RESUMO
We explored the concentration patterns of the bioactive metabolite plumericin produced by Himatanthus tarapotensis (Apocynaceae) under different edaphic conditions and variations in rainfall intensity, as well as its potential role in the chemical defense against insect herbivores. Values of plumericin concentration from leaves were obtained by High-Performance Liquid Chromatography, and evaluated as a function of differences in soil types, variation of precipitation, and variation of the abundance of insect herbivores, using first a Repeated Measures Correlation (rmcorr) and then a Generalized Linear Mixed Model (GLMM) analysis. Plumericin concentration is highly variable among plants, but with a significantly higher concentration in plants growing on clay soil compared to that of the white-sand soil habitat (p < 0.001). Plumericin concentration is not affected by precipitation. The caterpillar of Isognathus leachii (Lepidoptera: Sphingidae) is the most conspicuous herbivore of H. tarapotensis, and its presence is continuous but not related to plumericin concentration, probably because of its capacity to elude the chemical defense of this plant. Nevertheless, our multivariate model revealed that plumericin concentration is related to the abundance of Hymenoptera (Formicidae), and this relationship is significantly influenced by the soil parameters of carbon percentage, clay percentage, and phosphorous percentage (p < 0.001). Plumericin is a mediating agent in the interaction between H. tarapotensis and its natural environment. Variation in plumericin concentration would be induced by the abundance of Hymenoptera (Formicidae), probably as a chemical response against these insects, and by differences in soil nutrient availability.
RESUMO
Uncaria guianensis is native to the Amazon and is used traditionally as an anti-inflammatory. Natural populations of the species have declined markedly in recent times because of strong anthropic pressure brought about by deforestation and indiscriminate collection. The aim of the present study was to assess the genetic and chemical diversity among eight natural populations of U. guianensis located in the Brazilian states of Acre, Amapá and Amazonas. A set of four primer combinations was employed in sequence-related amplified polymorphism (SRAP) amplifications of leaf DNA, and the fragments were analyzed in an LI-COR model 4300 DNA Analyzer. Genetic variability within the populations (81%) was substantially greater than that detected between them (19%). The highest percentage of polymorphic loci (90.21%) and the largest genetic variability were observed in the population located in Mazagão, Amapá. Genetic differentiation between populations was high (Fst = 0.188) and the studied populations formed three distinct genetic groups (K = 3). The population located in Assis Brasil, Acre, presented the highest average content of the mitraphylline (0.60 mg/g dry weight,). However, mitraphylline and isomitraphylline not detected in most individuals in the studied populations, and it is questionable whether they should be considered as chemical markers of the species. The genetic data confirm the urgent need for conservation programs for U. guianensis, and for further studies aimed at ascertaining the genetic basis and heritability of alkaloid accumulation.
Assuntos
Biodiversidade , Conservação dos Recursos Naturais , Extratos Vegetais/análise , Polimorfismo Genético , Uncaria/genética , Brasil , Etnofarmacologia , Alcaloides Indólicos/análise , Medicina Tradicional/métodos , Oxindóis/análise , Extratos Vegetais/química , Folhas de Planta/química , Folhas de Planta/genética , Plantas Medicinais/química , Plantas Medicinais/genética , Uncaria/químicaRESUMO
As part of our continuing chemical and biological analyses of Rubiaceae species from Cerrado, we isolated novel alkaloids 1 and 2, along with known compounds epicatechin, ursolic acid, and oleanolic acid, from Galianthe ramosa. Alkaloid 2 inhibited malate synthase from the pathogenic fungus Paracoccidioides spp. This enzyme is considered an important molecular target because it is not found in humans. Molecular docking simulations were used to describe the interactions between the alkaloids and malate synthase.
Assuntos
Antifúngicos/farmacologia , Carbolinas/farmacologia , Inibidores Enzimáticos/farmacologia , Malato Sintase/antagonistas & inibidores , Paracoccidioides/enzimologia , Alcaloides/química , Alcaloides/farmacologia , Antifúngicos/química , Carbolinas/química , Inibidores Enzimáticos/química , Proteínas Fúngicas/metabolismo , Concentração Inibidora 50 , Malato Sintase/química , Malato Sintase/metabolismo , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Estrutura Molecular , Paracoccidioides/efeitos dos fármacos , Paracoccidioides/patogenicidade , Componentes Aéreos da Planta/química , Rubiaceae/químicaRESUMO
Augusta has traditionally been placed in the tribe Rondeletieae, subfamily Cinchonoideae. However, recent molecular phylogenies positioned it near to Wendlandia (Ixoroideae), but locate A. longifolia near to the clade Ixoroidinae II. The study of A. longifolia afforded two coumarins, five flavonoids, three triterpenoids and one benzoic acid derivative. These metabolites reinforce the separation of Augusta as a monospecific genus, and Lindenia as a genus of three species, closely related to Wendlandia.
Augusta tem sido tradicionalmente colocada na tribo Rondeletieae, Cinchonoideae subfamília. No entanto, recentes filogenias moleculares posicionou-a perto de Wendlandia, porém localizando A. longifolia perto do clado Ixoroidinae II. O estudo de A. longifolia resultou em duas cumarinas, cinco flavonoides, três triterpenoides e um derivado do ácido benzóico. Estes metabolitos reforçam a separação da Augusta como um gênero monoespecífico, e Lindenia como um gênero de três espécies, intimamente relacionada com Wendlandia.