A fração diclorometano obtida pelo particionamento do extrato hidroalcoólico obtido das folhas e flores de Vernonia scorpioides (Asteraceae) resultou no isolamento e caracterização de um novo poliacetileno, 5-octa-2,4,6-triinil-furan-2(5H)-ona. A determinação estrutural foi baseada em dados de espectrometria de Ressonância Magnética Nuclear mono e bidimensionais, de Massas e de Infravermelho. Foi investigado o potencial antitumoral e genotóxico do novo poliacetileno e os resultados encontrados sugerem genotoxicidade e citotoxicidade, onde a morte celular ocorreu via apoptose, envolvendo um mecanismo dependente de caspase.The dichloromethane fraction obtained from hydroalcoholic crude extract of leaves and flowers of Vernonia scorpioides (Asteraceae) was investigated, resulting in the isolation and structure elucidation of a new polyacetylene namely 5-octa-2,4,6-triynyl-furan-2(5H)-one. The structure of the isolated compound was determined based on IR, NMR (1D and 2D) and MS spectrometric data. The antitumor potential, including cytotoxicity to tumor cells and genotoxicity, was investigated. The results suggest that apoptotic cell death may have occurred, at least in part, via a caspasedependent mechanism.Keywords: polyacetylene, Vernonia scorpioides, cytotoxicity, genotoxicity, Asteraceae
IntroductionThe widespread genus Vernonia (Asteraceae) is characterized by the fact that it produces highly oxygenated sesquiterpene lactones, such as glaucolides and hirsutinolides, some of which are allenic lactones. Many other compounds have also been isolated, such as thiophenes and dithio compounds.1,2 Among the species of Vernonia, cytotoxicity has been described for isolated sesquiterpene lactones from V. cinerea, 3 V. lasiopus, 4 and V. amygdalina. 5 Besides sesquiterpene lactones, polar compounds from water-soluble extracts of Vernonia have also been found to have cytotoxic and imunomodulatory activities such as those from the edible leaves of V. amygdalina 6 and from the roots of V. kotschyana 7 and V. anthelmintica.
8The species Vernonia scorpioides (Lam.) Pers., which is very common in Brazil, is popularly known as "Piracá", "Enxuga" or "Erva-de-São-Simão" and usually grows in poor deforested neotropical soils.9 Alcoholic extract from the fresh leaves is widely used in topical applications, to treat a variety of skin disorders, including chronic wounds, such as ulcers of the lower limbs. In previous studies, chloroform and hexane crude extracts of V. scorpioides leaves have shown fungicide activity, 10 moderate bactericide activity and mild wound healing effects.11 In addition, in mice treated with dichloromethane extract of the leaves, the Ehrlich tumor disappeared completely.12 Therefore, as part of our ongoing search for bioactive compounds of V. scorpioides, a new polyacetylene isolated from the dichloromethane fraction is described, and its antitumor potential, as well as in vitro cytotoxicity to tumor cells and cell death via genotoxicity, are evaluated.
Results and DiscussionThe crude ethanol extract of V. s...