Carbon‐13 nuclear magnetic resonance spectroscopy of naturally‐occurring substances‐ LVII Triterpenes related to lupane and hopane

Wenkert, Ernest; Baddeley, G.; Burfitt, Ivor R.; Moreno, Louis N.

doi:10.1002/mrc.1270110705

Cited by 181 publications

(91 citation statements)

References 19 publications

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“…Elution was carried out using 250-mL fractions of solution varying in concentration from pure hexane to 94% hexane/6% ethyl acetate (v/v%). Twenty-five fractions were collected in this way with 1 appearing in fractions [8][9][10][11][12][13][14][15]. The collected fractions were rechromatographed under similar conditions, yielding 1.3 g of crude compound.…”

Section: Methodsmentioning

confidence: 99%

Total assignment of the ¹³C spectrum of taraxasteryl acetate by ¹³C–¹³C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction

Reynolds¹,

Sawyer²,

Enríquez³

et al. 1985

Can. J. Chem.

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13C–13C connectivity (INADEQUATE) experiments have been used to reassign the 13C spectrum of taraxasteryl acetate. This shows that there were ten errors in an earlier 13C spectral assignment for this compound. An X-ray diffraction investigation of taraxasterol shows that ring E adopts a slightly distorted boat conformation. It is suggested that severe steric interactions in the chair form force it to adopt this unusual conformation. On the basis of the 1H–1H coupling constants, it is concluded that taraxasteryl acetate adopts a very similar conformation in solution. Crystals of taraxasterol–ethanol solvate are orthorhombic, space group P21,21,21, wih a = 7.447(1) Å, b = 17.637(2) Å, c = 22.269(4) Å, U = 2925 Å3, and Dcalc = 1.07 g cm−3 for Z = 4.

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Section: Methodsmentioning

confidence: 99%

Total assignment of the ¹³C spectrum of taraxasteryl acetate by ¹³C–¹³C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction

Reynolds¹,

Sawyer²,

Enríquez³

et al. 1985

Can. J. Chem.

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“…The presence of an additional oxymethine signal indicated that 2 is a hydroxylated lupeol derivative. The localization of the hydroxyl group at C-22 of the lupane framework was proposed by comparison with 13 C NMR data (Table 1) of 16-hydroxylupeol 5 and the correlations observed in the long range HETCOR of H-22 (δ 3.68) and C-28 (δ 12.2), C-19 (δ 45.9) and C-18 (δ 45.1) as well as by the carbon shifts observed in the diacetyl derivative (2a) (Table 1). Thus, the NMR spectra of 2a showed a shielding effect at C-21 (Δδ = -3.5 ppm), which is indicative that C-22 bears a hydroxyl group.…”

Section: Ent-3-oxo-labd-8(17)-en-15-oatementioning

confidence: 99%

“…The labd-8(17)-en-15-oic acid (3) was the predominant compound in this extract. From this compound, derivatives (4)(5)(6)(7)(8) were prepared and some of them were submitted to in vitro antibacterial assays.…”

Section: Introductionmentioning

confidence: 99%

New triterpene and antibacterial labdenoic acid derivatives from Moldenhawera nutans

David¹,

Ferrari²,

David³

et al. 2007

J. Braz. Chem. Soc.

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Um novo triterpeno (22β-hidroxilupeol) foi isolado do extrato em metanol do caule de Moldenhawera nutans (Leguminosae) além de diterpenos derivados do ácido labdenóico de ocorrência comum nesta espécie. A partir do ácido labd-8(17)-en-15-óico foram preparados derivados com atividade in vitro discreta frente à Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella cholerasuis e Vibrio parahaemolyticus.A new triterpene derivative (22β-hydroxylupeol) was isolated from the MeOH extract of stems of Moldenhawera nutans (Leguminosae) together with labdenoic acid derivatives of common occurrence in this species. From the labd-8(17)-en-15-oic acid were prepared simple derivatives, which exhibited in vitro weak activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Salmonella cholerasuis, and Vibrio parahaemolyticus. Keywords: Moldenhawera nutans, Leguminosae, antibacterial labdene derivatives, 22β-hydroxylupeol IntroductionGenus Moldenhawera Schrard. (Leguminosae: Caesalpinoideae), endemic to Northeast Brazil, is represented by approximately ten species. 1 Previous phytochemical study of M. nutans resulted in the isolation of four known labdene diterpenes besides a new bisditerpene named moldenin. 2 The present work describes the results of the fractionation of the hexane phase obtained from the MeOH extract of M. nutans. Besides the known diterpenes previously isolated, it was also obtained the 3-oxo-labd-8(17)-en-15-oic acid (1) as a methyl derivative (1a), and three triterpenes, lupeol, betulin, and the new lupane derivative (2). The labd-8(17)-en-15-oic acid (3) was the predominant compound in this extract. From this compound, derivatives (4-8) were prepared and some of them were submitted to in vitro antibacterial assays. Results and DiscussionThe structural elucidation of 1a (Figure 1) insignificant effect observed at C-19 in the NMR spectra of 2a together with the coupling constants observed in the 1 H NMR suggested that the hydroxyl group is in equatorial position. The 1 HNMR nOe difference spectra of this compound permitted to corroborate the proposition. When the H-22 was irradiated it was possible to assign increments in Hα-21 (25%), H-29 (3%) and, H-19 (10%). These findings are indicative that all the affected protons were in the same plane. The fragmentation pattern observed in the MS of 2 was also indicative of a hydroxyl group in C-22 of the cyclopentyl ring, especially by mass fragments of 2 at m/z 374 and 2a at m/z 458 ( Figure 2). Since labd-8(17)-en-15-oic acid (3) showed antibacterial activity ( Table 2), some of its simple chemical derivatives were prepared and also evaluated. Derivative 3 was refluxed with MeOH/HCl to obtain the isomeric methyl esters 4a and 5. Next, 4a was submitted to allylic oxidation by t-butyl chromate 6 and furnished 6a. It was also prepared the epoxy derivatives 7a and 8a from 4a by reaction with MCPBA. The derivatives 7a and 8a are new and they were characterized by spectrometric analyses data. Compounds 1a, 2, 4a, and 6a-8a w...

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“…Estas frações foram cromatografadas separadamente em coluna de sílica gel, monitoradas por cromatografia em camada delgada. A fração hexânica (1 g), eluída continuamente com hexano/acetona na proporção de 95:5 permitiu a obtenção de 29 mg de um sólido branco, identificado como lupeol (2), cujos dados de IV e RMN ( 1 H e 13 C) são idênticos aos da literatura 14 . Sua estrutura foi confirmada por Co-CCD com uma amostra autêntica adquirida comercialmente.…”

Section: Coleta Do Materials E Preparação Dos Extratosunclassified

Composição química e atividades biológicas das folhas de Cynara scolymus L. (alcachofra) cultivada no Brasil

Noldin¹,

Filho²,

Monachè³

et al. 2003

Quím. Nova

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Our studies demonstrated that glycosyl flavonoids (cynaroside and scolymoside), are the major constituents, along with cynaropicrin, a sesquiterpene lactone, and the triterpene lupeol. Cynarin, which is the main compound described for artichoke, was detected in very low concentration. Hexanic fraction exhibited considerable cytotoxicity and diuretic activities.Keywords: Cynara scolymus; flavonoids; diuretic. INTRODUÇÃOA utilização de plantas medicinais tornou-se um recurso terapêutico alternativo de grande aceitação pela população e vem crescendo junto a comunidade médica, desde que sejam utilizadas plantas cujas atividades biológicas tenham sido investigadas cientificamente, comprovando sua eficácia e segurança 1,2 . A importância das plantas medicinais deve-se também por sua contribuição como fonte natural de fármacos e por proporcionar grandes chances de obter-se uma molécula protótipo devido à diversidade de constituintes presentes nestas [2][3][4][5] . No entanto, inúmeras plantas que são usadas em preparações fitoterápicas carecem de um maior controle de qualidade, uma vez que a literatura científica indica que muitas destas podem apresentar substâncias tóxicas ou composição química variável 6,7 . Assim, o presente estudo teve como objetivos investigar a composição química e os efeitos biológicos da Cynara scolymus Linné, cultivada no Brasil. Esta planta é conhecida popularmente como alcachofra, pertencente à família Compositae, que compreende cerca de 920 gêneros com aproximadamente 19 mil espécies, cujos hábi-tos são muito variados 8 . A C. scolymus é oriunda do Mediterrâneo, sendo que seu cultivo se dá por sementes e está difundido mundialmente, já que é utilizada para fins medicinais e alimentícios.Os principais componentes químicos presentes nas folhas da alcachofra são os ácidos fenólicos, flavonóides e sesquiterpenos. A cinarina (1) (ácido monocafeioilquínico) é relatada como princípio ativo da planta 9,10 . Vários estudos biológicos com extratos brutos e purificados de alcachofra, realizados tanto em animais quanto em humanos, demonstraram atividades hipolipidêmica, hepatoprotetora, colerética, colagoga, antioxidante e outras [11][12][13] . Cabe ressaltar, porém, que os estudos encontrados na literatura são abordados com plantas cultivadas na Europa. Considerando a variabilidade da composição química devido a vários fatores (ambientais, sazonais, etc), optou-se em investigar a composição química da alcachofra cultivada no Brasil e que está presente em várias preparações fitoterápicas. PARTE EXPERIMENTAL Coleta do material e preparação dos extratosUtilizou-se folhas da C. scolymus, oriundas da Central de Plantas em Curitiba, coletadas em fevereiro de 2000, as quais foram devidamente identificadas e posteriormente secas e moídas. Este material (1900 g) foi macerado estaticamente por sete dias com metanol, sendo, em seguida, concentrado, usando-se evaporador rotatório sob pressão reduzida, para obtenção do extrato metanólico bruto (EMB) 2 . Este foi particionado com solventes de polaridade crescente, ...

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Carbon‐13 nuclear magnetic resonance spectroscopy of naturally‐occurring substances‐ LVII Triterpenes related to lupane and hopane

Cited by 181 publications

References 19 publications

Total assignment of the ¹³C spectrum of taraxasteryl acetate by ¹³C–¹³C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction

Total assignment of the ¹³C spectrum of taraxasteryl acetate by ¹³C–¹³C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction

New triterpene and antibacterial labdenoic acid derivatives from Moldenhawera nutans

Composição química e atividades biológicas das folhas de Cynara scolymus L. (alcachofra) cultivada no Brasil

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Carbon‐13 nuclear magnetic resonance spectroscopy of naturally‐occurring substances‐ LVII Triterpenes related to lupane and hopane

Cited by 181 publications

References 19 publications

Total assignment of the 13C spectrum of taraxasteryl acetate by 13C–13C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction

Total assignment of the 13C spectrum of taraxasteryl acetate by 13C–13C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction

New triterpene and antibacterial labdenoic acid derivatives from Moldenhawera nutans

Composição química e atividades biológicas das folhas de Cynara scolymus L. (alcachofra) cultivada no Brasil

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Product

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Total assignment of the ¹³C spectrum of taraxasteryl acetate by ¹³C–¹³C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction

Total assignment of the ¹³C spectrum of taraxasteryl acetate by ¹³C–¹³C connectivity experiments and determination of the stereochemistry of taraxasterol by X-ray diffraction