterized by 1D- and 2D-NMR and mass spectrometry. The structures of the known compounds were compared to those ones in literature.     

4-Arylcoumarins from Coutarea hexandra

Four new 4-arylcoumarins have been isolated from Coutarea hexandra and their structures established as 5,7,4′-trimethoxy-4-phenylcoumarin, 4′-hydroxy-5,7-dimethoxy-4-phenylcoumarin, 3′-hydroxy-5,7-4′-trimethoxy-4-phenylcoumarin and 3′,4′-dihydroxy-5,7-dimethoxy-4-phenylcoumarin.     

7,2′,4′-Trihydroxy-3′-methoxyisoflavone from zollernia paraensis

Three further compounds have been isolated from Zollernia paraensis: 2,7-dihydroxy-4′-methoxy-3-phenylcoumarin, (±)-5,7-dihydroxy-2′,4′-dimethoxyisoflavanone and the new 7,2′,4′-trihydroxy-3′-methoxyisoflavone.     

Propolis with high flavonoid content collected by honey bees from Acacia paradoxa

Honey bees, Apis mellifera var ligustica, on Kangaroo Island, Australia, were found to collect propolis from the sticky exudate on the stem shoots and seed pods of an Australian endemic plant, Acacia paradoxa. Extracts of the plant stem shoots and seed pods, the propolis carried on the legs of bees and freshly collected propolis in hives contained major flavonoid components consisting of 2′,3′,4′-trimethoxychalcone, 2′-hydroxy-3′,4′-dimethoxychalcone, 2′,4′-dihydroxy-3′-methoxychalcone, 5,7-dihydroxy-2,3-dihydroflavonol 3-acetate (pinobanksin 3-acetate) and 5,7-dihydroxy-6-methoxy-2,3-dihydroflavonol 3-acetate, a substance not previously characterized. HPLC and ¹H NMR analyses of the propolis and plant extracts indicated smaller amounts of other flavonoids. A survey of propolis samples from 47 apiary sites widely distributed on Kangaroo Island showed that 15 samples from 6 sites were largely sourced from A. paradoxa.     

A new homoisoflavonoid and the bioactivities of some selected homoisoflavonoids from the inter-bulb surfaces of Scilla nervosa subsp. rigidifolia

Seven homoisoflavonoids and one stilbenoid, 3-(4′-methoxybenzyl)-6,7-dihydroxy-5-methoxychroman-4-one (1) which is new; 3-(4′-methoxybenzyl)-6-hydroxy-5,7-dimethoxychroman-4-one (2); 3-(4′-methoxybenzyl)-5,7-dimethoxychroman-4-one (3); 3-(3′-hydroxy-4′-methoxybenzyl)-5,7-dimethoxychroman-4-one (4); 3-(4′-methoxybenzylidene)-5,7-dihydroxy-6-methoxychroman-4-one (5); 3-(4′-hydroxybenzylidene)-5,7-dihydroxy-6-methoxychroman-4-one (6); 3-(4′-hydroxybenzylidene)-5,7-dihydroxychroman-4-one (7) and 4,3′,5′-trihydroxy-3-methoxystilbene (8), were isolated from the yellow inter-bulb deposits from Scilla nervosa. The structures of these compounds were elucidated by 1D- and 2D-NMR and mass spectrometry. A number of extracts, fractions and compounds tested displayed bacterostatic activity with MICs ranging between 0.156 and 1.250 mg/ml. Two extracts displayed significant α-glucosidase inhibitory activity and a number of extracts, fractions and compounds showed strong antioxidant activity with, compounds 1, 2 and 8 displaying lower MECs than the positive control ascorbic acid (0.0156 mg/ml).     

Two new flavonoids from Derris laxiflora Benth

Two new compounds, derriscoumaronochromone (1) and cis-3,4′-dihydroxy- 5,7-dimethoxyflavan (2), as well as trans-4'-O-methylcatechin (3) were isolated from Derris laxiflora, The structures of these compounds were determined by analysis of their spectroscopic data.     

Flavonoids from Pinus morrisonicola

Two dihydroflavonols, (2R,3R-3-acetoxy-5,7-dihydroxy-6-methylflavanone and (2R,3R-3,5,7-trihydroxy-6-methylflavanone, accompanied by 12 known flavonoids were isolated from the acetone extract of the heartwood of Pinus morrisonicola. The major flavonoids include chrysin, pinobanksin and tectochrysin.     

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.     

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.     

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.     

Isoflavone evolution in Monopteryx

Monopteryx inpae contains six 5,7-dihydroxyisoflavones, three of which, such as the novel 5,7-dihydroxy-8,3′,4′-trimethoxy derivative, have additionally methoxyls on ring A. All three isoflavones of M. uaucu are, by contrast, 7-hydroxy-8-methoxy derivatives. From the chemical standpoint, the former species thus appears to be more primitive than the latter.     

5,7-dihydroxy-3,8,3′,4′-tetramethoxyflavone from Parastrephia quadrangularis

A new flavone has been isolated from Parastrephia quadrangularis and identified as 5,7-dihydroxy-3,8,3′,4′-tetramethoxyflavone.     

5,6,7-Trisubstituted flavones from Gomphrena martiana

Two 5,6,7-trisubstituted flavones have been isolated from Gomphrena martiana and identified as 5,6-dimethoxy-7-hydroxyflavone and 5,7-dihydroxy-6-methoxyflavone.     

Bioactive flavones of Sida cordifolia

Two new flavones: 5,7-dihydroxy-3-isoprenyl flavone (1) and 5-hydroxy-3-isoprenyl flavone (2), along with two known compounds β-sitosterol and stigmasterol have been isolated from the chloroform extract of Sida cordifolia. Their structures were established on the basis of spectroscopic analysis. Flavones were tested for their analgesic and anti-inflammatory activity.     

Methylenedioxy- and methoxyflavones from Melicope coodeana syn. Euodia simplex

Three new natural products, 3,8-dimethoxy-5,7-dihydroxy-3′,4′-methylenedioxyflavone, 3,6,8-trimethoxy-5,7-dihydroxy-3′,4′-methylenedioxyflavone and 3,6,8,3′,4′-pentamethoxy-5,7-dihydroxyflavone were isolated from Melicope coodeana syn. Euodia simplex (Rutaceae) along with 3,6,3′-trimethoxy-5,7,4′-trihydroxyflavone and 3,3′-dimethoxy-5,7,4′-trihydroxyflavone. The structural assignments are based on ¹H and ¹³C NMR data, including discussion of the chemical shifts of C-2 in 3,5-dihydroxy- and 3-methoxy-5-hydroxyflavones. The presence of highly methoxylated and methylenedioxyflavones is characteristic of the genus Melicope, and the present findings support the recent transfer of Euodia simplex to Melicope.     

(2S)-Prenylflavanones and taraxerane triterpenoids from Mallotus mollissimus

Three prenylflavanones, (2S)-5,7-dihydroxy-4′-methoxy-8-(3″,3″-dimethylallyl)flavanone (3), (2S)-5,4′-dihydroxy-7-methoxy-6-(3″,3″-dimethylallyl)flavanone (6), 8-prenylnaringenin (11), and a new epimeric pair (2″S/2″R)-(2S)-5,7-dihydroxy-4′-methoxy-6-(2″-hydroxy-3″-methylbut-3″-enyl)flavanones (4a/4b) were isolated together with taraxerone, taraxerol, epitaraxerol, β-sitosterol, oleanolic acid, 1-O-docosanoyl glycerol, apigenin, and apigenin 7-O-β-D-glucopyranoside from the MeOH extract of the leaves of Mallotus mollissimus. The structures of the isolated compounds were determined on the basis of 1D/2D NMR and HR-MS spectroscopic data; the 2S configuration of the prenylflavanones 3, 4, and 6 was deduced from CD spectroscopic data. The presence of three taraxerane triterpenoids reinforces the inclusion of M. mollissimus (syn. Croton mollissimus) in Mallotus genus. Among species of Mallotus the occurrence of the (2S)-prenylflavanones 3, 4, and 6 is confined to M. mollissimus.     

A combined radiogas chromatograph/mass spectrometer detects intermediates in mycophenollc acid biosynthesis

The fusion of a gas-flow proportional counter to a combined gas chromatograph/mass spectrometer is described. Provided components of a tissue extract are volatile in their own right, or can be rendered so by derivatization, the combined unit can separate them, identify each, and provide assays of mass and radioactivity. The counting module has an efficiency of circa 65% for ¹⁴C. To demonstrate the use and versatility of the radiogas chromatograph/mass spectrometer, three biosynthetic intermediates between acetate and mycophenolic acid were identified in extracts of Penicillium brevicompactum. The three substances, 4,6-dihydroxy-2,3-dimethylbenzoic acid; 5,7-dihydroxy-4-methylphthalide, and 6-farnesyl-5,7-dihydroxy-4-methylphthalide, had been implicated previously in the biosynthetic pathway by direct feeding and swamping experiments. A tentative structure for a fourth and previously unencountered intermediate is proposed.     

Homoisoflavonoids and stilbenes from the bulbs of Scilla nervosa subsp. rigidifolia

Thirteen homoisoflavonoids, nine of which are new: 3-(4-methoxybenzyl)-5,7-dimethoxychroman-4-one, 3-(4-hydroxy-3-methoxybenzyl)-5-hydroxy-7-methoxychroman-4-one, 3-(4-methoxybenzylidene)-5,7-dihydroxy-6-methoxychroman-4-one, 3-(4-hydroxybenzylidene)-5-hydroxy-7-methoxychroman-4-one, 3-(4-hydroxy-3-methoxybenzyl)-5-hydroxy-6,7-dimethoxychroman-4-one, 3-(3,4-dimethoxybenzyl)-5,7-dihydroxychroman-4-one, 3-(4-methoxybenzyl)-6-hydroxy-5,7-dimethoxychroman-4-one, 3-(4-hydroxybenzyl)-5,6,7-trimethoxychroman-4-one and 3-(4-methoxybenzyl)-8-hydroxy-5,7-dimethoxychroman-4-one, were isolated from the bulbs of Scilla nervosa together with four known ones and three known stilbene derivatives. The structures of these secondary metabolites were characterized by spectroscopic means and by comparison with published information for known compounds.     

Phenylcoumarins from Ochrocarpus Siamensis

Two new phenylcoumarins, 6-butyryl-5-hydroxy-4-phenylseselin and 6-butyryl-5,7-dihydroxy-8-(3,3dimethylallyl)-4-phenyleoumarin, were isolated from the flowers of Ochrocarpus siamensis.