Aryltetralol and aryltetralone lignans from Holostylis reniformis

Aryltetralol and aryltetralone lignans were isolated from the hexane extracts of the roots of Holostylis reniformis. Their structures were determined by spectroscopic methods and chemical transformations. (c) 2006 Elsevier Ltd. All rights reserved.

8-benzylberbine and N-oxide alkaloids from Aristolochia gigantea

From the ethanol extract of Aristolochia gigantea Mart an 8-benzylberbine-type alkaloid and an N-oxide were isolated together with pinitol and sequoyitol. Structural assignments were based on analysis of spectral data, mainly by 2D NMR spectroscopic techniques. (C) 1997 Elsevier B.V. Ltd.

Diterpene esters of aristolochic acids from Aristolochia pubescens

From the acetone and ethanol extracts of the tubercula of Aristolochia pubescens, two diterpene esters of aristolochic acids were isolated, together with 23 known compounds. The structures of the compounds were determined on the basis of spectroscopic analysis. (C) 2003 Elsevier Ltd. All rights reserved.

Tetrahydroisoquinoline alkaloids and 2-deoxyribonolactones from Aristolochia arcuata

2-Deoxyribonolactones and four tetrahydroisoquinoline alkaloids were isolated from the acetone extract of the leaves of Aristolochia arcuata Mast., together with pinitol, sequoyitol, glycerol, fructose, sucrose, eupomatenoid-7, salsolinol, and 6,7-dihydroxyl,1-dimethyl-1,2,3,4-tetrahydroisoquinoline. Their structures were determined on the basis of spectroscopic methods, mainly using H-1, C-13, N-15, and P-31 NMR. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

Rearranged (4 -> 2)-abeo-clerodane and clerodane diterpenes from Aristolochia chamissonis

From stems of Aristolochia chamissonis Duch., five new diterpenes, one rearranged (4 --> 2)-abeo-clerodane and four ent-clerodanes, were isolated. Their structures were determined to be (+)-(4 --> 2)-abeo-kolavelool-3-oic acid, (-)-13-epi-2-oxokolavelool, (-)-2 beta-hydroxykolavelool, (-)-2 beta-hydroperoxykolavelool and (+)- 13-epi-2 alpha-hydroxykolavelool. In addition, lignans, sesquiterpenes, steroids and two known ent-clerodane diterpenes were isolated. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

2,3-Dihydrobenzofuran neolignans from Aristolochia pubescens

From a hexane extract of stems and roots of Aristolochia pubescens, the new neolignans (2S,3S,1'R,2'R)- and (2S,3S, 1'S,2'R)-2,3-dihydro-5-(1',2'-dihydroxypropyl)-2-(4-hydroxy-3-methylbenzofuran) and (2S,3S,1'R,2'R)- and (2S,3S,1'S,2'R)-2,3-dihydro-5-(1',2'-dihydroxypropyl)-2-(3,4-dimethoxyphenyl)-7-methoxy-3-methyl-benzofuran were isolated, together with the known neolignan licarin A, and its bisnor-neolignan aldehyde and acid derivatives. In addition, sitosterol, 8R,9R-oxide-beta-caryophyllene, kobusone, ent-kauran-16 alpha, 17-diol, vanillin, vanillic acid, (+)-sesamin, (+)eudesmin, and (-)-cubebin were isolated. The structures of the new compounds have been elucidated by spectroscopic methods and by chemical transformation using Mosher's acid chloride. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

ALKALOIDS FROM ARISTOLOCHIA-ARCUATA

Phytochemical studies with Aristolochia arcuata led to the isolation of KNO3, fructose, sucrose, sitosterol, calarene, its 2-oxo derivative, and three neolignans. Besides which, two new 13-oxidodibenzo[a, g]-quinolizinium alkaloids were isolated. They present only one oxygenated substituent at rings A and D.

Bi- and tetraflavonoids from Aristolochia ridicula

From stems of Aristolochia ridicula, two biflavones, four unusual chalcone-flavone dimers and one tetraflavonoid were isolated. The structures of the seven compounds were elucidated by spectroscopic methods. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Configurational analysis of cubebins and bicubebin from Aristolochia lagesiana and Aristolochia pubescens

(8S,8'R,9S)-, (8R,8'R,9R)-, and (8R,8',R,9S)-cubebins, together with (8R,8'R,8R,8'''R,9R,9S)-bicubebin, were isolated from Aristolochia lagesiana and Aristolochia pubescens. Their structures were determined by spectroscopic methods, including H-1 and C-13 NMR spectroscopy at low temperatures, and by chemical transformations. (c) 2006 Elsevier Ltd. All rights reserved.

Clerodane diterpenes from Aristolochia species

The investigation of Aristolochia brasiliensis and A. esperanzae afforded 12 clerodane derivatives, including the following six novel ones: rel (5S, 8R, 9S, 10R)-2-oxo-ent-3-cleroden-15-oic acid, rel (5S, 8R, 9S, 10R)-2-oxo-ent-clerod-3,13-dien-15-oic acid methyl ester, (5R, 8R, 9S, 10R)-ent-3-cleroden-15-oic acid, rel (5S, 8R, 9S, 10R)-ent-clerod-3,13-dien-15-oic acid, (2S, 5R, 8R, 9S, 10R)-2-hydroperoxy-ent-3-cleroden-15-oic acid methyl ester and (2S, 5R, 8R, 9S, 10R)-2-hydroperoxy-ent-clerod-3,13-dien-15-oic acid methyl ester. The structures were assigned on the basis of spectral data and derivatization by chemical reactions. The occurrence of this type of diterpene has not previously been reported in Aristolochiaceae. © 1987.

Aryltetralone lignans and 7,8-seco-lignans from Holostylis reniformis

Aryltetralone lignans and two 7,8-seco-lignans were isolated from the acetone and hexane extracts of the roots of Holostylis reniformis, together with (-)-galbacin. Their structures were determined by spectroscopic methods. © 2004 Elsevier Ltd. All rights reserved.

Constituintes micromoleculares de Aristolochia melastoma Manso: compostos nitrados

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Métodos de obtenção de lignanas de Holostylis reniformis provenientes de duas regiões brasileiras

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Investigação eletroquímica e aplicação de eletrodos de carbono vítreo modificados por filmes de poli-L-lisina na determinação de antioxidantes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Intraspecific variability of Holostylis reniformis: concentration of lignans, as determined by maceration and supercritical fluid extraction (SFE-CO2), as a function of plant provenance and plant parts

Maceration and supercritical fluid extraction were used to prepare extracts from parts of plants (Holostylis reniformis) collected in two different regions of Brazil. ¹H NMR, HPLC-DAD-ESI/MS, HPLC-DAD, GC-MS, and chemometric techniques were used to analyse lignans in the extracts and showed that yields of SFE-CO2 were less than or equal to those of hexane maceration extracts. These analyses, in conjunction with the concentrations of aliphatic hydrocarbons, fatty acids and their methyl and ethyl derivatives in the extracts, also allowed the chemical composition of parts and provenance of the plant to be differentiated.