Prenylated flavonoids from Deguelia hatschbachii and their systematic significance in Deguelia

Chemical investigation of dichloromethane and petrol extracts from the roots of D. hatshbachii A. M. G. Azevedo furnished thirteen compounds from which five are described for the first time and their structures were determined to be 3-(4'-hydroxyphenyl)-5-methoxy-6-( 3,3-dimethylallyl)-2"2"-dimethylchromene-(5",6":8,7)-3-(propyl-2-one)-4H-1-benzo-2,3-dihydropyran-2,4-dione; 6,4'-dihydroxy-3-(3,3-dimethylallyl)-2",2"-dimethylchromene (5",6":5,4)-2-methoxy deoxybenzoin; 6.4'-dihydroxy-3-(3,3-dimethylallyl)-2",2"-dimethylchromene (5",6":5,4)-2-methoxy-8-(propyl-2-one) deoxybenzon; 6-(3,3-dimethylallyl)-2",2"-dimethylchromene (5",6":4.5)-4'-hydroxy-3-methoxy stilbene and 3,5-dimethoxy-4'-hydroxy-4-(3,3-dimethylallyl) stilbene by spectral analysis (UV, IR, MS and ID- and 2D- NMR experiments). The root extracts and some isolated compounds were bioactive, as revealed by bioautography and brine shrimp lethality assays.     

Prenylated anthronoid antioxidants from the stem bark of Harungana madagascariensis

Two new prenylated anthronoids, harunmadagascarins A and B, were isolated from the stem bark of Harungana madagascariensis along with six known compounds including two anthronoids: harunganol B and harungin anthrone, one benzophenone: methyl 3-formyl-2,4-dihydroxy-6-methyl benzoate and three pentacyclic triterpenes: friedelin, lupeol and betulinic acid. Harunmadagascarins A and B were characterized as 8,9-dihydroxy-4,4-bis-(3,3-dimethylallyl)-6-methyl-2,3-(2,2-dimethylpyrano)anthrone and 8,9-dihydroxy-4,4,5-tris-(3,3-dimethylallyl)-6-methyl-2,3-(2,2-dimethylpyrano)anthrone, respectively. The structures of these secondary metabolites were determined by spectroscopic means and comparison with the published data. Methyl 3-formyl-2,4-dihydroxy-6-methyl benzoate was isolated for the first time from a plant. Harunmadagascarins A and B, harunganol B and harungin anthrone exhibited significant antioxidant activity.     

Quinoline alkaloids and cytotoxic lignans from Haplophyllum tuberculatum

Three quinoline alkaloids and two lignan lactones were isolated from Haplophyllum tuberculatum. Physicochemical and spectral evidence established the structures of two of the alkaloids as a new quinoldione, 3-(1′,1′-dimethylallyl)-3-(3″,3″-dimethylallyl)-1,2,3,4-tetrahydro-2,4-quinoldione and the known 4-(3′,3′-dimethylallyloxy)-3-(3″,3″-dimethylallyl)-2(1H)-quinolone. The former was shown to undergo facile [3,3]-sigmatotropic transformation into the latter. The remaining compounds were identified as the known Polygamain, kusunokinin and 1-methyl-2-n-nonyl-4(1H)-quinolone.     

Further phloroglucinol derivatives in the fruits of Mallotus japonicus

Two new rottlerin-like phloroglucinol derivatives were detected from the fruits of Mallotus japonicus and identified as 3-(3,3-dimethylallyl)-5-(3-acetyl-2,4-dihydroxy-5-methyl-6-methoxybenzyl)-phlorobutyrophenone and -phloroisobutyrophenone by spectral studies. 2,6-Dihydroxy-3-methyl-4-methoxyacetophenone was also isolated     

Diprenylated chalcones and other constituents from the twigs of Dorstenia barteri var. subtriangularis

The twigs of Dorstenia barteri var. subtriangularis yielded three diprenylated chalcones: (-)-3-(3,3-dimethylallyl)-5'-(2-hydroxy-3-methylbut-3-enyl)-4,2',4'-trihydroxychalcone, (+)-3-(3,3-dimethylallyl)-4',5'-[2'-(1-hydroxy-1-methylethyl)-dihydrofurano]-4,2'-dihydroxychalcone and 3,4-(6",6"-dimethyldihydropyrano)-4',5'-[2',-(1-hydroxy-1-methylethyl)-dihydrofurano]-2'-hydroxychalcone for which the names bartericins A, B and C, respectively, are proposed. Stipulin, beta-sitosterol and its 3-beta-D-glucopyranosyl derivative were also isolated. The structures of these secondary metabolites were determined on the basis of spectroscopic analysis, especially, NMR spectra in conjunction with 2D experiments, COSY, HMQC and HMBC. The structural relationship of bartericins B and C was further established by the chemical cyclization of one to the other.     

Prenylated flavonoids from Moghania philippinensis

Five prenylated flavonoids, 8-(1,1-dimethylallyl)genistein (1), 5,7,3',4'-tetrahydroxy-2',5'-di(3-methylbut-2-enyl)isoflavone (2), 5,7,3'-trihydroxy-2'-(3-methylbut-2-enyl)-4',5'-(3,3-dimethylpyrano)isoflavone (3), (2R)-5,2',4'-trihydroxy-8,5'-di(3-methylbut-2-enyl)-6,7-(3,3-dimethylpyrano)flavanone (4a) and (2S)-5, 2', 4'-trihydroxy-8,5'-di(3-methylbut-2-enyl)-6,7-(3,3-dimethylpyrano)flavanone (4b), were isolated from the roots of Moghania philippinensis. The structures of these compounds were determined on the basis of spectroscopic and chemical means.     

Identification and biological evaluation of grapefruit oil components as potential novel efflux pump modulators in methicillin-resistant Staphylococcus aureus bacterial strains

Methicillin-resistant Staphylococcus aureus (MRSA) and MSSA strains were treated with: (a) grapefruit oil (GFO) components, isolated by chromatography and characterised by NMR and mass spectroscopy; (b) antimicrobial agents, or (c) a combination of both to evaluate (MIC determination) intrinsic antibacterial activity and to determine whether GFO components could modulate bacterial sensitivity to the anti-bacterial agents. Preliminary data suggested that the grapefruit component 4-[[(E)-5-(3,3-dimethyl-2-oxiranyl)-3-methyl-2-pentenyl]oxy]-7H-furo[3,2-g]chromen-7-one (2) enhances the susceptibility of test MRSA strains to agents, e.g., ethidium bromide and norfloxacin, to which these micro-organisms are normally resistant.     

Prenylated chalcones, flavone and other constituents of the twigs of Dorstenia angusticornis and Dorstenia barteri var. subtriangularis

The twigs of Dorstenia angusticornis and Dorstenia barteri var. subtriangularis yielded 16 compounds. Two novel diprenylated chalcones: 3,5'-di-(2-hydroxy-3-methylbut-3-enyl)-4,2',4'-trihydroxychalcone, 3, 4-(2,2-dimethylpyrano)-3'-(2-hydroxy-3-methylbut-3-enyl)-2',4'-dihydroxychalcone and the known stipulin were isolated from both species. 3-(2-Hydroxy-3-methylbut-3-enyl)-5'-(3,3-dimethylallyl)-4,2',4'-trihydroxychalcone and the known compounds: 4-hydroxylonchocarpin, kanzonol B, bartericins A, B, C and 3'-(2-hydroxy -3-methylbut-3-enyl)-4,2',4'-trihydroxychalcone were isolated from D. barteri while the known compounds: gancaonin Q, paratocarpins C, F, and lupeol were obtained from Dorstenia angusticornis. beta-Sitosterol and its beta-d-glucopyranoside were isolated from both species. Structures of these secondary metabolites were established using spectroscopic analysis, especially, NMR spectra in conjunction with 2D experiments, COSY, HMQC and HMBC.     

Two biflavonoids from Ouratea flava stem bark

In a chemical investigation on the stem bark of Ouratea flava, two biflavonoids: 1-[3-(2,4-dihydroxy-benzoyl)-4,5,6-trihydroxy-2-(4-hydroxy-phenyl)-benzofuran-7-yl] -3-(4-hydroxy-phenyl) -propenone (flavumone A) and 3-(2,4-dihydroxy-benzoyl)-4-hydroxy-2,7-bis-(4-hydroxy-phenyl) -7,8- dihydro-furo[2,3-f]chromen-9-on (flavumone B) were isolated along with five known flavonoids. Their structures were established by various analyses including 2D-NMR spectroscopy.     

Prenylated flavonoids, monoterpenoid furanocoumarins and other constituents from the twigs of Dorstenia elliptica (Moraceae)

A monoprenylated flavan and two monoterpenoid substituted furanocoumarins were isolated from the twigs of Dorstenia elliptica along with 3-(3,3-dimethylallyl)-4,2',4'-trihydroxylchalcone, psoralen, bergapten, O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl)butyl]bergaptol, beta-sitosterol and its beta-D-glucopyranoside. The structure of the flavan was determined as 6(1,1-dimethylallyl)-7,4'-dihydroxylflavan and the monoterpenoid substituted furanocoumarins were assigned as O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl)-3-hydroxybutyl]-bergaptol and O-[2-(5-hydroxy-2,6,6-trimethyl-3-oxo-2H-pyran-2-yl)ethyl]bergaptol, respectively, using spectroscopic analysis, especially, 2D NMR spectra.     

Xanthones from three Garcinia species

From the stem bark of three previously uninvestigated Garcinia species a number of xanthones have been isolated including three that appear to be novel. The novel compounds are characterized as isocowanin (8-geranyl-4-(3,3-dimethylallyl)-7-methoxy-1,3,6-trihydroxyxanthone), isocowanol (8-geranyl-4-(3-hydroxymethyl-3-methylallyl)-7-methoxy-1,3,6-trihydroxyxanthone) and nervosaxanthone (4,8-di(3,3-dimethylallyl)-2-(1,1-dimethylallyl)-1,3,5,6-tetrahydroxyxanthone). The chemotaxonomic significance of oxygenation patterns in these xanthones is briefly discussed.     

Flavanone 8-dimethylallyltransferase in Sophora flavescens cell suspension cultures

Dimethylallyl diphosphate: naringenin 8-dimethylallyltransferase (EC 2.5.1) was characterized. The enzyme was enantiospecific for (-)-(2S)-naringenin and utilized 3,3-dimethylallyl diphosphate as sole prenyl donor. It required Mg2+ (optimum concentration, 10 mM), and has an optimum pH of 9-10. The apparent Km values for 3,3-dimethylallyl diphosphate and naringenin were 120 and 36 microM, respectively. The microsomal fraction prenylated several other flavanones at the C-8 position less effectively as compared with naringenin. Interestingly, when 2'-hydroxynaringenin was used as a prenyl acceptor, the 8-lavandulyl (sophoraflavanone G) and the 6-dimethylallyl derivatives were formed, together with the 8-dimethylallyl derivative, leachianone G. These results suggest that the 2'-hydroxy group of naringenin plays an important role for the formation of a lavandulyl group.     

8-Biarylchromen-4-one inhibitors of the DNA-dependent protein kinase (DNA-PK)

The synthesis and biological evaluation of libraries of 8-biarylchromen-4-ones enabled the elucidation of structure–activity relationships for inhibition of the DNA-dependent protein kinase (DNA-PK), with 8-(3-(thiophen-2-yl)phenyl)chromen-4-one and 8-(3-(thiophen-3-yl)phenyl)chromen-4-one being especially potent inhibitors.     

Isoflavones from Lupinus angustifolius root

Two novel isoflavones, 5,7,2′-trihydroxy-6-(3,3-dimethylallyl)-[6″,6″-dimethylpyrano(2″,3″:4′,3′) ]-isoflavone and 5,2′,4′-trihydroxy-3′-(3,3-dimethylallyl)-[6″,6″-dimethylpyrano(2″,3″:7,6)]isoflavone, have been isolated from the roots of Lupinus angustifolius cv. Uniharvest. Structures were established by analysis of ¹³C NMR and other spectral data, and by chemical conversion of one of the compounds to a coumaronochromone.     

Lactones,flavonoids and benzophenones from Garcinia conrauana and Garcinia mannii

Two novel lactones have been isolated from the stem barks of Garcinia conrauana and G. mannii. The major component of the bark of G. conrauana was identified as 3-(3$\text{,}\text{?}$ 3″-dimethylallyl)-conrauanalactone [4-hydroxy-3-(3″, 3″-dimethylallyl)-6-pentadecylpyran- 2-one] by comparison of spectral data of the isolated compound and two methylethers with that obtained for the previously isolated conrauanalactone. A minor component of the bark of G. mannii was tentatively identified as 3-α-hydroxy-5-(heptadec-8′-enyl)-tetrahydro- furan-2-one on the basis of spectral data from the isolated compound and its monoacetate. The distributions of biflavonoids and related compounds and benzophenones in the stem bark, heartwood, seeds and leaves of the two species are reported.     

Flavonoids from the seeds of Lonchocarpus costaricensis

Seven flavonoids have been isolated from the seeds of Lonchocarpus costaricensis of which four appear to be novel. The new compounds have been identified as the β-hydroxychalcone demethylpraecansone-B and the flavanones 7-(3,3-dimethylallyloxy)-8-(3-hydroxy-3-methyl-trans-but-1-enyl)flavanone, 7-(3,3-dimethylallyloxy)-8-(3,3-dimethylallyl)-5-methoxyflavanone and 8-(3,3-dimethylallyl)-5,7-dimethoxyflavanone.     

Dihydrochalcones, coumarins and alkaloids from Metrodorea nigra

Two novel dihydrochalcones, 2′,3,4′,6′-tetrahydroxy-4-methoxy-3′,5-di-(3,3-dimethylallyl)-dihydrochalcone and 2′,.3,6′-trihydroxy-4-methoxy-5-(3,3-dimethylallyl)-3′,4′-(2″,2″-dimethyldihydropyran)-dihydrochalcone, have been isolated from fresh fruits of Metrodorea nigra. Stems and leaves showed a similar composition and we have isolated common steroids, simple coumarins, several furocoumarins, furoquinoline alkaloids and a furofuran lignan. From stems, we have also isolated the pentacyclic 6-C-monoterpenyl-5,7-dioxycoumarin, deoxybruceol. Structures of the isolated compounds were elucidated on the basis of spectral data.     

New isoflavonoids related to kievitone from Phaseolus vulgaris

The new isoflavonoids 5,7,2′,4′-tetrahydroxy-8-(3,3-dimethylallyl)isoflavone (2,3-dehydrokievitone) and 7,2′,4′-trihydroxy-8-(3,3-dimethylallyl)isoflavanone (5-deoxykievitone) have been isolated from fungus-inoculated Phaseolus vulgaris pod tissue and from the inoculation droplets. A third isoflavonoid was tentatively identified as 1″,2″-dehydrocyclokievitone and appears to be a metabolite of the phytoalexin kievitone.     

Bildung und weiterreaktion von acylvorstufen der hopfenbitterstoffe

Isobutyric acid is incorporated into desoxycohumulone, cohumulone and colupulone and isovaleric acid is incorporated into desoxyhumulone, humulone and lupulone. The compound 1-isobutyryl-3-(3,3-dimethylallyl)-phloroglucinol (CoX) can be considered as an intermediate for the first three components of the hop resins while isovaleryl-3-(3,3-dimethylallyl)-phloroglucinol (X) is an intermediate in the biosynthesis of the parent compounds.     

Fungitoxic dihydrofuranoisoflavones and related compounds in white lupin,Lupinus albus

Chromatographic investigation of a methanolic extract of white lupin roots has revealed the presence of six new dihydrofuranoisoflavones (lupinisoflavones A-F). Three monoprenylated (3,3-dimethylallyl-substituted) isoflavones (wighteone, luteone and licoisoflavone A), two diprenylated isoflavones [6,3′-di(3,3-dimethylallyl)genistein (lupalbigenin) and 6,3′-di(3,3-dimethylallyl)-2′-hydroxygenistein (2′-hydroxylupalbigenin)] and two pyranoisoflavones (parvisoflavone B and licoisoflavone B) have also been isolated from the same source. In addition to genistein, leaf extracts of L. italbus contain 3′-O-methylorobol which is presumed to be the precursor of lupisoflavone [5,7,4′-trihydroxy-3′-methoxy-6-(3,3-dimethylallyl)isoflavone]. Probable biogenetic relationships between the prenylated, and dihydrofurano-and pyrano-substituted isoflavones in roots and leaves of L. albus are briefly discussed.