Investigação dos efeitos da disponibilidade hídrica em parâmentros fotossintéticos e no metabolismo especializado de “pata-de-vaca” Bauhinia ungulata na era das mudanças climáticas
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Data
2020-02-17
Autores
Souza, Ana Júlia Borim de
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Universidade Estadual Paulista (Unesp)
Resumo
Resumo Bauhinia ungulata L. (Fabaceae) é utilizada na medicina tradicional para o tratamento de diabetes, pela presença de flavonoides com potencial hipoglicemiante e esses metabólitos estão envolvidos na sobrevivência das plantas. Períodos de seca são limitantes da fotossíntese e interferem no metabolismo da planta, o que é preocupante dado à previsão de mudanças climáticas, e devem ser analisados sob o ponto de vista agronômico para garantir material vegetal com qualidade para produção de fármacos. Visando avaliar os impactos da variação da disponibilidade hídrica em plantas medicinais, este trabalho teve como objetivo avaliar parâmetros fotossintéticos e o metabolismo especializado de espécimes de B. ungulata submetidos a três diferentes períodos de irrigação: diária (Controle), com interrupções por sete dias (7D) e por quinze dias (15D) durante 90 dias. Amostras de folhas foram congeladas, liofilizadas e submetidas a extração com MeOH 70% em ultrassom. Numa primeira etapa foi realizada análise fitoquímica do extrato por RMN 1D e 2D e por cromatografia líquida de ultra eficiência acoplada a espectrômetro de massas de alta resolução (UHPLC-HRMS). A anotação dos compostos foi realizada por comparação de espectros disponíveis na plataforma Global Natural Products Social (GNPS) e organizados em uma rede de moléculas. Variações no metabolismo especializado foram investigadas por meio de análises em espectrômetro de Ressonância Magnética Nuclear (RMN) com abordagem metabolômica seguida de análise multivariada. Parâmetros fotossintéticos foram investigados in planta através da mensuração de trocas gasosas por meio de um analisador de gás infra-vermelho (IRGA). O estudo fitoquímico possibilitou a identificação de treze flavonoides derivados de quercetina, canferol, miricetina, isorhamnetina e datiscetina, além de 4,4’-dihidroxibibenzil e prolina. A análise dos parâmetros fotossintéticos mostrou que a variação da disponibilidade hídrica reduziu a condutância estomática, fotossíntese e transpiração nos grupos 7D e 15D em comparação com o grupo controle (p>0.05). A partir da análise multivariada, foi possível observar alterações nos espectros de RMN de 1H na região dos sinais 6 a 7 ppm, e na região 1,80-3,9 ppm atribuída à prolina, um aminoácido responsável por conferir proteção osmorreguladora em resposta a situações de seca severa. Esse aminoácido foi correlacionado positivamente ao grupo 15D, diferentemente dos sinais da região dos compostos fenólicos. Esses resultados mostram que a diminuição da disponibilidade hídrica induziu alterações nos parâmetros fotossintéticos, que reduzem a produção de matéria verde e compostos fenólicos de interesse medicinal em B. ungulata. Essas alterações têm impactos negativos tanto no fornecimento de material para produção de fármacos, quanto para a sua sobrevivência em condições previstas nos cenários das mudanças climáticas, que preveem maiores períodos de seca num futuro próximo. Entretanto, do ponto de vista agronômico, os resultados indicam que apenas uma irrigação por semana, por até 60 dias, não ocorre alterações significativas no acúmulo de biomassa e substâncias relevantes no ponto de vista medicinal.
Abstract Bauhinia ungulata L. (Fabaceae) is used in traditional medicine for the treatment of diabetes, due to the presence of flavonoids with hypoglycemic potential. Dry periods are limiting photosynthesis and interfere with plant metabolism, which is worrisome given the prediction of climate change, and should be analyzed from an agronomic point of view to ensure plant material with quality for the drugs production. In order to evaluate the impacts of the variation in water availability in medicinal plants, this study aimed to evaluate photosynthetic parameters and specialized metabolism of B. ungulata specimens submitted to three different periods of irrigation: daily (Control), with interruptions for seven days (7D) and for fifteen days (15D) for 90 days. Leaf samples were frozen, freeze-dried and extracted with 70% MeOH on ultrasound. In a first step, phytochemical analysis of the extract was performed by 1D and 2D NMR and by ultra efficiency liquid chromatography coupled to a high resolution mass spectrometer (UHPLC-HRMS). A molecular network (MN) was generated using the Global Natural Products Social Platform (GNPS) workflow. Compounds in the MN were annotated against the GNPS spectral database in level 2. Variations in specialized metabolism were investigated by nuclear magnetic resonance (NMR) spectrometer analyses with metabolomic approach followed by multivariate analysis. Photosynthetic parameters were investigated in planta by measuring gas exchange by means of an infra-red gas analyzer (IRGA). The phytochemical study allowed the identification of thirteen flavonoids derived from quercetin, canferol, myricetin, isorhamnetin and datiscetin, in addition to 4,4'-dihydroxybibenzand and proline. The analysis of photosynthetic parameters showed that the variation in water availability reduced stomatal conductance, photosynthesis and transpiration in the 7D and 15D groups compared to the control group (p>0.05). From the multivariate analysis, it was possible to observe changes in the 1H NMR spectra in the region of signals 6 to 7 ppm, and in the region 1.80-3.9 ppm attributed to proline, an amino acid responsible for conferring osmorregulatory protection in response to drought situations. This amino acid was positively correlated to the 15D group, differently from the signals of the phenolic compounds region. These results show that the decrease in water availability induced changes in photosynthetic parameters, which reduce the production of green matter and phenolic compounds of medicinal interest in B. ungulata. These changes have negative impacts on the supply of material for drug production and on plant survival under conditions predicted in climate change scenarios, which predict longer periods of drought in the near future. From the agronomic point of view, our results indicate that only one irrigation per week, for up to 60 days, dont cause significant changes in the accumulation of biomass and substances relevant from the medicinal point of view.
Abstract Bauhinia ungulata L. (Fabaceae) is used in traditional medicine for the treatment of diabetes, due to the presence of flavonoids with hypoglycemic potential. Dry periods are limiting photosynthesis and interfere with plant metabolism, which is worrisome given the prediction of climate change, and should be analyzed from an agronomic point of view to ensure plant material with quality for the drugs production. In order to evaluate the impacts of the variation in water availability in medicinal plants, this study aimed to evaluate photosynthetic parameters and specialized metabolism of B. ungulata specimens submitted to three different periods of irrigation: daily (Control), with interruptions for seven days (7D) and for fifteen days (15D) for 90 days. Leaf samples were frozen, freeze-dried and extracted with 70% MeOH on ultrasound. In a first step, phytochemical analysis of the extract was performed by 1D and 2D NMR and by ultra efficiency liquid chromatography coupled to a high resolution mass spectrometer (UHPLC-HRMS). A molecular network (MN) was generated using the Global Natural Products Social Platform (GNPS) workflow. Compounds in the MN were annotated against the GNPS spectral database in level 2. Variations in specialized metabolism were investigated by nuclear magnetic resonance (NMR) spectrometer analyses with metabolomic approach followed by multivariate analysis. Photosynthetic parameters were investigated in planta by measuring gas exchange by means of an infra-red gas analyzer (IRGA). The phytochemical study allowed the identification of thirteen flavonoids derived from quercetin, canferol, myricetin, isorhamnetin and datiscetin, in addition to 4,4'-dihydroxybibenzand and proline. The analysis of photosynthetic parameters showed that the variation in water availability reduced stomatal conductance, photosynthesis and transpiration in the 7D and 15D groups compared to the control group (p>0.05). From the multivariate analysis, it was possible to observe changes in the 1H NMR spectra in the region of signals 6 to 7 ppm, and in the region 1.80-3.9 ppm attributed to proline, an amino acid responsible for conferring osmorregulatory protection in response to drought situations. This amino acid was positively correlated to the 15D group, differently from the signals of the phenolic compounds region. These results show that the decrease in water availability induced changes in photosynthetic parameters, which reduce the production of green matter and phenolic compounds of medicinal interest in B. ungulata. These changes have negative impacts on the supply of material for drug production and on plant survival under conditions predicted in climate change scenarios, which predict longer periods of drought in the near future. From the agronomic point of view, our results indicate that only one irrigation per week, for up to 60 days, dont cause significant changes in the accumulation of biomass and substances relevant from the medicinal point of view.
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Palavras-chave
Flavonoides, Metabolômica, Padronização, Planta medicinal, Flavonoids, Medicinal plant, Metabolomics, Standardization