Name: IRANY RODRIGUES PRETTI
Type: PhD thesis
Publication date: 04/05/2018
Advisor:
Name |
Role |
|---|---|
| Maria do Carmo Pimentel Batitucci | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Claudia Masrouah Jamal | External Examiner * |
| Elias Terra Werner | Internal Examiner * |
| Maria do Carmo Pimentel Batitucci | Advisor * |
| Paulo Cezar Cavatte | Internal Examiner * |
| Ricardo Machado Kuster | External Examiner * |
Summary: 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.
Keywords: Phenolics compounds antioxidant environmental factors RAPD
cytotoxicity mutagenicity
