Fenilpropanóides e outros constituintes bioativos de Nectandra megapotamica

From the trunk bark of Nectandra megapotamica (Lauraceae) four phenylpropanoids, elemicin, isoelemicin, (±)-erythro-1-(3,4,5-trimethoxyphenyl)-1,2-propanediol and (±)-threo-1-(3,4,5-trimetoxyphenyl)-1,2-propanediol have been isolated, in addition to 3,4,5-trimethoxybenzoic acid, (-)-epicatechin and trans-1(10)-epoxy-4(15)-caryophyllene. The diastereoisomeric erythro- and threo- phenylpropanoids are being reported for the first time in a plant taxon as well as the occurrence of the other compounds in Nectandra. The structures of the isolated compounds have been established on the basis of 1D and 2D NMR spectroscopic techniques. Their in vitro antifungal activities against standard strains of Candida albicans, C. krusei, C. tropicalis and Cryptococcus neoformans and antioxidant properties were also evaluated in this work.

Alcaloides iboga de Peschiera affinis (Apocynaceae) - Atribuição inequívoca dos deslocamentos químicos dos átomos de hidrogênio e carbono: atividade antioxidante

Six known alkaloids iboga type and the triterpen α- and β-amyrin acetate were isolated from the roots and stems of Peschiera affinis. Their structures were characterized on the basis of spectral data mainly NMR and mass spectra. 1D and 2D NMR spectra were also used to unequivocal ¹H and 13C chemical shift assignments of alkaloids. The ethanolic extract of roots, alkaloidic and no-alkaloidic fractions and iso-voacristine hydroxyindolenine and voacangine were evaluated for their antioxidative properties using an autographic assay based on β-carotene bleaching on TLC plates, and also spectrophotometric detection by reduction of the stable DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical.

Abietatrienes diterpenoids from Sagittaria montevidensis SSP Montevidensis

The antimicrobial properties of the hexane, hexane/EtOAc and methanol fractions of the fresh petioles of Sagittaria montevidensis ssp montevidensis (Alismataceae) were evaluated against fungi and Gram-negative and Gram-positive bacteria. A new abietatriene-type diterpenoid, 3β,7α-dihydroxi-abieta-8,11,13-triene and the known 3β-hydroxy-abieta-8,11,13-trien-7-one were isolated from the most active fraction tested and the structures of these compounds were elucidated by data including IR, EIMS, and 1D and 2D NMR spectra.

Estudo químico de uma amostra de própolis verde de Passa Quatro, Minas Gerais, Brasil

The phytochemical investigation of a sample of propolis from Passa Quatro-Minas Gerais State, Brazil, where nine constituents were isolated: a mixture of α- and β-amyrin, lupeol, a mixture of flavonols ramnocitrin and eupalitin, acacetin, 3-prenyl-4-hydroxycinnamic acid, 3,5-diprenyl-4-hydroxycinnamic acid the new compound, the (E)-3-[4-(3-phenylpropanoiloxy)]-3,5-diprenil-cinnamic acid. The structures of the isolated compounds were characterized by 1D- and 2D-NMR experiments, MS and IR spectrometry, and comparison with data described in the literature.

Bromopyrrole alkaloids from the caribbean sponge Agelas cerebrum

Bioguided fractionation of Agelas cerebrum crude extract resulted in isolation of four bromopyrrole and four bromopyrrole aminoimidazole alkaloids, identified as 5-bromopyrrole-2-carboxylic acid (1), 4-bromopyrrole-2-carboxylic acid (2), 3,4-bromopyrrole-2-carboxylic acid (3), 4,5-bromopyrrole-2-carboxylic acid (4), oroidin (5), bromoageliferin (6), dibromoageliferin (7) and dibromosceptrin (8) on the basis of spectroscopic data analyses (UV, IR, HRMS, 1D and 2D NMR) and comparison with literature data. This is the first report of compounds 2 and 3 in a marine sponge belonging to the Agelas genus and the first evidence of the presence of 1 from a natural source.

Constituintes químicos e atividade Leishmanicida de Gustavia elliptica (Lecythidaceae)

The phytochemical investigation of the stem bark and leaves of G. elliptica provided a mixture of the norisoprenoids blumenol B and 6-epiblumenol B along with the triterpenes friedelin, as the major constituent, friedelanol, ursa-9(11),12-dien-3-ol, a-amyrin, β-amyrin, morentenol, epifriedelanol, as well as the sesquiterpenes trans-caryophyllene, α-humulene, ethyl hydnocarpate and other fatty acid esters. The identification of the compounds was performed on basis of spectrometric methods such as GC-MS, IR, MS and 1D and 2D NMR. Stem bark extracts showed significant leishmanicidal activity against promastigote forms of Leishmania braziliensis, with the best results for the chloroform extract.

Flavonoides e sesquiterpenos de Croton pedicellatus Kunth

The chemical investigation of the ethanolic extract from leaves of Croton pedicellatus yielded the bis-nor-sesquiterpenes blumenol A and blumenol A glucoside, along with the flavonoids: tiliroside, 6"-O-p-coumaroyl-β-galactopyranosyl- kaempferol, 6"-O-p-coumaroyl-β-glucopyranosyl-3"-methoxy- kaempferol, kaempferol, 3-glucopyranosyl-quercetin and alpinumisoflavone, as well as 4-hydroxy-3,5-dimethoxybenzoic acid. The identification of all isolated compounds was performed by spectrometric methods, including HR-ESI-MS, 1D and 2D NMR experiments, and by comparison with previously-described physical and spectral data.

Terpenoides e cumarinas de Jatropha ribifolia (Pohl) Baill

Eight compounds, including terpenoids (jatrophone, hydroxyjatrophone, 6-hydroxycyperene, cabraleadiol monoacetyl, and cabraleadiol) and coumarins (fraxetin, fraxidin, and isofraxidin), were isolated from Jatropha ribifolia (Euphorbiaceae). Their structures were established by 1D and 2D NMR (COSY, HSQC, and HMBC) spectra, HRESIMS and comparison with published data.

Alcaloides isoquinolínicos e investigação das atividades antiplasmódica e antibacteriana de Guatteria citriodora (Annonaceae)

Phytochemical investigations of the stem bark, leaves and twigs of Guatteria citriodora resulted in the isolation of eight alkaloids: liriodenine, lysicamine, O-methylmoschatoline, 3-methoxyoxoputerine, palmatine, 3-methoxyguadiscidine, guattescidine and oxoputerine. The structures of the isolated substances were established by extensive spectroscopic techniques (1D and 2D NMR) and mass spectrometry (MS), as well as by comparison with data reported in the literature. The in vitro antimalarial activity of the alkaloidal fractions of the leaves and twigs against Plasmodium falciparum FCR3 showed significant results, with IC50 = 1.07 and 0.33 mg mL-1, respectively. The alkaloidal fraction of the leaves showed moderate activity against Enterococcus faecalis, with IC50 = 125.0 mg mL-1. Antiplasmodial and antibacterial activities are attributed to alkaloidal constituents.

In vivo transformations of artemisinic acid in Artemisia annua plants

Artemisinic acid labeled with both C-13 and H-2 at the 15-position has been fed to intact plants of Artemisia annua via the cut stem, and its in vivo transformations studied by 1D- and 2D-NMR spectroscopy. Seven labeled metabolites have been isolated, all of which are known as natural products from this species. The transformations of artemisinic acid-as observed both for a group of plants, which was kept alive by hydroponic administration of water and for a group, which was allowed to die by desiccation-closely paralleled those, which have been recently described for its 11,13-dihydro analog, dihydroartemisinic acid. It seems likely therefore that similar mechanisms, involving spontaneous autoxidation of the Delta(4,5) double bond in both artemisinic acid and dihydroartemisinic acid and subsequent rearrangements of the resultant allylic hydroperoxides, may be involved in the biological transformations, which are undergone by both compounds. All of the sesquiterpene metabolites, which were obtained from in vivo transformations of artemisinic acid retained their unsaturation at the 11,13-position, and there was no evidence for conversion into any 11,13-dihydro metabolite, including artemisinin, the antimalarial drug, which is produced by A. annua. This observation led to the proposal of a unified biosynthetic scheme, which accounts for the biogenesis of many of the amorphane and cadinane sesquiterpenes that have been isolated as natural products from A. annua. In this scheme, there is a bifurcation in the biosynthetic pathway starting from amorpha-4,11-diene leading to either artemisinic acid or dihydroartemisinic acid; these two committed precursors are then, respectively, the parents for the two large families of highly oxygenated 11,13-dehydro and 11,13-dihydro sesquiterpene metabolites, which are known from this species. (C) 2007 Elsevier Ltd. All rights reserved.

In vivo transformations of dihydro-epi-deoxyarteannuin B in Artemisia annua plants

[15-(CH3)-C-13-H-2]-dihydro-epi-deoxyarteannuin B (4a) has been fed to intact Artemisia annua plants via the root and three labeled metabolites (17a-19a) have been identified by 1D- and 2D-NMR spectroscopies. The in vivo transformations of 4a in A. annua are proposed to involve enzymatically-mediated processes in addition to possible spontaneous autoxidation. In the hypothetical spontaneous autoxidation pathway, the tri-substituted double bond in 4a appears to have undergone 'ene-type' reaction with oxygen to form an allylic hydroperoxide, which subsequently rearranges to the allylic hydroxyl group in the metabolite 3 alpha-hydroxy-dihydro-epi-deoxyarteannuin B (17a). In the enzymatically-mediated pathways, compound 17a has then been converted to its acetyl derivative, 3 alpha-acetoxy-dihydro-epi-deoxyarteannuin B (18a), while oxidation of 4a at the 'unactivated' 9-position has yielded 9 beta-hydroxy-dihydro-epi-deoxyarteannuin B (19a). Although all of the natural products artemisinin ( 1), arteannuin K ( 7), arteannuin L ( 8), and arteannuin M ( 9) have been suggested previously as hypothetical metabolites from dihydro-epi-deoxyarteannuin B in A. annua, none were isolated in labeled form in this study. It is argued that the nature of the transformations undergone by compound 4a are more consistent with a degradative metabolism, designed to eliminate this compound from the plant, rather than with a role as a late precursor in the biosynthesis of artemisinin or other natural products from A. annua. (C) 2007 Elsevier Ltd. All rights reserved.

A ruthenium(II) complex stabilized by a highly fluorinated PCP pincer ligand

A novel Ru(II) complex containing an electron-poor, highly fluorinated PCPArF pincer ligand has been synthesized in good yield via a transcyclometalation reaction. The complex has been fully characterized by elemental analysis, 1D and 2D NMR techniques, LTV-vis spectroscopy, and cyclic voltammetry. Single-crystal X-ray structural analysis and DFT calculations were performed. The structural features and electronic properties of the remarkably stable PCPArF-Ru(II) complex 4 have been investigated and show unanticipated differences compared to its protio analogue.

C-glycosyl flavones from Peperomia blanda

The methanol extract from aerial parts of the Peperomia blanda (Piperaceae) yielded two C-glycosyl-flavones. Their structures were elucidated on the basis of extensive spectroscopic analysis, including 1D and 2D NMR, chemical transformation and comparison with the related known compounds. The structure of the new flavonoids were established as 4`-methoxy-vitexin 7-O-beta-D-xylopyranoside (1) (7-O-beta-D-xylopyranosyl-8-C-beta-D-glucopyranosyl-4`-methoxy-apigenin) and vicenin-2 (2). The antioxidant activity of both compounds was investigated using the DPPH assay. Both compounds showed only modest activity, with IC50 values of 357.2 mu M for 1, and 90.5 mu M for 2. (C) 2008 Elsevier B.V. All rights reserved.

Cytotoxic Clerodane Diterpenoids from Casearia obliqua

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antibacterial activity of labdane diterpenoids from Stemodia foliosa

As part of a continuing interest in exploring the chemistry of Brazilian medicinal plants, three new labdane diterpenoids, 6 alpha-acetoxymanoyl oxide (1), 6 alpha-malonyloxymanoyl oxide (2), and 6 alpha-malonyloxy-n-butyl ester manoyl oxide (3), together with the known betulinic acid, lupeol, sitosterol, and stigmasterol, were isolated from the aerial parts of Stemodia foliosa. The structures of 1-3 were established on the basis of interpretation of spectroscopic data, including HRESIMS, and 1D and 2D NMR techniques. All compounds were tested against a bacteria panel consisting of Staphylococcus aureus, Bacillus cereus, B. subtilis, B. anthracis, Micrococcus luteus, Mycobacterium smegmatis, and M. phlei. Compound 2 showed, moderate activity against these strains, with MIC values in the range 7-20 mu g/mL.