RESUMO
Plant secondary metabolism evolved in the context of highly organized and differentiated cells and tissues, featuring massive chemical complexity operating under tight environmental, developmental and genetic control. Biotechnological demand for natural products has been continuously increasing because of their significant value and new applications, mainly as pharmaceuticals. Aseptic production systems of plant secondary metabolites have improved considerably, constituting an attractive tool for increased, stable and large-scale supply of valuable molecules. Surprisingly, to date, only a few examples including taxol, shikonin, berberine and artemisinin have emerged as success cases of commercial production using this strategy. The present review focuses on the main characteristics of plant specialized metabolism and their implications for current strategies used to produce secondary compounds in axenic cultivation systems. The search for consonance between plant secondary metabolism unique features and various in vitro culture systems, including cell, tissue, organ, and engineered cultures, as well as heterologous expression in microbial platforms, is discussed. Data to date strongly suggest that attaining full potential of these biotechnology production strategies requires being able to take advantage of plant specialized metabolism singularities for improved target molecule yields and for bypassing inherent difficulties in its rational manipulation.
Assuntos
Produtos Biológicos/metabolismo , Biotecnologia/métodos , Engenharia Metabólica/métodos , Compostos Fitoquímicos/biossíntese , Células Vegetais/metabolismo , Plantas/metabolismo , Artemisininas/isolamento & purificação , Artemisininas/metabolismo , Cultura Axênica , Berberina/isolamento & purificação , Berberina/metabolismo , Produtos Biológicos/isolamento & purificação , Técnicas de Cultura de Células , Naftoquinonas/isolamento & purificação , Naftoquinonas/metabolismo , Paclitaxel/biossíntese , Paclitaxel/isolamento & purificação , Compostos Fitoquímicos/isolamento & purificação , Células Vegetais/química , Plantas/química , Plantas/genética , Metabolismo Secundário , Técnicas de Cultura de TecidosRESUMO
N,ß-D-glucopyranosyl vincosamide (GPV), a major alkaloid of Psychotria leiocarpa, constitutes up to 2.5% of the dry weight in leaves. Alkaloid content was not elicited by mechanical wounding or jasmonate. At concentrations found in natural conditions or 2.5 fold higher, GPV did not inhibit herbivory in two unrelated generalist models (Helix aspersa and Spodoptera frugiperda) or in a specific interaction model (Heliconius erato fed with Passiflora suberosa). In situ staining assay showed quenching activity of hydrogen peroxide by GPV. Exposure of P. leiocarpa to acute UV-B stress did not change GPV or chlorophyll content, indicating high tolerance to this stress by the species. In vitro antioxidant tests against singlet oxygen, superoxide anions and hydroxyl radicals showed efficient quenching activity of the alkaloid. GPV was not effective as antifeedant, but it may act indirectly in P. leiocarpa protection against oxidative stress generated upon wounding, UV exposure and perhaps other environmental stresses.
Assuntos
Antioxidantes/química , Glucose/análogos & derivados , Alcaloides Indólicos/química , Folhas de Planta/química , Psychotria/química , Glucose/química , Radical Hidroxila/química , Estresse Oxidativo , Oxigênio Singlete/química , Superóxidos/químicaRESUMO
Este trabalho visa identificar as espécies comercializadas como quebra-pedras em Porto Alegre, verificar indícios de toxicidade e estabelecer padrões morfológicos para diferenciação das mesmas. São espécies utilizadas na medicina popular principalmente para afecções nos rins e bexiga bem como diuréticas. As 16 amostras foram adquiridas de 14 comerciantes atuantes em bancas fixas ou em feiras-livres. Realizou-se uma revisão bibliográfica para levantamento de dados referentes à utilização de plantas medicinais com o nome de quebra-pedras em diferentes cidades do Rio Grande do Sul. Indícios de toxicidade, dados químicos e biológicos destas plantas foram revisados em diferentes bases de dados e em bibliografia específica. Identificaram-se sete espécies comercializadas como quebra-pedras em Porto Alegre: Euphorbia prostrata e E. serpens (Euphorbiaceae), Phyllanthus niruri e P. tenellus (Phyllanthaceae), Desmodium incanum (Fabaceae), Cunila microcephala (Lamiaceae) e Heimia salicifolia (Lythraceae). Destas, as espécies de Phyllanthus e Euphorbia são as que apresentam maior semelhança morfológica quando comercializadas secas e fragmentadas.
The aims of this work were to identify the species sold as "quebra-pedras" in Porto Alegre, verify signs of toxicity and establish morphological patterns that help to distinguish such species. Those species are believed to be diuretic and are used in popular medicine mainly to treat kidney and bladder affections. The samples (16) were purchased from 14 sellers who work in permanent market stalls or in public marketplaces. A bibliographic revision gathered data on the use of medicinal plants called "quebra-pedras" in several cities of Rio Grande do Sul. Signs of toxicity, chemical and biological data of these plants were reviewed from different databases and specific bibliography. Seven species were identified among those sold as "quebra-pedras" in Porto Alegre: Euphorbia prostrata and E. serpens (Euphorbiaceae), Phyllanthus niruri and P. tenellus (Phyllanthaceae), Desmodium incanum (Fabaceae), Cunila microcephala (Lamiaceae) and Heimia salicifolia (Lythraceae). The greater morphological similarity when dried and fragmented plants are sold together was verified between Phyllanthus and Euphorbia.