Xanthones and flavonoids from Leiothrix curvifolia and Leiothrix flavescens

8-Carboxymethyl-1,6-dihydroxy-3,5-dimethoxyxanthone 8-carboxymethyl-1,5,6-trihydroxy-3-methoxyxanthone and 8-carboxy-methyl-1,3,5,6-tetrahydroxyxanthone were isolated from the capitula of Leiothrix curvifolia and Leiothrix flavescens and characterized by spectroscopic methods, mainly 1D and 2D NMR experiments, as well as by electrospray mass spectrometry. Eight known flavonoids were also isolated and they were identified by 1D and 2D NMR experiments and comparison with literature data. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Bioactive pyrones and flavonoids from Cryptocarya ashersoniana seedlings

The bioassay directed fractionation of the EtOH extract from leaves of Cryptocarya ashersoniana seedlings led to the isolation of two flavonol glucosides: iso-quercitrin and hyperin, which exhibited free radical scavenging activity towards DPPH (IC50 34.4 muM and 32.7 muM, respectively) and were compared to standard compounds rutin (IC50 27.0 muM) and catechin (IC50 41.4 muM). Investigation of extracts from the seedlings roots and stems afforded one antifungal styrylpyrone: goniothalamine, and two dihydropyrones: 6-propyl-5,6-dihydro-2-pyrone and the new 6-[(4'-ethyl-9'-oxabicyclo[3.3.1]non-6'-en-3'-yl)methyl]-5,6-dihydro-2H-pyran-2-one, which had its structure determined by detailed analysis of MS and NMR data, including 2D experiments.

Turbinatine, a potential key intermediate in the biosynthesis of corynanthean-type indole alkaloids

Extraction of the leaves of Chimarrhis turbinata has led to the isolation of turbinatine (1), a new corynanthean-type indole alkaloid, besides four known indole alkaloids, strictosidine, 5alpha-carboxystrictosidine, vallesiachotamine, and isovallesiachotamine. The structural determination of 1 was based on 1D and 2D spectroscopic data. An evaluation of the DNA-damaging activities of the isolates was performed by means of a bioassay using mutant strains of Saccharomyces cerevisiae, which indicated these compounds were weakly active.

Flavonoids and lignans from Virola surinamensis twigs and their in vitro activity against Trypanosoma cruzi

Dichloromethane extracts from twigs of Virola surinamensis (Myristicaceae) showed in vitro trypanosomicidal activity against trypomastigote form of Trypanosoma cruzi. The extract, fractionated by preparative circular chromatography and preparative high-performance liquid chromatography yielded two steroids, two lignans, five flavonoids, and one polyketide. Among the isolated compounds, the lignans presented the highest trypanosomicidal activity.

Use of on-line liquid chromatography-nuclear magnetic resonance spectroscopy for the rapid investigation of flavonoids from Sorocea bomplandii

This paper reports the identification of di- and triglycosylated flavonoids from Sorocea bomplandii (Moraceae) by liquid chromatography coupled on-line to nuclear magnetic resonance (LC-NMR). These glycosylated flavonoids may be used as a taxonomic marker in future work. (C) 2002 Elsevier B.V. B.V All rights reserved.

Flavonoids and isoflavonoids from Gynerium sagittatum

Four flavonoids namely (2R,3R)-2,3-trans-7,4 '-dimethoxydihydroflavonol, (2R,3S,4S)-2,3-trans-3,4-cis-7,4'-dimethoxy-3,4-flavandiol, 6-hydroxy-7,4 '-dimethoxyflavone, 6,7,4 '-trimethoxyflavone, along with the known isoflavonoids ferreirin, dihydrocajanin, dalbergioidin, dihydrobiochanin A and biochanin A and other I I known compounds were isolated from the roots of Gynerium sagittatum. The structural characterization of these compounds was carried out via one- and two-dimensional NMR experiments in combination with ESI-MS. Finally a quantitative analysis of the isoflavones of the methanolic extract was performed by LC-ESI-MS. The high quantity of isoflavonoids found in G. sagittatum makes this plant a good natural source of isoflavonoids. (c) 2007 Elsevier Ltd. All rights reserved.

Neolignans, styrylpyrones and flavonoids from an Aniba species

The trunk wood and barks from an Aniba species contain four esters of benzoic acid with cinnamyl alcohol, five benzofuran neolignans, licarin-A, burchellin, cis-burchellin, burchellin-rearranged and cis-burchellin-rearranged, one tetrahydrofuran neolignan, aristolignin, three bicyclooctane guianin-type neolignans, (7S, 8S, 1'R, 5'R)-4-hydroxy-3,3'-dimethoxy-4',6'-dioxo-8.1', 7.5'-neolignan-Delta: 1,3,5,2',8' and the new (7S, 8S, 1'R, 4'R, 5'S)-4'-hydroxy-3,4,3'-trimethoxy-6'-oxo-8.1', 7.5'-neolignan-Delta: 1,3,5,2',8' and (7S, 8S, 1'R, 4'R, 5'S)-4,4'-dihydroxy-3,3'-dimethoxy-6'-oxo-8.1', 7.5'-neolignan-Delta: 1,3,5,2',8', one new bicyclooctane canellin-type neolignan (7S, 8S, 1'S, 4'R, 5'R, 6'S)-4',6'-dihydroxy-3,4-dimethoxy-3'-oxo-8.1', 7.5'-neolignan-Delta: 1,3,5,8', two styrylpyrones, 4-methoxy-6-(11,12-dimethoxy-trans-styryl)-2-pyrone and 6-(11,12-methylenedioxy-trans-styryl)-4-methoxy-2-pyrone, two styrylpyrone dimers: 4'-methoxy-8-(11,12-dimethoxyphenyl)-7-[6-(4-methoxy-2-pyronyl)-6-(E)-styryl-1'-oxabicyclo[4,2,0]octa-4'-en-2'-one and the new 11,12-dimethoxyphenyl-7,7'-di-[6-(4-methoxy-2-pyronyl)]-cyclobutane and six flavonoids, 3,5-dihydroxy-7,4'-dimethoxyflavone, 5-hydroxy-3,7,4'-trimethoxyflavone, 3,5,4'-trihydroxy-7-methoxyflavone, 2,3-dihydro-5-hydroxy-7,4'-dimethoxyflavone, 2,3-dihydro-3,5-dihydroxy-7-methoxyflavone, 2,3-dihydro-3,5-dihydroxy-7,4'-dimethoxyflavone and a new flavan, 6,7,3',4',5'-pentamethoxyflavan. (C) 1997 Elsevier B.V. Ltd.

GNN is a self-glucosylating protein involved in the initiation step of glycogen biosynthesis in Neurospora crassa

The initiation of glycogen synthesis requires the protein glycogenin, which incorporates glucose residues through a self-glucosylation reaction, and then acts as substrate for chain elongation by glycogen synthase and branching enzyme. Numerous sequences of glycogenin-like proteins are available in the databases but the enzymes from mammalian skeletal muscle and from Saccharomyces cerevisiae are the best characterized. We report the isolation of a cDNA from the fungus Neurospora crassa, which encodes a protein, GNN, which has properties characteristic of glycogenin. The protein is one of the largest glycogenins but shares several conserved domains common to other family members. Recombinant GNN produced in Escherichia coli was able to incorporate glucose in a self-glucosylation reaction, to trans-glucosylate exogenous substrates, and to act as substrate for chain elongation by glycogen synthase. Recombinant protein was sensitive to C-terminal proteolysis, leading to stable species of around 31 kDa, which maintained all functional properties. The role of GNN as an initiator of glycogen metabolism was confirmed by its ability to complement the glycogen deficiency of a S. cerevisiae strain (glg1 glg2) lacking glycogenin and unable to accumulate glycogen. Disruption of the gnn gene of N. crassa by repeat induced point mutation (RIP) resulted in a strain that was unable to synthesize glycogen, even though the glycogen synthase activity was unchanged. Northern blot analysis showed that the gnn gene was induced during vegetative growth and was repressed upon carbon starvation. (C) 2004 Elsevier B.V. All rights reserved.

CHEMICAL SYMPATHECTOMY BLOCKS ANDROGEN BIOSYNTHESIS DURING PREPUBERTY

Twenty-one-day old male Wistar rats were injected subcutaneously with guanethidine (GUA) at doses of 5 and 10 mg kg(-1) day(-1) for 20 days. Animals were sacrificed by decapitation during the prepubertal (41 days of age) and early-pubertal (51 days of age) periods of sexual development. The testes were collected, frozen in liquid N-2 and stored at -70 degrees C until determination of testicular progesterone (P): androstenedione (A) and testosterone (T). Higher levels of P (2.18 +/- 0.24 ng/g. control = 1.24 +/- 0.16 ng/g) associated with decreased levels of androgens (A = 0.26 +/- 0.06 ng/g and T = 2.05 +/- 0.19 ng/g; control = 1.86 +/- 0.76 ng/g and 8.48 +/- 1.16 ng/g, respectively) were observed in 10 mg GUA-treated rats of prepubertal age, while only P levels (3.12 +/- 0.51 ng/g control = 1.73 +/- 0.27 ng/g) were increased in rats of early pubertal age. It is important to note that in 41-day old male rats both 5 and 10 mg were effective in decreasing testicular concentration of testosterone. These results suggest that the sympathetic innervation of the testis is involved in the modulation of androgen biosynthesis, acting through a selective step in the steroid biochemical pathway during the pubertal process and that under the conditions employed the blockage in androgen biosynthesis in the prepubertal stage of sexual maturation is dependent on the dose of GUA.

Flavonoids from Iryanthera sagotiana

Leaves and inflorescences of Iryanthera sagotiana were found to contain three known dihydrochalcones, two flavonol rhamnosides, four flavanonol rhamnosides, one dihydrocoumaric acid, besides the new 3,'3'''-bis-2',4',6'-trihydroxy-4-methoxydihydrochalcone and 4',6'-dihydroxy-4-methoxydihydrochalcone-2'-O-beta-D-glucopyranoside. (C) 1997 Elsevier B.V. Ltd.

Biosynthesis of friedelane and quinonemethide triterpenoids is compartmentalized in Maytenus aquifolium and Salacia campestris

Maytenus aquifolium (Celastraceae) and Salacia campestris (Hippocrateaceae) species accumulate friedelane and quinonemethide triterpenoids in their leaves and root bark, respectively. Enzymatic extracts obtained from leaves displayed cyclase activity with conversion of the substrate oxidosqualene to the triterpenes, 3 beta -friedelanol and friedelin. In addition, administration of (+/-)5-H-3 mevalonolactone in leaves of M. aquifolium seedlings produced radio labelled friedelin in the leaves, twigs and stems, while the root bark accumulated labelled maytenin and pristimerin. These experiments indicated that the triterpenes once biosynthesized in the leaves are translocated to the root bark and further transformed to the antitumoral quinonemethide triterpenoids. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Chemical composition of flavonoids and styrylpyrones and the genetic variability of isozymes in natural populations of Cryptocarya mandioccana Meisner (Lauraceae)

The chemical composition of leaves of 57 trees of Cryptocarya mandioccana from three populations of southeastern Brazil was investigated through HPLC, assaying six flavonoids, seven styrylpyrones, and seven unidentified compounds. From 51 of the former trees, genotypes were obtained from 40 polymorphic loci of 19 isozymes. Cluster analyses of the phytochemical and genetical variation revealed that trees exhibited four chemotypes and five clusters from isozymes, respectively. Discriminant analyses from selected variables of the isozymic and chemical data sets were performed, respectively, in relation to the four chemotypes and the five isozyme clusters. The classification of individuals presented respective error estimates of 9.16% and 13.57%, indicating that the genetic data could explain the clusters from chernotypes and vice versa at acceptable error levels. Linear regressions with Dummy variable showed significant association of locus Skdh-2 with quercetin-3-O-beta-D-glucopyranoside and cryptofolione, indicating that its alleles would be responsible for the chemotype variation between individuals. (c) 2006 Elsevier Ltd. All rights reserved.

Planifolin, a new naphthopyranone dimer and flavonoids from Paepalanthus planifolius

A new naphthopyranone dimer (I) named planifolin was isolated from a methylene chloride extract of the capitula of Paepalanthus planifolius. The structure of 1 has been determined by chemical and spectroscopic means. In addition, a known dihydronaphthopyranone glycoside and seven known flavonoids were isolated from an ethanolic extract of the leaves of P. planifolius.

Dimorphandra mollis: an alternative as a source of flavonoids with antioxidant action

Dimorphandra mollis: An Alternative as a Source of Flavonoids with Antioxidant Action. Dimorphandra molls fruits are rich in flavonoids rutin and quercetin, which are compounds with high antioxidant activity and can be used to prevent diseases caused by free radicals. The aim of this study was to obtain an extract rich in flavonoids from fruits of D. mollis. The extract was analyzed using the methods of determination by spectrophotometry and high performance liquid chromatography. The presence of rutin and quercetin was identified in the extract, which showed a total flavonoids content of 33.71 To. The extract also showed antioxidant activity as scanvanger of DPPH and ABTS radicals. It was possible to conclude that D. mollis fruits are a rich source of flavonoids with antioxidant action.