Phenolic glucosides from Olea europaea subs. africana

Two new lignan glucosides, (+)-1-acetoxypinoresinol 4″-methyl ether 4′-β-d-glucoside and (+)-1-hydroxypinoresinol 4′-β-d-glucoside, together with three known glucosides, (+)-1-acetoxypinoresinol 4′-β-d-glucoside, esculin and oleuropein, were isolated from the bark of Olea europaea subs africana.     

5-Methyl ether flavone glucosides from the leaves of Bruguiera gymnorrhiza

Two new 5-methyl ether flavone glucosides (7,4′,5′-trihydroxy-5,3′-dimethoxyflavone 7-O-β-D-glucopyranoside and 7,4′-dihydroxy-5-methoxyflavone 7-O-β-D-glucopyranoside) were isolated from the leaves of Thai mangrove Bruguiera gymnorrhiza together with 7,3′,4′,5′-tetrahydroxy-5-methoxyflavone, 7,4′,5′-trihydroxy-5,3′-dimethoxyflavone, luteolin 5-methyl ether 7-O-β-D-glucopyranoside, 7,4′-dihydroxy-5,3′-dimethoxyflavone 7-O-β-D-glucopyranoside, quercetin 3-O-β-D-glucopyranoside, rutin, kaempferol 3-O-rutinoside, myricetin 3-O-rutinoside and an aryl-tetralin lignan rhamnoside. The structure of a lignan rhamnoside was found to be related to racemiside, an isolated compound from Cotoneaster racemiflora, and also discussed. Structure determinations were based on analyses of physical and spectroscopic data including 1D- and 2D-NMR.     

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.     

Chemosystematics of taxa from the Leontodon section Oporinia

A chemosystematic study of the subgenus Oporinia of the genus Leontodon (Asteraceae) was performed, using flavonoids and phenolic acids in the flowerheads as diagnostic characters. A total of 44 samples from nine different Oporinia taxa were analyzed. Five luteolin-derivatives (luteolin, luteolin 7-O-β-d-gentiobioside, luteolin 7-O-β-d-glucoside, luteolin 7-O-β-d-glucuronide, and luteolin 4′-O-β-d-glucoside) and four caffeic acid derivatives (caffeoyl tartaric acid, chlorogenic acid, cichoric acid, and 3,5-dicaffeoylquinic acid) were identified in crude extracts by means of HPLC retention times, on-line UV spectra and on-line MS spectra. Quantification of these compounds was performed by HPLC, using quercetin as internal standard. The data obtained were processed by Principal Component Analysis, resulting in the formation of five different clusters. These clusters were taxonomically interpretable and are in good agreement with the morphologically based system of the genus Leontodon.     

Luteolin and daphnetin derivatives in the juncaceae and their systematic significance

During a chemosystematic survey of 38 representative species of the Juncaceae for leaf and stem flavonoids, the 5-methyl ether of luteolin was discovered for the first time in plants. It occurs both free and as the 7-glucoside; its identity was confirmed by synthesis. Flavone sulphates were also found in the family and the 7-glucosidesulphates of luteolin and chrysoeriol were characterised for the first time. 7,3′,4′-Trihydroxyflavone and its 7-glucoside, not previously reported in the monocotyledons, were found in three species. The presence of luteolin 5-methyl ether or its glucoside in 70% of the species surveyed serves to distinguish the Juncaceae from the morphologically related Centrolepidaceae, Restionaceae and Thurniaceae. Flavone C-glycosides, common in grasses and sedges, were found only in Prionium, a genus which on anatomical grounds is anomalous in the Juncaceae. Among other phenolics detected during the survey, the uncommon 7,8-dihydroxycoumarin, daphnetin, was identified in Juncus effusus and its 8-methyl ether in four Luzula species. Taken together, these chemical findings show that the Juncaceae are very distinctive in their phenolic pattern and confirm the correctness of assigning them an isolated position in a separate order, the Juncales. The results indicate that the Juncaceae are chemically specialized, in spite of the facts that the family has been regarded as ancestral to the Cyperaceae and Gramineae and that they have been assigned a low advancement index by Sporne.     

Flavonoids in leaves and inflorescences of australian Cyperus species

A survey of the flavonoids of some 92 species of Australian Cyperus, mainly of subtropical or tropical origin, has confirmed a correlation previously reported in this family between flavonoid pattern and plant geography. The pattern found was similar to that of African and South American Cyperaceae, particularly in the occurrence of the rare marker substance, luteolin 5-methyl ether. Tricin and luteolin are relatively common, in glycosidic form, in the leaves while the flavonol quercetin is infrequent. When present, quercetin occurs either in glycosidic form or free as a methyl ether. The 3-monomethyl and 3, 7-dimethyl ethers of kaempferol and quercetin and the 3, 7, ?-trimethyl ether of quercetin are reported for the first time from the Cyperaceae. The flavonoid pattern of inflorescences is distinct from that of the leaves in that tricin is not detectable and that luteolin 5-methyl ether appears to be replaced by 7, 3′, 4′-trihydroxyflavone. In addition, the aurone aureusidin is more commonly present than in the leaves and is occasionally accompanied by two further aurones. The glycoxanthones mangiferin and isomangiferin occur rarely in all three species examined in the section Haspani, i.e. in C. haspan, C. prolifer and C. tenuispica. In general, however, the flavonoid data do not offer any markers which separate off different sections within the genus; there are, however, some significant correlations between the frequency of the flavonoid classes and subgeneric groupings.     

A flavanone glycoside from seeds of Sapium sebiferum

The isolation and identification of a new glycoside, eriodictyol 5-O-methyl ether 7-O-β-D-xylopyranosyl-β-D-arabinopyranoside, from seeds of Sapium sebiferum is reported.     

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.     

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.     

An N-glycoside and steroids from Aristolochia indica

A phenanthrene derivative, aristololactam N-β-d-glucoside, and the steroids 3β-hydroxy-stigmast-5-en-7-one and 6β-hydroxy-stigmast-4-en-3-one have been isolated from Aristolochia indica.     

Flavonoid chemistry and plant geography in the Cyperaceae

A leaf survey of 59 tropical (43 African, and 16 South American) Cyperaceae showed that in addition to the expected flavonoid constituents, i.e. glycoflavones and tricin derivatives, a representative number of them (33%) contained luteolin 5-methyl ether. An equal sample of temperate Cyperaceae failed to show any species with this substance. Thus it appears that this rare 5-methylated flavone is restricted to tropical members of the family. In four species of the South American genus, Lagenocarpus, 6-hydroxyluteolin 7-glucoside was identified. This is the first report of this 6-hydroxyflavone in the Cyperaceae and in the monocotyledons. A new glycoside of iso-orientin, the 3'-glucuronide, was identified in Rhynchospora eximia. The new data have been collected in a revised summary of the leaf flavonoid pattern of the Cyperaceae and compared with those of the Gramineae and Juncaceae. The discovery of luteolin 5-methyl ether in the Cyperaceae brings it closer in chemical terms to the Juncaceae, from which family this compound was first isolated     

Chemotaxonomic value of flavonoids in Chromolaena congesta (Asteraceae)

The phytochemical investigation on the aerial parts of Chromolaena congesta led to the isolation of nine flavonoids, known in the literature as genkwanin (1) kumatakenin (2) acacetin (3), kaempferol 3-methyl ether (4), apigenin (5), apigenin 5,7-dimethyl ether (6), apigenin 5-methyl ether (7), luteolin (8) and kaempferol (9). The chemical structures were established on the basis of spectral evidence. All the compounds were isolated from this species for the first time. The results from the present study provide further information about the flavonoids as taxonomic marker of the genus Chromolaena, and the chemotaxonomic significance of these compounds were also summarized.     

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.     

3-Hydroxyisoflavanones from the stem bark of Dalbergia melanoxylon: Isolation,antimycobacterial evaluation and molecular docking studies

Two new 3-hydroxyisoflavanones, (S)-3,4′,5-trihydroxy-2′,7-dimethoxy-3′-prenylisoflavanone (trivial name kenusanone F 7-methyl ether) and (S)-3,5-dihydroxy-2′,7-dimethoxy-2″,2″-dimethylpyrano[5″,6″:3′,4′]isoflavanone (trivial name sophoronol-7-methyl ether) along with two known compounds (dalbergin and formononetin) were isolated from the stem bark of Dalbergia melanoxylon. The structures were elucidated using spectroscopic techniques. Kenusanone F 7-methyl ether showed activity against Mycobacterium tuberculosis, whereas both of the new compounds were inactive against the malaria parasite Plasmodium falciparum at 10 μg/ml. Docking studies showed that the new compounds kenusanone F 7-methyl ether and sophoronol-7-methyl ether have high affinity for the M. tuberculosis drug target INHA.     

Two luteolin o-glucuronides from primary leaves of Secale cereale

Two luteolin O-glucuronides have been located exclusively in the photosynthetically active mesophyll of primary leaves of rye (Secale cereale). Their structures have been elucidated as luteolin 7-O-[β-d-glucuronosyl (1 → 2)β-d-glucuronide]-4′-O-β-d-glucuronide and luteolin 7-O-[β-d-glucuronosyl (1 → 2)β-d-glucuronide]. The former glycoside is a new natural compound.     

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.     

Die flavonolglykoside von Equisetum telmateja

Nine kaempferol glycosides, including the hitherto unkown 3-β-d-(6-O-acetylglucoside)-7-β-d-glucoside and 3-β-d-(6-O-acetylglucoside)-7-α-l-rhamnoside, have been isolated from Equisetum telmateja of European origin.     

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.     

6-Hydroxy- and 6-methoxyflavonoids from Neurolaena lobata and N. macrocephala

Twelve flavonoids including one new sulfate were isolated from Neurolaena lobata, and six known flavonoids were obtained from N. macrocephala. The new compound isolated from N. lobata is 6-hydroxykaempferol 3-methyl ether 7-sulfate, and the known flavonoids are 6-hydroxykaempferol 3,7-di-dimethyl ether, 6-hydroxykaempferol, 3-methyl ether 7-glucoside, 6-hydroxykaempferol 7-glucoside, quercetagetin and its 7-glucoside, quercetagetin 3,6- and 3,7-dimethyl ethers, quercetagetin 3-methyl ether 7-glucoside and 7-sulfate, 6-hydroxyluteolin 3′-methyl ether and 6-hydroxyluteolin 7-glucoside. The known flavonoids identified from N. macrocephala are quercetagetin 3,6- and 3, 7-dimethyl ethers, quercetagetin 6-methyl ether 7-glucoside, quercetagetin 3,6-dimethyl ether 7-glucoside, quercetagetin 7-glucoside and quercetagetin 3-methyl ether 7-sulfate.     

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.