Investigação fitoquímica e avaliação da atividade antioxidante das folhas e frutos de Eugenia jambolana Lam. (Myrtaceae)
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Data
2007-08-27
Autores
Plaza, Carenina Vidotte [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A família Myrtaceae apresenta ampla distribuição, ocorrendo, preferencialmente, nas zonas tropicais e subtropicais, e é considerada uma das mais importantes famílias da flora brasileira em função da larga ocorrência de espécies comestíveis e/ou usadas na medicina tradicional. Eugenia jambolana Lam. é conhecida no Brasil como jambolão, e é de grande interesse pelas aplicações medicinais, especialmente de suas folhas e frutos, no tratamento da diabetes. O trabalho tem como objetivo a investigação fitoquímica das folhas e frutos de E. jambolana monitorado por testes para detecção de atividade potencialmente antioxidante, através dos métodos de descoramento do b-caroteno e seqüestro do radical DPPH. Folhas e frutos da planta em estudo foram coletados na Faculdade de Ciências e Letras - UNESP/CAr. Foi obtido o extrato etanólico das folhas que foi particionado com solventes de diferentes polaridades. Para a obtenção do extrato bruto dos frutos (casca e polpa) foi utilizado MeOH (1% HCl). O estudo fitoquímico das folhas através de técnicas cromatográficas usuais (cromatografia em coluna, CLAE e cromatografia em contra corrente de alta velocidade) resultou no isolamento de dois flavonóides que apresentaram atividade antioxidante em ensaio com solução de b-caroteno. Os flavonóides isolados foram identificados como 4'-Oramnopiranosídeo- 3',5,5',7-tetraidroxi-flavona (1) e miricetrina (2). Análises em CLAE-DAD das frações provenientes do extrato bruto das frutas evidenciaram a presença de três antocianinas majoritárias e uma minoritária, que foram detectadas por análises de CLAE-DAD e CLAE-MS, e em comparação com dados da literatura, proporcionou a identificação das mesmas como cianidina-3-xilosídeo, cianidina-3- glucosídeo, cianidina-3-rutinosídeo e cianidina-3-(6''-acetoil)-glicosídeo. As frações FrX-4, FrX-442, FrX-452 e FrX-5...
The Myrtaceae family is widely distributed and occurs, mostly, in tropical and subtropical areas. It is one of the most important families of the Brazilian flora owing to the wide occurrence of edible species and/or species used in the traditional medicine. Eugenia jambolana Lam. is known in Brazil as jambolão and is of great interest for its folk medicinal applications, especially of their leaves and fruits, in the treatment of diabetes. Leaves and fruits of this species have been collected at UNESP (University Campus). The ethanol extract of the leaves was partioned with organic solvents and the crude extract of the fruits (skin and pulp) was obtained with acidified methanol (1% HCl). The phytochemical study of the leaves extract using chromatographic techniques (column chromatography, TLC, HPLC and HSCCC) resulted in the isolation of two flavonoids which presented strong antioxidant activity in the TLC assay using b-carotene solution as revealing agent. The isolated flavonoids have been identified as 4'-Oramnopyranoside- 3',5',5,7-tetrahydroxy-flavone (1) and myricetrin (2). Their strong antioxidant activity could be related with the presence of hydroxy groups in ring B which provides increased stability to the radical formed after donation of a hydrogen radical, and also the presence of the _,_-unsaturated carbonyl moiety on C ring.. HPLC-DAD analyses of the fractions obtained from the crude extract of the fruits evidenced the presence of three major anthocyanins and a minor one, which been identified by analyses of HPLC-DAD and HPLC-MS data, and comparison with literature. They were identified as cyanidin-3-xyloside, cyanidin-3-glucoside, cyanidin-3-rutinoside and cyanidin-3- (6''-acetoyl)-glucoside. Anthocyanin-rich fractions were evaluated for their free radical scavenging activity towards the stable free radical DPPH and evidenced stronger activity ...(Complete abstract click electronic access below)
The Myrtaceae family is widely distributed and occurs, mostly, in tropical and subtropical areas. It is one of the most important families of the Brazilian flora owing to the wide occurrence of edible species and/or species used in the traditional medicine. Eugenia jambolana Lam. is known in Brazil as jambolão and is of great interest for its folk medicinal applications, especially of their leaves and fruits, in the treatment of diabetes. Leaves and fruits of this species have been collected at UNESP (University Campus). The ethanol extract of the leaves was partioned with organic solvents and the crude extract of the fruits (skin and pulp) was obtained with acidified methanol (1% HCl). The phytochemical study of the leaves extract using chromatographic techniques (column chromatography, TLC, HPLC and HSCCC) resulted in the isolation of two flavonoids which presented strong antioxidant activity in the TLC assay using b-carotene solution as revealing agent. The isolated flavonoids have been identified as 4'-Oramnopyranoside- 3',5',5,7-tetrahydroxy-flavone (1) and myricetrin (2). Their strong antioxidant activity could be related with the presence of hydroxy groups in ring B which provides increased stability to the radical formed after donation of a hydrogen radical, and also the presence of the _,_-unsaturated carbonyl moiety on C ring.. HPLC-DAD analyses of the fractions obtained from the crude extract of the fruits evidenced the presence of three major anthocyanins and a minor one, which been identified by analyses of HPLC-DAD and HPLC-MS data, and comparison with literature. They were identified as cyanidin-3-xyloside, cyanidin-3-glucoside, cyanidin-3-rutinoside and cyanidin-3- (6''-acetoyl)-glucoside. Anthocyanin-rich fractions were evaluated for their free radical scavenging activity towards the stable free radical DPPH and evidenced stronger activity ...(Complete abstract click electronic access below)
Descrição
Palavras-chave
Quimica organica, Flavonoides, Antioxidantes, Antocianinas, Antioxidants
Como citar
PLAZA, Carenina Vidotte. Investigação fitoquímica e avaliação da atividade antioxidante das folhas e frutos de Eugenia jambolana Lam. (Myrtaceae). 2007. 107 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química, 2007.