The influence of environmental factors and seasonal variation of Tithonia diversifolia (Hemls.) A. Gray metabolites and evaluation of the antioxidant, photoprotective and photochemopreventive activities of the extracts in vitro

Author(s)

Bruno Leite Sampaio

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2015-09-25

Examining board members

Fernando Batista da Costa; Sérgio Ricardo Ambrosio; Maria Jose Vieira Fonseca; Luiz Alberto Beraldo de Moraes; Monica Tallarico Pupo

• Advisor: Fernando Batista da Costa

Abstract

Margaridão, the common name of the species Tithonia diversifolia (Hemls.) A. Gray (Asteraceae), is an invasive plant native from both Mexico and Central America, encountered in different tropical and subtropical ecosystems. It is popularly used for the treatment of various health problems such as inflammation, malaria, and gastritis. Despite the various pharmacologic and phytochemical studies in the literature about this plant, there are few studies on the variation of its metabolites, especially considering the effects of seasonality and environmental influence, so that studies relating this possible variation to biological activity are still rarer. In this work we investigated the influence of different abiotic environmental factors (climate and soil) on the metabolites of this plant by combining modern analytical techniques such as UHPLC-DAD-(ESI)-HRMS and NMR (J-resolved), combined with multivariate statistical methods, and the effect of the variation of the metabolic profile for the antioxidant and photoprotective activities in vitro using cultured cells. The analysis of samples of T. diversifolia by UHPLC-DAD-(ESI)-HRMS and NMR (J-resolved) provided new information which enable to elucidate better the seasonal variation pattern of the metabolic profile for the different parts of the plant related to the influence of the environmental factors, using unsupervised (HCA and PCA) and supervised (OPLS-DA) multivariate analysis methods. It was also possible to observe differences in the metabolic profiles of extracts of T. diversifolia specimens collected in different regions of Brazil using a similar approach to that used for the study of seasonal variation, highlighting that, despite the differences, it was possible observe the presence of sesquiterpene lactones as major compounds in most of the samples analysed. The assays for antioxidant activity in vitro, allowed the choice of extracts with better features for the photoprotective and photochemopreventive in vitro efficacy tests. The results of the assays to evaluate the antioxidant activity demonstrated the existence of differences for this activity between the parts of the plant, being the leaves and roots more actives, mainly by scavenging free radical mechanism, so that leaf and root extracts were used for testing in cell culture. The two extracts showed evaluated photoprotective activity for both cell lines tested after exposure to UV-A radiation, by reducing intracellular ROS formation, and increased cell viability of HaCaT keratinocytes exposed to UV-B radiation. The extracts of T. diversifolia have shown no significantly phototoxicity for any of the tested cell lines after exposure to UV-B radiation. Photochemoprevention was observed for the strain HaCaT in which the leaf extract increased the cell viability after exposure to UV-B radiation at the three highest tested concentrations, while at higher concentration (20.0 mg/mL), there was no difference statistically significant compared to non-irradiated control. The leaf extract also showed photochemopreventive activity by inhibiting lipid peroxidation in cultured HaCaT keratinocytes exposed to UV-B radiation. Considering all results presented herein, we highlight the environment-metabolism relationship for T. diversifolia and the selected set of analytical and statistical techniques allowed us to obtain reliable data that contributed to a holistic understanding of the role of metabolism in the plant\'s adaptation to the environment, and the potential of this approach to the rational search for natural products with biological activity of interest (AU)

• FAPESP's process: 11/13361-6 - Evaluation of seasonal variation of the main secondary metabolites and anti-inflammatory activity of extracts of Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae)
• Grantee: Bruno Leite Sampaio
• Support Opportunities: Scholarships in Brazil - Doctorate