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Doctoral Thesis
DOI
10.11606/T.46.1997.tde-28112014-151532
Document
Author
Full name
Dulce Helena Siqueira Silva
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1997
Supervisor
Committee
Yoshida, Massayoshi (President)
Fernandes, João Batista
Ferraz, Helena Maria Carvalho
Lopes, Lucia Maria Xavier
Rezende, Daisy de Brito
Title in Portuguese
Constituintes químicos de Iryanthera sagotiana e Iryanthera lancifolia
Keywords in Portuguese
Antioxidante
Bioquímica vegetal
Fitoquímica
Flavonolignana
Iryanthera
Myristicaceae
Produtos naturais
Química orgânica
Tocotrienol
Abstract in Portuguese
O presente trabalho descreve o isolamento, identificação e determinação estrutural dos constituintes químicos das inflorescências e folhas de Iryanthera sagotiana e das inflorescências e pericarpos de I. lancifolia, espécies da família Myristicaceae, que ocorrem na Amazônia. A investigação fitoquímica das inflorescências de I. sagotiana (Benth.) Warb. forneceu, após extração, partição com solventes orgânicos e fracionamentos cromatográficos, quatro diidrochalconas: 2',4'-diidroxi-4,6'- dimetoxidiidrochalcona (I) ; 2',4',6'-triidróxi-4-metoxidiidrochalcona; 2',4,4'-triidróxi-6'-metoxidiidrochalcona (II) e 2',4'-diidroxi-4-metóxi-6'-glicopiranosil-diidrochalcona, sendo as duas últimas, inéditas. Foram também isolados e identificados o benzaldeído, o ácido diidro-p-cumárico, dois flavonóis glicosilados: afzelina e quercitrina e quatro flavanonóis glicosilados: engeletina, isoengeletina, astilbina e isoastilbina. Das folhas de I. sagotiana foram isoladas as diidrochalconas I, II e o dímero 3',3"'-bis-2', 4',6'-triidróxi-4-metoxidiidrochalcona, inédito na literatura, além da afzelina, quercitrina, engeletina e astilbina. Os pericarpos de I. lancifolia Ducke forneceram, após procedimentos cromatográficos, as diidrochalconas I e 2',4-diidróxi-4',6'dimetoxidiidrochalcona, inédita, e três flavonolignóides também inéditos: rel (1"R,2"R,3"S)-3'-(1",4"-di-p-hidroxifenil-2",3"-dimetilbutil)-2',4'-diidróxi-4,6'-dimetoxidiidrochalcona (III); rel (1"R,2"S,3"R)-3'-(1",4"-di-p-hidroxifenil-2",3"-dimetilbutil)-2',4'-diidróxi-4,6'-dimetoxidiidrochalcona (IV) e 5'-(1",4"-di-p-hidroxifenil-2",3"-dimetilbutil)-2',6'-diidróxi-4,4'dimetoxidiidrochalcona. Foram isoladas também três lactonas policetídicas inéditas: (2S,3S,4S)-2-(7-dodecenil)-3-hidróxi-4-metil-butanolido, rel (2S,3R,4S)-2-(7'-dodecenil)-3-hidróxi-4-metil-butanolido e 2-dodecil-3-hidróxi-4-metil-but-2-enolido, além do tocotrienol 2,8-dimetil-2-(4,8,12-trimetil-3,7,11-tridecatrienil)-6-cromanol e da lignana (8R,TS,8'S)-4,4'diidróxi-2,7'-ciclolignana. Das inflorescências de I. lancifolia foram isolados a diidrochalcona I, os flavonolignóides III e IV, o tocotrienol e o esteróide 3-β-O-β-D-galactopiranosilsitosterol. A elucidação estrutural das substâncias isoladas foi baseada em métodos espectrométricos: EM, RMN de 1H e 13C (PND e DEPT 135°), técnicas de RMN bidimensionais (HOMOCOSY e HETERO-COSY) e experimentos para a observação de NOE. Reações de acetilação e epoxidação foram efetuadas para se obterem derivados mais informativos. As atividades antioxidantes da afzelina, da quercitrina, do flavonolignóide IV e do tocotrienol foram avaliadas em comparação com a atividade antioxidante da vitamina E, empregando-se a inibição da autooxidação de homogenato de cérebro como modelo experimental. A capacidade antioxidante foi medida pela produção de malonildialdeído (MDA) e a concentração necessária para inibir 50% da autoxidação (Ql/2) foi calculada. Os valores de Ql/2 obtidos para afzelina, quercitrina, flavonolignóide, tocotrienol e vitamina E foram, respectivamente: 62,30; 2,29; 4,83; 1,08 e 11,20 µM. Estes ensaios foram realizados pela pesquisadora Dra. Solange C. Davino e pela professora Dra. Sílvia B. M. Barros, da Faculdade de Ciências FarmacêutIcas da USP.
Title in English
Chemical constituents Iryanthera sagotiana and Iryanthera lancifolia
Keywords in English
Antioxidant
Iryanthera
Myristicaceae
Natural products
Organic chemistry
Phytochemistry
Plant biochemistry
Tocotrienol
Abstract in English
This work describes the isolation, identification and structural elucidation of chemical constituents from inflorescences and leaves of Iryanthera sagotiana (Myristicaceae) and from inflorescences and pericarps of I. lancifolia, collected in Amazon region. After extraction and partition with organic solvents and chromatographic fractionation, phytochemical analysis of inflorescences of I. sagotiana (Benth.) Warb. afforded four dihydrochalcones: 2',4'-dihydroxy-4,6'dimethoxydihydrochalcone (I); 2',4',6'-trihydroxy-4-methoxy-dihydrochalcone; and the new 2',4,4'-trihydroxy-6'-methoxy-dihydrochalcone (II) and 2',4'-dihydroxy- 4-methoxy-6'-glucopyranosyl-dihydrochalcone. Benzaldehyde, dihydro-p-cumaric acid besides two glycosylated flavonols: afzelin and quercitrin and four glycosylated flavanonols: engeletin, isoengeletin, astilbin and isoastilbin were also isolated and identified. Leaves of I. sagotiana yielded dihydrochalcones I, II and the new dimer 3',3"'-bis-2',4',6'-trihydroxy-4-methoxydihydrochalcone in addition to afzelin, quercitrin, engeletin and astilbin. Pericarps of I. lancifolia Ducke afforded, after fractionation procedures, dihydrochalcones I e 2',4-dihydroxy-4',6'-dimethoxy-dihydrochalcone, which has not been reported in literature yet, as well as three new flavonolignoids: rel (1"R,2"R,3"S)-3'-(1",4"-di-p-hydroxyphenyl-2",3"dimethylbutyl)-2',4'-dihydroxy-4,6'-dimethoxydihydrochalcone (III); rel (1"R,2"S,3"R)-3'-(1",4"-di-p-hydroxyphenyl-2",3"-dimethylbutyl)-2',4'-dihydroxy-4,6'-dimethoxydihydrochalcone (IV) e 5'-(1",4"-di-p-hydroxyphenyl-2",3"dimethylbutyl)-2',6'-dihydroxy-4,4'-dimethoxy-dihydrochalcone. Three new polyketide lactones were also isolated: (2S,3S,4S)-2-(7-dodecenyl)-3-hydroxy-4-methyl-butanolide, rel (2S,3R,4S)-2-(7'-dodecenyl)-3-hydroxy-4-methylbutanolide e 2-dodecyl-3-hydroxy-4-methyl-but-2-enolide, besides tocotrienol 2,8-dimethyl-2-(4,8,12-trimethyl-3,7,11-tridecatrienyl)-6-cromanol and lignan (8R,T'S,8'S)-4,4'-dihydroxy-2, 7'-cyclo1ignan. From inflorescences of I. lancifolia, dihydrochalcone I, flavonolignoids III e IV, tocotrienol and the steroid 3-β-O-β-D-galactopyranosylsitosterol were isolated. Structural elucidation of the isolated compounds were based on spectrometric methods: MS, 1H and 13C NMR (PND and DEPT 135°), bidimensional NMR techniques (HOMOCOSY e HETERO-COSY) as well as NOE experiments. Acetylation and epoxidation reactions were carried out in order to get more informative derivatives. Antioxidant activities of afzelin, quercitrin, flavonolignoid IV and tocotrienol were evaluated in comparison with the antioxidant activity of vitamin E, using the inhibition of autoxidation of brain homogenates as a experimental model. The antioxidant capacity was measured by malondialdehyde (MDA) production and the necessary concentration to inhibit 50% of autoxidation (Q12) was calculated. The following values of Q1/2 were obtained for afzelin, quercitrin, flavonolignoid, tocotrienol and vitamin E, respectively: 62,30; 2,29; 4,83; 1,08 e 11,20 µM.
 
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Publishing Date
2014-11-28
 
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