Phenolic plant growth inhibitors from the flowers of Cucurbita pepo

Eleven compounds isolated from the growth inhibiting active fraction of male flowers of Cucurbita pepo, were identified as p-hydroxybenzaldehyde, anisyl alcohol, p-hydroxybenzyl methyl ether, p-hydroxybenzyl alcohol, veratryl alcohol, isovanillyl alcohol, p-coumaric acid, phloretic acid, benzyl-β-d-glucoside, 4-methoxybenzyl-β-d-glucoside and 3, 4-dimethoxybenzyl-β-d-glucoside. Each compound was assayed for growth inhibiting activity using lettuce seedlings; three showed strong activity, whereas the glucosides were inactive.     

Myricetin and quercetin methyl ethers from Haplopappus integerrimus var. Punctatus

Nine flavonoids including two new myricetin derivatives, myricetin 3′,4′-dimethyl ether and myricetin 3,3′, 4′-trimethyl ether, were obtained from Haplopappus integerrimus var. punctatus. The known compounds are quercetin 7,3′-dimethyl ether, querectin 3,3′-dimethyl ether, isorhamnetin, quercetin 3,7-dimethyl ether, quercetin 3-methyl ether, quercetin and quercetin 3-β-d-glucoside.     

The structures of amentoflavone glycosides isolated from Psilotum nudum

On the basis of new spectroscopic evidence, structures are proposed for three amentoflavone glycosides and an apigenin di-C-glycoside previously isolated from Psilotum nudum. The major glycoside is identified as the 7,4′,4′“-tri-O-β-D-glucopyranoside, minor glycosides as the 4′,4′“-di-O-β-D-glucopyranoside and 7,4′“-di-O-β-D-glucopyranoside, and the apigenin di-C-glycoside as vicenin-2. The amentoflavone glucosides are all new natural products.     

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.     

Flavonoid glycosides of the roots of Glycyrrhiza uralensis

The structure of a flavanone glycoside from the roots of Glycyrrhiza uralensis has been confirmed as 4′-O-[β-d-apio-d-furanosyl-(1 → 2)-β-d-glucopyranosyl]liquiritigenin. In addition, two known flavonoid glucosides, ononin (a minor component) and liquiritin (a major component), were isolated from the same extract.     

Two new xanthone glycosides from Tripterospermum lanceolatum

Oleanolic acid, mangiferin, and two new xanthone glucosides, named lanceoside (1,8-dihydroxy-3,7- dimethoxyxanthone- 4-O-β-d-glucoside) and lancerin (C-4-β-d-glucosyl-1,3,7-trihydroxyxanthone), respectively, were isolated from the aerial parts of Tripterospermum lanceolatum.     

Isopongaglabol and 6-methoxyisopongaglabol,two new hydroxyfuranoflavones from Pongamia glabra

Isopongaglabol and 6-methoxyisopongaglabol, two new hydroxyfuranoflavones, together with two furanoflavones 5-methoxyfurano(8,7-4″,5″)flavone and 5-methoxy-3′,4′-methylenedioxyfurano(8,7-4″,5″)flavone, two simple flavones, desmethoxykanugin and fisetin tetramethyl ether, a chromenoflavanone, ovalichromene B, two triterpenes, cycloart-23-ene-3β,25-diol and friedelin, and β-sitosterol-β-d-glucoside were isolated from the petrol and CHCl₃ extracts of the flowers of Pongamia glabra. The structures of isopongaglabol and 6-methoxyisopongaglabol have been established as 4′-hydroxyfurano(8,7-4″,5″)flavone and 4′-hydroxy-6-methoxyfurano(8,7-4″,5″)flavone, respectively, on the basis of the spectral evidence and they have been confirmed by synthesis.     

Steroidal saponins of Asparagus adscendens

From the methanol extract of the fruits of Asparagus adscendens sitosterol-β-d-glucoside, two spirostanol glycosides (asparanin A and B) and two furostanol glycosides (asparoside A and B) were isolated and characterized as 3-O-[β-d-glucopyranosyl (1→2)-β-d-glucopyranosyl]-(25S)-5β-spirostan-3β-ol, 3-O-{[β-d-glucopyranosyl(1→2)][α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranosyl}-(25S)-5β-spirostan-3β-ol,3-O-{[β-d-glucopyranosyl(1→2)][α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranosyl|} -26-O-(β- d-glucopyranosyl)-22α-methoxy-(25S)-5β-furostan-3β,26-diol and 3-O-{[β-d-glucopyranosyl(1→2)][α-l-rhamnopyranosyl(1→4)]-β-d-glucopyranosyl}-26-O-(β-d-glucopyranosyl)- 25S)-5β-furostan-3β,22α, 26-triol, respectively.     

Guaianolides from Saussurea affinis

Cynaropicrin, 11βH-11,13-dihydrodesacylcynaropicrin, aguerins A and B, isoamberboin and the new guaianolides saussureolide and 11βH-11,13-dihydrodesacylcynaropicrin 8-β-d-glucoside were isolated from Saussurea affinis.     

Isolation and purification of flavonoid glucosides from Radix Astragali by high-speed counter-current chromatography

High-speed counter-current chromatography methods, combined with resin chromatography were applied to the separation and purification of flavonoid glycosides from the Chinese medicinal herb, Radix Astragali. Five flavonoid glycosides, namely calycosin-7-O-β-d-glucoside, ononin, (6aR, 11aR)-9,10-dimethoxypterocarpan-3-O-β-d-glucoside, (3R)-2′-hydroxy-3′,4′-dimethoxyisoflavan-7-O-β-d-glucoside and calycosin-7-O-β-d-glucoside-6′′-O-acetate, were obtained. Among them, calycosin-7-O-β-d-glucoside-6′′-O-acetate was preparatively separated from Radix Astragali for the first time. Their structures were identified by ESI–MS, ¹H NMR, ¹³C NMR, and 2D NMR.     

Bufadienolides and phytoecdystones from the rhizomes of Helleborus thibetanus (Ranunculaceae)

Two new bufadienolide glycosides with an A/B trans ring structure, 14β,16β-dihydroxy-3β-(β-d-glucopyranosyloxy)-5α-bufa-20,22-dienolide (1), and 14β,16β-dihydroxy-3β-[β-d-glucopyranosyl-(1→4)-(β-d-glucopyranosyloxy)]-5α-bufa-20,22-dienolide (2), two known ecdysteroids (polypodine B and 20-hydroxyecdysone) (3-4), and six known bufadienolide and its glycosides with 5β-OH (hellebrigenin, 16β-hydroxyhellebrigenin-3-O-α-l-rhamnoside, hellebrigenin 3-O-β-d-glucoside, hellebrin, 16β-hydroxyhellebrigenin-3-O-β-d-glucoside, and deglucohellebrin) (5-10) were isolated from the rhizomes of Helleborus thibetanus. The structures of compounds 1 and 2 were elucidated using various spectroscopic methods. All compounds were reported for the first time from the title plant and their chemotaxonomic significance for the genus Helleborus was discussed.     

Flavone 5-O-glucosides from Daphne sericea

The aerial parts of Daphne sericea yielded two new flavonoids, luteolin 7-methyl ether 5-β-d-glucoside and luteolin 7,3′-dimethyl ether 5-β-d-glucoside, as well as luteolin 7-methyl ether, isovitexin, apigenin and its 7-β-d-glucoside.     

Catabolism of flavonol glucosides in plant cell suspension cultures

Catabolism of flavonol glucosides was investigated in plant cell suspension cultures using kaempferol 3-O-β-d-glucoside and kaempferol 7-O-β-d-glucoside labelled with ¹⁴C either in the glucose or in the flavonol moiety. Catabolic rates of glucosides were compared with those of free glucose and kaempferol. All substrates were degraded efficiently by cell cultures of mungbean, soybean, garbanzo bean and parsley. Based on ¹⁴CO₂-formation, glucose from position 3 of kaempferol is 3–5 times more rapidly metabolized than that from position 7. The flavonol nucleus from both isomers is, however, oxidized to the same extent with a considerable portion of the flavonol being incorporated into insoluble polymeric cell material.     

New sweet diterpene glucosides from Stevia rebaudiana

From the leaves of Stevia rebaudiana, two new sweet glucosides, rebaudiosides A and B, were isolated besides the known glucosides, stevioside and steviolbioside. On the basis of IR, MS, ¹H and ¹³C NMR as well as chemical evidences, the structure of rebaudioside B was assigned as 13-O-[β-glucosyl(1-2)-β-glucosyl(1-3)]-β-glucosyl-steviol and rebaudioside A was formulated as its β-glucosyl ester.     

Purification and some properties of steryl β-d-glucoside hydrolase from Sinapis alba seedlings

Homogenates of 7-day-old S. alba seedlings hydrolysed cholesteryl[4-H¹⁴C] β-d-glucoside or sitosteryl β-d-glucoside-[6-³H]. Activity was located predominantly in the cell membrane structures sedimenting at 1000–15 000 g and was solubilized by acetone treatment. Partially purified enzyme preparation, with an about 1500 times higher specific activity with respect to the crude homogenate, was obtained by repeated acetone precipitation and subsequent chromatography on DEAE-Sephadex and Sephadex G-100. During this procedure a considerable separation from other enzymes with β-glucosidase activity was achieved. The enzyme had MW 65 000 daltons, pH optimum at 5.2–5.6. Two observations suggested that the enzyme was a specific steryl β-d-glucoside hydrolase. Firstly, there was no substrate competition between steryl glucosides and several other β-d-glucosides. Secondly, enzyme activity wasstrongly inhibited by low concentrations of various 3β-OH sterols with a planar ring system and an intact side chain.     

Studies on cellulolytic enzymes I: The use of 3,4-dinitrophenyl glycosides as substrates

The syntheses of 3,4-dinitrophenyl β-d-glucoside, β-cellobioside, β-cellotrioside, and β-cellotetraoside and their use to monitor the purification of two enzymes from a crude commercial cellulase preparation from Trichoderma viride are described. The enzymes isolated are an endo-β-1,4-d-glucan glucanohydrolase (EI) of molecular weight ca. 12 000 which catalysed the release of 3,4-dinitrophenol from 3,4-dinitrophenol-β-cellotetraoside, and an enzyme of molecular weight about 76 000 which catalysed the hydrolysis of 3,4-dinitrophenyl β-d-glucoside (EII) and is probably a cellobiase or exo-β-1,4-d-glucan glucohydrolase. Kinetic parameters are reported for the hydrolyses of 3,4-dinitrophenyl β-cellobioside, β-cellotrioside, and β-cellotetraoside catalysed by enzyme EI. In the presence of cellotriose, cellotetraose, or cellopentaose 3,4-dinitrophenyl β-d-glucoside underwent induced hydrolyses by EI. Similar but faster induced hydrolyses were shown by 3,4-dinitrophenyl β-d-xyloside and 3,4-dinitrophenyl β-d-6-deoxyglucoside; 3,4-dinitrophenyl 6-chloro-6-deoxy-β-d-glucoside and 3,4-dinitrophenyl 6-O-methyl-β-d-glucoside underwent slower induced hydrolyses than the glucoside. p-Nitrophenyl β-d-glucoside also underwent an induced hydrolysis in the presence of cellopentaose and the enzyme EI, but p-nitrophenyl 2-deoxy-β-d-glucoside did not. These results are discussed and compared with the results obtained previously on induced hydrolyses found with lysozyme. Kinetic parameters are reported for the hydrolysis of 3,4-dinitrophenyl and p-nitrophenyl β-d-glucosides catalysed by the enzyme EII. 3,4-Dinitrophenyl 6-deoxy-β-d-glucoside, β-d-xyloside, 6-chloro-6-deoxy-β-d-glucoside, 6-O-methyl-β-d-glucoside and p-nitrophenyl-β-d-galactopyranoside and 2-deoxy-β-d-glucopyranoside were hydrolysed 10² to 10³ times slower by EII than the corresponding glucosides, but 3,4-dinitrophenyl 2-acetamido-2-deoxy-β-d-glucoside was only hydrolysed about 25 times slower than 3,4-dinitrophenyl β-d-glucoside. The significance of these results is discussed. EII catalysed the release of 3,4-dinitrophenol from 3,4-dinitrophenyl β-cellobioside, β-cellobioside, and β-cellotetraoside, but these reactions showed induction periods which are consistent with stepwise removal of glucose residues from the oligosaccharide chains before release of the phenol.     

Antiplasmodial and other constituents from four Indonesian Garcinia spp.

Phytochemical investigations of four Garcinia spp. from Indonesia, i.e. Garcinia griffithii T. Anderson, Garcinia celebica L., Garcinia cornea L. and Garcinia cymosa K. Schum (Clusiaceae), have resulted in the isolation of a xanthone, 1,5-dihydroxy-3,6-dimethoxy-2,7-diprenylxanthone, 1,7-dihydroxyxanthone, isoxanthochymol, β-sitosterol-3-O-β-d-glucoside and stigmasterol-3-O-β-d-glucoside from the stem bark of G. griffithii; friedelin and 3β-hydroxy-23-oxo-9,16-lanostadien-26-oic acid or garcihombronane D from leaves of G. celebica; 23-hydroxy-3-oxo-cycloart-24-en-26-oic acid and epicatechin from stem bark of G. cornea; (±)-morelloflavone, morelloflavone-7-O-β-d-glucoside or fukugiside, the triterpene 3β-hydroxy-5-glutinen-28-oic acid and canophyllol from stem bark of G. cymosa. The xanthone and garcihombronane D displayed a selective activity against Plasmodium falciparum; isoxanthochymol and the triterpene β-hydroxy-5-glutinen-28-oic acid a broad but non-selective antiprotozoal activity.     

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.     

Absolute configuration of tetraphyllin b,a cyanoglucoside from tetrapathaea tetrandra

The absolute configuration of tetraphyllin B, the major cyanoglucoside from immature fruit of Tetrapathaea tetrandra, was determined by X-ray diffraction and enzymic hydrolysis to be (1S,4S)1-cyano-4-hydroxypent-2-en-β-d-glucoside.     

Polyphenols of Eucalyptus sideroxylon wood

Twenty-three major components were detected in the methanol extractives of the heartwood of Eucalyptus sideroxylon. The components identified include resveratrol, resveratrol-β-glucoside, 3,3′-di- and 3,3′,4-tri-o-methylellagic acids and their glucosides. The 3,3′-di-o-methylellagic acid 4′-glucoside isolated had properties significantly different from those previously reported for this compound. Also present were gailic acid, catechin, ellagic acid, an unidentified stilbene, the ellagitannins D-6 and D-13, polymerized leucocyanidin and an oily material. The sapwood contained gailic acid, small amounts of ellagitannins and ellagic acids and traces of other components. The heartwood extractives of related eucalypt species were also examined.