Isolation, identification and mechanism of action of anticancer active principles of Croton campestris A.St.-Hil.

Abstract

The increase in life expectancy and habits that increase exposure to carcinogens such as tobacco, alcohol and bad diet, have been increasing the incidence of cancer. This is related to the action of carcinogens that favors the appearance of disease. Cancer is the second leading cause of death in the population. Tumor cells are characterized by ignoring the signals that regulate cell proliferation, differentiation process and apoptosis, and present a high capacity for invasion and metastasis. The most chemotherapeutic drugs used in cancer treatment comes from natural sources. The anticancer activity of extracts from the leaves of Croton campestris A.St.-Hil. was initially evaluated by the Division of Pharmacology and Toxicology in project financed by FAPESP (FAPESP-Bioprospecta 2004/07943-9), which executed the screening of 200 extracts species of São Paulo. This plant was evaluated also in a scientific initiation project (FAPESP 2006/61249-2) that compared the anticancer activity of extracts obtained from species popularly used for treatment of parasitic diseases. The results directed the master's project already concluded (FAPESP 2010/02945-4). This study deepened the evaluation and characterized the anticancer activity of extracts and fractions obtained from C. campestris. Potent anticancer activity was observed in cultures of human tumor cells, especially for lung line (NCI-H460), and in in vivo experimental models that presented inhibition of tumor development in mice Ehrlich solid. The work of isolation was guided by the testing activity in cultured tumor cells and identified, so far, the diterpenes velamone and velamolone among the probably anticancer principles. The current project will continue this work in order to isolate and identify active compounds with anticancer activity, and to determine its mechanism of action. In this work we will assessed the cellular pathways involved in the antitumor activity besides we will evaluate other corroborative actions of this activity, as inhibition of angiogenesis and metastatic processes. Extraction, fractionation, isolation and identification of the active principles will be biomonitored through tests in cultured of human tumor cells and normal keratinocyte line. The lines with selectivity for the active principles, as observed for NCI-H460 (lung), will be selected for the study of mechanism of cell death by flow cytometry. We will investigate also the cell death markers such as p53, p21, bcl-2, among others that will enable the assessment of death pathways involved. From the results obtained in cell culture, the active principles will be evaluated in two in vivo experimental models: Ehrlich's solid tumor and through implantation of the semi-permeable fibers (hollow fiber) in mice, containing human tumor cells in order to evaluate the effectiveness of the active principles under metabolic processes. The study is a pioneer for this species and has shown promising results, which confirms its continuity with the long-term goal of providing a new compound for the cancer treatment.