Desreplicação de extratos de flores do gênero Aristolochia com destaque ao isolamento dos constituintes químicos de Aristolochia gigantea
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Data
2022-09-27
Autores
Cunha, Camila Luiza
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Universidade Estadual Paulista (Unesp)
Resumo
O gênero Aristolochia (Aristolochiaceae) possui 84 espécies catalogadas no Brasil. Na medicina popular são amplamente utilizadas por serem abortivas/emenagogas, estomáquicas, analgésicas, no tratamento de picada de cobra, feridas e doenças da pele e por ajudarem no emagrecimento. Essas espécies são conhecidas por apresentar flores com características morfológicas e com mecanismo de polinização bem peculiares. Apesar dessas particularidades acerca do gênero Aristolochia há somente três estudos químicos relacionados a extratos de flores dessas espécies descritos na literatura. Dessa maneira, o objetivo desse trabalho foi contribuir para o conhecimento da composição química de flores de Aristolochia, por meio de métodos analíticos de desreplicação e através do isolamento e identificação estrutural dos compostos majoritários. Para isso a fração acetato de etila, obtida do extrato etanólico de flores de A. gigantea, foi submetida a fracionamento cromatográfico levando ao isolamento, e posterior identificação, de quatro fenilpropanoides, dois derivados do ácido benzoico, seis ácidos aristolóquicos e dois flavonoides. Dois dos fenilpropanoides isolados estão sendo descritos pela primeira vez na literatura. Um planejamento do tipo simplex centroide foi realizado para avaliar a influência de diferentes sistemas de solventes na extração dos constituintes químicos das flores de A. esperanzae, A. holostylis, A. gardneri, A. labiata, A. gehrtii e A. gigantea. Os resultados revelaram que nenhum dos sistemas de solventes testados foi considerado ideal para ser usado no preparo de extratos de todas as espécies de flores de Aristolochia. Por fim, as frações hexânicas e metanólicas, obtidas a partir dos extratos obtidos no planejamento experimental, foram analisadas por técnicas analíticas de desreplicação. A análise das frações hexânicas por CG-EM sugeriu a presença de 37 substâncias pertencentes as classes dos terpenoides, ácidos graxos, álcoois, cetonas, lignanas, além de homólogos de alcanos. Já a análise das frações metanólicas por CLAE-EM, utilizando a abordagem de redes moleculares, permitiu anotar 17 substâncias pertencentes as classes dos alcaloides, lignanas e flavonoides.
The genus Aristolochia (Aristolochiaceae) has 84 species cataloged in Brazil. In folk medicine these species are widely used because they are abortifacients/emmenagogues, stomachic, analgesic, in the treatment of snakebite, wounds and skin diseases and for helping to lose weight. These species are known to have flowers with very peculiar morphological characteristics and pollination mechanism. Despite these particularities concerning the genus Aristolochia, there are only three chemical studies related to flowers extracts described in the literature. Thus, the objective of this work was to contribute to the knowledge of the chemical composition of Aristolochia flowers, through analytical methods of dereplication and through the isolation and structural identification of the major compounds. For this, the ethyl acetate fraction, obtained from the ethanolic extract of A. gigantea flowers, was subjected to chromatographic fractionation leading to the isolation, and subsequent identification, of four phenylpropanoids, two benzoic acid derivatives, six aristolochic acids and two flavonoids. Two of the isolated phenylpropanoids are being described for the first time in the literature. A centroid simplex design was carried out to evaluate the influence of different solvent systems on the extraction of chemical constituents from the flowers of A. esperanzae, A. holostylis, A. gardneri, A. labiata, A. gehrtii and A. gigantea. The results revealed that none of the tested solvent systems was considered ideal to be used in the preparation of extracts from all species of Aristolochia flowers. Finally, the hexane and methanolic fractions, obtained from the extracts obtained in the experimental design, were analyzed by analytical dereplication techniques. The analysis of hexane fractions by GC-MS suggested the presence of 37 compounds belonging to the classes of terpenoids, fatty acids, alcohols, ketones, lignans, in addition to homologs of alkanes. The analysis of the methanolic fractions by HPLC-MS, using the molecular network approach, allowed to note 17 compounds belonging to the classes of alkaloids, lignans and flavonoids.
The genus Aristolochia (Aristolochiaceae) has 84 species cataloged in Brazil. In folk medicine these species are widely used because they are abortifacients/emmenagogues, stomachic, analgesic, in the treatment of snakebite, wounds and skin diseases and for helping to lose weight. These species are known to have flowers with very peculiar morphological characteristics and pollination mechanism. Despite these particularities concerning the genus Aristolochia, there are only three chemical studies related to flowers extracts described in the literature. Thus, the objective of this work was to contribute to the knowledge of the chemical composition of Aristolochia flowers, through analytical methods of dereplication and through the isolation and structural identification of the major compounds. For this, the ethyl acetate fraction, obtained from the ethanolic extract of A. gigantea flowers, was subjected to chromatographic fractionation leading to the isolation, and subsequent identification, of four phenylpropanoids, two benzoic acid derivatives, six aristolochic acids and two flavonoids. Two of the isolated phenylpropanoids are being described for the first time in the literature. A centroid simplex design was carried out to evaluate the influence of different solvent systems on the extraction of chemical constituents from the flowers of A. esperanzae, A. holostylis, A. gardneri, A. labiata, A. gehrtii and A. gigantea. The results revealed that none of the tested solvent systems was considered ideal to be used in the preparation of extracts from all species of Aristolochia flowers. Finally, the hexane and methanolic fractions, obtained from the extracts obtained in the experimental design, were analyzed by analytical dereplication techniques. The analysis of hexane fractions by GC-MS suggested the presence of 37 compounds belonging to the classes of terpenoids, fatty acids, alcohols, ketones, lignans, in addition to homologs of alkanes. The analysis of the methanolic fractions by HPLC-MS, using the molecular network approach, allowed to note 17 compounds belonging to the classes of alkaloids, lignans and flavonoids.
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Palavras-chave
Aristolochiaceae, Aristolochia, Espectrometria de massas, Redes moleculares, Mass spectrometry, Molecular networking