Estudo das lignanas de Peperomia blanda (Piperaceae): abordagem de aspectos estruturais, metabólitos e biossintéticos
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Data
2013-02-15
Autores
Felippe, Lidiane Gaspareto [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O estudo fitoquímico precedente da espécie Peperomia blanda culminou no isolamento de lignanas tetraidrofurânicas e secolignanas. Alguns isômeros destas secolignanas apresentaram configurações absolutas diferentes daquelas já relatadas, as quais foram determinadas por comparação dos espectros experimentais de dicroísmo circular vibracional e eletrônico com aqueles preditos por cálculos mecânico-quânticos ab initio. A peperomina B teve a configuração absoluta assinalada como (2S,3S,5S), confirmando a estrutura química descrita na literatura, a substância 2-metil-3-[bis(3′,4′-metilenodioxi-5′-metoxifenil) metil]butirolactona foi assinalada como (2R,3S) e a substância 2-metil-3-[5-(3′,4′-metilenodioxi-5′-metoxifenil)-5-(3′,4′,5′-trimetoxifenil)metil]butirolactona foi assinalada como (2R,3S,5S). As dinâmicas metabólicas sazonais de três lignanas tetraidrofurânicas e três secolignanas foram determinadas a partir de análise por CLAE-DAD dos extratos metanólicos de partes aéreas e raízes de duas populações de P. blanda, utilizando planejamento experimental e validação do método cromatográfico. O maior acúmulo destas substâncias foi observado nas raízes, especialmente nos meses de julho e em espécies coletada na Reserva Florestal da Ripasa. Alguns fatores climáticos, como a disponibilidade hídrica, foram determinantes para a produção destes metabólitos. Uma das lignanas tetraidrofurânicas, com oxidação na posição C-9, bem como as secolignanas, tiveram alguns aspectos biossintéticos abordados pela incorporação de precursores em extratos enzimáticos. Os estudos das vias biossintéticas envolvidas na formação dessas lignanas foram iniciados com a investigação e otimização das reações catalíticas da enzima fenilalanina amônia liase (PAL). A condição ótima reacional foi determinada por...
The previous phytochemical study of Peperomia blanda species culminated in the isolation of secolignans and tetrahydrofuran lignans. Some of these secolignans isomers showed different absolute configurations from those reported in the literature, which were determined by comparison of experimental vibrational and electronic circular dichroism spectra with those calculated using ab initio quantum mechanical methods. The stereochemistry of peperomin B was assigned as (2S,3S,5S) confirming the previous related structure, the compound 2-methyl-3-[bis(3′,4′-methylenedioxy-5′-methoxyphenyl)methyl] butyrolactone was assigned as (2R,3S) and the compound 2-methyl-3-[5-(3′,4′-methylenedioxy-5′-methoxyphenyl)-5-(3′,4′,5′-trimethoxyphenyl)methyl] butyrolactone was assigned as (2R,3S,5S). The seasonal metabolic dynamic of three tetrahydrofuran lignans and three secolignans were determined by HPLC-DAD analysis of methanolic extracts of aerial parts and roots of two populations of P. blanda, using experimental design and validation of the chromatographic method. The largest accumulation of these substances was observed in the roots, specially in July and in the species collected in the Ripasa's Forest Reserve. Some climatic factors such as water availability were critical for the production of these metabolites. One of the tetrahydrofuran secolignans with oxidation at C-9 as well as the secolignans were studied from the biosynthetic point of view using cell free extracts. These studies were started with the investigation and optimization of catalytic reactions of the enzyme phenylalanine ammonia lyase (PAL). The optimum reaction condition was determined by experimental design which showed better conversion of L-phenylalanine to trans-cinnamic acid at 51 °C and pH 9.2. The... (Complete abstract click electronic access below)
The previous phytochemical study of Peperomia blanda species culminated in the isolation of secolignans and tetrahydrofuran lignans. Some of these secolignans isomers showed different absolute configurations from those reported in the literature, which were determined by comparison of experimental vibrational and electronic circular dichroism spectra with those calculated using ab initio quantum mechanical methods. The stereochemistry of peperomin B was assigned as (2S,3S,5S) confirming the previous related structure, the compound 2-methyl-3-[bis(3′,4′-methylenedioxy-5′-methoxyphenyl)methyl] butyrolactone was assigned as (2R,3S) and the compound 2-methyl-3-[5-(3′,4′-methylenedioxy-5′-methoxyphenyl)-5-(3′,4′,5′-trimethoxyphenyl)methyl] butyrolactone was assigned as (2R,3S,5S). The seasonal metabolic dynamic of three tetrahydrofuran lignans and three secolignans were determined by HPLC-DAD analysis of methanolic extracts of aerial parts and roots of two populations of P. blanda, using experimental design and validation of the chromatographic method. The largest accumulation of these substances was observed in the roots, specially in July and in the species collected in the Ripasa's Forest Reserve. Some climatic factors such as water availability were critical for the production of these metabolites. One of the tetrahydrofuran secolignans with oxidation at C-9 as well as the secolignans were studied from the biosynthetic point of view using cell free extracts. These studies were started with the investigation and optimization of catalytic reactions of the enzyme phenylalanine ammonia lyase (PAL). The optimum reaction condition was determined by experimental design which showed better conversion of L-phenylalanine to trans-cinnamic acid at 51 °C and pH 9.2. The... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Quimica organica, Biossintese, Lignanas, Biosynthesis
Como citar
FELIPPE, Lidiane Gaspareto. Estudo das lignanas de Peperomia blanda (Piperaceae): abordagem de aspectos estruturais, metabólitos e biossintéticos. 2013. 182 f. Tese (doutorado) - Universidade Estadual Paulista Júlio de Mesquita Filho, Instituto de Química de Araraquara, 2013.