Flavonoid constituents of Ephedra alata

Two new flavonol glucosides have been identified in Ephedra alata, namely, herbacetin 8-methyl ether 3-O- glucoside-7-O-rutinoside and herbacetin 7-O-(6″-quinylglucoside). The known flavonoids vicenin II, lucenin III, kaempferol 3-rhamnoside, quercetin 3-rhamnoside and herbacetin 7-glucoside were also found. The structure of the isolated compounds was determined mostly by FABMS and ¹H NMR spectroscopy. The final structure of the new compounds and of herbacetin 7-glucoside was confirmed by ¹³C NMR spectroscopy.     

Isomollupentin-O-glucosides from Cerastium arvense

Eight C-glycosylflavone O-glycosides including three new compounds: isomollupentin 7-O-glucoside, isomollupentin 4′-O-glucoside and isomollupentin 2″-O-glucoside have been isolated from the leaves and flowers of Cerastium arvense. The 27 C-glycosylflavones identified in this plant are tabulated.     

New C-glycosylflavones from Cerastium arvense

Three C-glycosylflavones isolated from Cerastium arvense have been identified as 6-C-xylosyl-apigenin (cerarvensin), its 7-O-glucoside and isovitexin 7,2″-di-O-glucoside.     

Flavonoids of Helichrysum chasmolycicum and its antioxidant and antimicrobial activities

From the aerial parts of Helichrysum chasmolycicum P.H Davis, which is an endemic species in Turkey, the flavonoids apigenin, luteolin, kaempferol, 3,5-dihydroxy-6,7,8-trimethoxyflavone, 3,5-dihydroxy-6,7,8,4′-tetramethoxyflavone, apigenin 7-O-glucoside, apigenin 4′-O-glucoside, luteolin 4′-O-glucoside, luteolin 4′,7-O-diglucoside, kaempferol 3-O-glucoside, kaempferol 7-O-glucoside and quercetin 3-O-glucoside were isolated. The methanol extract of the aerial parts of H. chasmolycicum showed antioxidant activity by DPPH method (IC₅₀ 0.92 mg/mL). Antimicrobial activity test was performed on the B, D, E extracts and also 3,5-dihydroxy-6,7,8-trimethoxyflavone and kaempferol 3-O-glucoside which were the major flavonoid compounds obtained from aerial parts of H. chasmolycicum by microbroth dilutions technique. The E (ethanol-ethyl acetate) extract showed moderate antimicrobial activity against Pseudomonas aeruginosa, B (petroleum ether-60% ethanol-chloroform) extract and 3,5-dihydroxy-6,7,8-trimethoxyflavone showed moderate antifungal activity against Candida albicans.     

C-glycosylflavones from Oryza sativa

Eight flavone C-glycosides isolated from rice plant were found to act as probing stimulants for planthoppers. They have been identified as the known compounds schaftoside, neoschaftoside, carlinoside, isoorientin 2″-glucoside and the new constituents neocarlinoside (6-C-β-D-glucopyranosyl-8-C-β-L-arabinopyranosylluteolin), isoscoparin 2″-glucoside (chrysoeriol 6-C-β-D-(2-O-β-D-glucopyranosyl)glucopyranoside) and its 6?-p-coumaric and ferulic acid esters.     

Flavone C-glycosides from Coronilla varia

One new and 5 known flavone C-glycosides were isolated from leaves and stems of Coronilla varia. The new compound was shown to be isoorientin 2″-O-rhamnoside. The known compounds were isovitexin, isoorientin, isovitexin 4′-O-glucoside, isoorientin 4′-O-glucoside, and isoorientin 7-O-glucoside.     

Biologically-active flavonoids from Gossypium arboreum

A new flavonol glycoside, gossypetin 8-O-rhamnoside, was isolated from flower petals of Gossypium arboreum along with quercetin 7-O-glucoside, quercetin 3-O-glucoside and quercetin 3′-O-glucoside. These compounds showed antibacterial activity against Pseudomonas maltophilia and Enterobacter cloacae.     

Flavonol tetraglycosides from the leaves of Prunus cerasus and P. Avium

Four new flavonol glycosides have been identified from fresh leaves and fruits of sweet and sour cherries (Prunus avium and P. cerasus) as minor flavonoids: quercetin 3-O-rutinosyl-7,3′-O-bisglucoside; two quercetin 3-O-rutinosyl-4′-di-O-glucosides; kaempferol 3-O-rutinosyl-4′-di-O-glucoside.     

The flavonoids of tetragonotheca (compositae)

Fifteen flavonols, five aglycones and ten glucosides were isolated from the four species of Tetragonotheca, T. repanda, T. helianthoides, T. texana and T. ludoviciana. Included among the isolated flavonols are four previously unreported 7-O-glucosides, 6-hydroxykaempferol 7-O-glucoside, 6-hydroxykaempferol 6-methyl ether 7-O-glucoside, quercetagetin 6,3′-dimethyl ether 7-O-glucoside and quercetagetin 3,6-dimethyl ether 7-O-glucoside.     

New 8-hydroxyflavonoids from Solanum section Androceras

Five new 8-hydroxyflavonoids have been identified from leaves of Solanum section Androceras: 8-methoxymyricetin 3,7,4′-trimethyl ether; 8-hydroxymyricetin 3,7,4′-trimethyl ether; 8-hydroxymyricetin 8-O-glucosylxyloside 3,7,4′-trimethyl ether; 8-hydroxychrysoeriol 7-methyl ether; 8-hydroxychrysoeriol 7-O-glucoside.     

Anthocyanins and flavonols from the flowers of Amherstia nobilis endemic to Myanmar

Three anthocyanins (1–3) and eight flavonols (4–11) were isolated from the flowers of Amherstia nobilis endemic to Myanmar. Anthocyanins were identified as cyanidin 3-O-glucoside (1), 3-O-xyloside (2), and peonidin 3-O-glucoside (3). On the other hand, flavonols were identified as isorhamnetin 3-O-glucoside (4), 7-O-glucoside (5), 3,7-di-O-glucoside (6) and 3-O-rutinoside (7), quercetin 3-O-rutinoside (8) and 3-O-glucoside (9), and kaempferol 3-O-rutinoside (10) and 3-O-glucoside (11). Although an anthocyanin, pelargonidin 3-O-pentoside, has been reported from the flowers of A. nobilis, it was not found in this survey. The presence of flavonols in A. nobilis was reported in this survey for the first time. Flavonoid composition of Amherstia was chemotaxonomically compared with those of phylogenetically related genera Cynometra and Brownea.     

HPLC-based methods for the identification of gibberellin conjugates: Metabolism of [3H]gibberellin A4 in seedlings of Phaseolus coccineus

A series of chromatographic and derivatization techniques has been developed for the identification of radiolabelled gibberellin (GA) conjugates. The methods are based on reversed-phase HPLC, gel permeation chromatography, anion-exchange chromatography, enzymatic hydrolysis and transesterification of conjugates, and derivatization of free GAs to methoxycoumaryl esters. The procedures have been used to identify GA₄-glucosyl ester, GA₄-3-O-glucoside, a GA₃₄-O-glucoside and GA₈-2-O-glucoside, in addition to GA₁ and GA₈, as products of [1,2-³H]GA₄ metabolism in shoots of light-grown Phaseolus coccineus seedlings.     

The flavonoids of phragmites australis flowers

The major flavonoid constituents of Phragmites australis flowers are the C-glycosylflavones swertiajaponin, isoswertiajaponin and two new O-glycosides, the 3′-O-gentiobioside and the 3′-O-glucoside of swertiajaponin. Two unusual flavonol glycosides, rhamnetin 3-O-rutinoside and rhamnetin 3-O-glucoside, were also characterized from the same tissue.     

Cytokinin metabolism and the modulation of cytokinin activity in radish

The metabolism of zeatin, N⁶-(Δ²-isopentenyl) adenine, dihydrozeatin, zeatin-O-glucoside and dihydrozeatin-O-glucoside has been studied using derooted radish seedlings. The metabolites were identified by UV and GC/MS. The patterns of metabolism are compared and provide evidence that the O-glucosyl conjugates may be storage forms of the cytokinins.     

Complex anthocyanins from Ipomoea congesta

Six acylated anthocyanins have been isolated from the flowers of Ipomoea congesta R. Brown. One has been previously described as an acylated peonidin derivative. Three others are isomers, derived from peonidin-3-(caffeylsophoroside)-5-glucoside. The fifth was characterised as peonidin-3-(p-coumarylcaffeylsophoroside)-5-glucoside and the last as peonidin-3-(coumarylsophoroside)-5-glucoside. It is noteworthy that the anthocyanins found in this species have the same glycosidic pattern, 3-sophoroside-5-glucoside, as those reported for the cyanidin derivatives in Ipomoea cairica flowers. Acylated anthocyanin occurrence in Tubiflorae order is of chemotaxonomical value.     

Wood polyphenols of Eucalyptus polyanthemos

Sixteen major components have been detected in woody tissues of Eucalyptus polyanthemos. The components identified include 2,3- and 4,6-(hexahydroxydiphenoyl)-glucose, a di-(hexahydroxydiphenoyl)-glucose known as pedunculagin, an ellagitannin which appears to be a cyclic di-(hexahydroxydiphenoyl)-diglucose, 3,4,3′-tri-O-methylellagic acid and its 4′-glucoside, 3,4,3′,4′-tetra-O- and 3,3′-di-O-methylellagic acids. A 3,3′-di-O-methylellagic acid glucoside and 2 gallotannins are possibly present in addition to the unidentified ellagitannin D-13. The distribution of these components in the woody tissues is discussed in relation to heartwood formation. The trimethylellagic acid glucoside was also present in the heartwood of other members of the red-box group of eucalypts.     

Identification de C-glucosides flavoniques dans le genre Gentiana (section coelanthe)

Isoorientin, isovitexin, isoorientin-4′-O-glucoside and isovitexin-4′-O-glucoside have been identified in the leaves and roots of Gentiana punctata L., and in the leaves of G. purpurea L., G. pannonica Scop., G. villarsii Ronn., and G. burseri Lapeyr. Comparison with other gentians is discussed.     

Further studies of flavonols of Clibadium (compositae)

The flavonoids of an additional eight species of Clibadium have been determined. The compounds are derivatives of kaempferol, quercetin and quercetagetin. O-Methylated quercetagetin derivatives were found in several taxa with the possibility that 6-methoxykaempferol may also exist in one collection. Kaempferol and quercetin exist as 3-O-glucosides, galactosides, rhamnosides, rutinosides and diglucosides although not all glycosides occur in each taxon. Quercetagetin derivatives occur as 7-O-glucosides. Observations on these newly investigated species confirm previous work in the genus that three types of flavonoid profiles exist: (1) kaempferol and quercetin 3-glycosides; (2) kaempferol and quercetin 3-glycosides plus quercetagetin 7-glucoside; and (3) kaempferol and quercetin 3-glycosides plus quercetagetin 7-glucoside and O-methylated derivatives of quercetagetin.     

Two anthraquinone glycosides from Cassia marginata roots

From the roots of Cassia marginata, 1,3-dihydroxy-6,8-dimethoxy-2-methyl anthraquinone 3-O-rhamnosyl-(1 → 6)-glucopyranoside and 1,3,5,8-tetrahydroxy-2-methyl anthraquinone 3-O-glucoside have been isolated and their structures elucidated.     

The in vivo incorporation of a flavanone into c-glycosylflavones

C-glycosylation, for the biogenesis of C-glycosylflavones, has been demonstrated to occur at the flavanone level for axenically-cultured Spirodela polyrhiza clone 7003. 4′,5,7-Trihydroxy[2-¹⁴C] flavanone (naringenin) was incorporated in a parallel manner into apigenin 7-O-glucoside and apigenin 8-C-glucoside (vitexin) and into luteolin 7-O-glucoside and luteolin 8-C-glucoside (orientin). In addition the data suggests that the enzyme which oxidizes flavanone (chalcone) to flavone is irreversible under the described experimental conditions.