Avaliação da atividade citotóxica e pró-apoptótica de Croton blanchetianus baill. em linhagens de câncer cervical humano

Abstract

Cervical cancer (CC) is the third most common cancers in women worldwide and the fourth major cause of cancer death in the woman in developing countries. High-risk human papilloma viruses (HPVs) such as HPV 16, 18, 31 and 33 have been attributed to be the major risk factors for cervical cancer, out of which HPV-16 and -18 account for almost 70% of the cancers. Platinum-based chemotherapy in combination with radiotherapy or surgery is now mainly used to treat CC, but the efficacy is limited especially in advanced-stage disease. Furthermore, these treatments could easily lead to adverse reactions and drug resistance. Thus, it is necessary to seek antitumor drugs of high efficacy for the treatment of this kind of tumor. Croton blanchetianus (CB), known as “black marmeleiro”, belongs to the family Euphorbiaceae and it is a widely disseminated shrub found in northeast Brazil. Some studies have demonstrated cytotoxic activity of plants of this genus against human tumor cell lines. However, to date, there is nothing described in the literature as to the cytotoxic effect of the Croton blanchetianus. Therefore, the present study aimed to investigate, in vitro, the effects of leaves and root fractions from Croton blanchetianus (CB) against human cervical cancer HeLa and SiHa cells. Fractions were obtained by pH variation method, from which were obtained two acidic fractions, one of the leaves (CBaF) and root (CBaR) and two basic also obtained from leaves (CBbF) and root (CBbR). Phytochemical screening was evaluated by thin layer chromatography. Cytotoxic activity and cell death evaluation were determined with MTT and annexin V/PI assays by flow cytometry, respectively. Nuclear morphological changes were evaluated by fluorescence with DAPI stanning and flow cytometry was used to cycle assay. According to results, most of the fractions exhibited terpenoids, alkaloids and flavonoids. All fractions decreased significantly cell viability of HeLa and SiHa cells in a concentration- and time-dependent manner, promoted cellular and nuclear morphological changes and induced apoptosis and cell cycle arrest. This is the first study that demonstrated cytotoxic and pro apoptotic effects of CB on HeLa and SiHa cells. Therefore, CB appears to be a valuable natural source for the development of agents for the treatment of CC. However, more studies are needed to isolate, purify and elucidate the possible action mechanisms of the active compounds.