Influência diversidade genética, de fatores ambientais e da fenologia sobre o metabolismo secundário de Tithonia diversifolia HEMSL (ASTERACEAE).
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2018-05-04
Autores
Pretti, Irany Rodrigues
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Universidade Federal do Espírito Santo
Resumo
Tithonia diversifolia belongs to the Asteraceae family, is native from Mexico and widely distributed in tropical and subtropical regions. It is a plant used in countries of Central America, South America, Africa and Asia for the treatment of diseases as diabetes, malaria, abscesses, bruises, skin infections, gastric ulcer, diarrhea, menstrual cramps and wounds. More than 150 compounds were isolated from T. diversifolia, and their main chemical constituents are sesquiterpene lactones, flavonoids and phenolic compounds derived from trans-cinnamic acid. Secondary metabolites act as a chemical interface between plants and the surrounding environment, so their synthesis is often affected by environmental conditions. The production of secondary metabolites is determined by four main factors: genetic, ontogenic, morphogenetic and environmental. The quality of the phytotherapic product results from the interaction between the conditions of the growth site of the medicinal plants and the genetic characteristics of the population. The objectives of this work were to evaluate the genetic diversity of populations of T. diversifolia through RAPD genetic markers, as well as to analyze the influence of environmental and phenological factors in the production of phenolic compounds, besides the antioxidant, cytotoxic and mutagenic activity of these plants. The results demonstrated high levels of genetic diversity were found, not positively correlated with geographical proximity, and the population of Santa Teresa (ST) presented a lower similarity than the others. T. diversifolia reproduces sexually, with abundant seed production and a great variety of pollinating insects, characteristics that contribute to a greater genetic variability. The levels of phenolic compounds were higher in the ST population at the vegetative stage, as well as, in general, also showed the higher antioxidant activity. Among the environmental factors considered, the temperature seems to act more significantly in the production of phenolic compounds in T. diversifolia. The phytochemical composition of plants may vary significantly during the phenological cycle. Therefore, it is very important to identify and select ideal ontogenic stages, to produce the largest quantities of bioactive compounds and guarantee homogeneity of the quality of the raw material. In general, the highest levels of phenolic compounds were found in the plants collected at the vegetative stage. The extract showed a higher cytotoxic activity on the cancer cell line (S180), which shows that the extract acts differentially in the two cell lines evaluated (S180 and human lymphocytes). This characteristic highlights that T. diversifolia presents therapeutic potential for the development of new drugs. The extract of the investigated plant showed no mutagenic activity in peripheral blood cells of mice. This study indicates that phytochemical and antioxidant variations among populations are influenced by genetic factors and phenological stage, as well as by environmental conditions.
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Phenolics compounds , Antioxidant , Compostos fenólicos , Environmental factors , Fatores ambientais , Cytotoxicity , Mutagenicidade , Mutagenicity , Citotoxicidade
Citação
PRETTI, Irany Rodrigues. Influência diversidade genética, de fatores ambientais e da fenologia sobre o metabolismo secundário de Tithonia diversifolia HEMSL (ASTERACEAE). 2018. 139 p. Tese (Doutorado em Biologia Vegetal) - Universidade Federal do Espírito Santo, Centro de Ciências Humanas e Naturais, Vitória, 2018.