Proceedings of Oncobiology Symposiums
Proceedings of XIV Oncobiology Symposium

INTRODUCTION AND OBJECTIVE: Cancer was the second leading cause of death in 2018 and oral squamous cell carcinoma (OSCC) stands out for the high mortality and low survival rate and low treatment evolution in the last 30 years. Therefore, the development of new treatments becomes necessary. Plants in the genus Equisetum are popularly used in the treatment of various diseases including cancer. The aim of this study was to perform phytochemical analysis of the E.hyemale stem (EHS), evaluation of the antiproliferative effect and determination of the cell death pathway induced by the extracts in the OSCC and determination of its main chemical constitutes.

MATERIAL AND METHODS: Ethanolic crude extract was prepared from the EHS. Subsequently, crude stem extract was partitioned in N-hexane (EHH), dichloromethane (EHD) and ethyl acetate (EHA) and clonogenic and cell viability assays were performed with MTT. The IC50 was calculated by non-linear regression curve Cell morphology was analyzed by microscopy and cell death with propidium iodide. Hemolysis tests were performed with goat blood. The concentration of phenols and flavonoids were quantified based on gallic acid and quercetin, respectively. The partitions were analyzed by LC-MS/MS. Acute toxicity tests were performed on C57 Black/6J according to the CEUA/UFF #982 protocol. The cells used were SCC9, SCC4, SCC25 and primary culture fibroblast.

RESULTS AND CONCLUSION: Through the clonogenic assays and MTT assays with the crude extract IC50 of 200.6±0.09 μg/mL was calculated. In the cell viability assay with the partitions the IC50, EHA (64.5±0.072 μg/mL) was calculated and the EHH and EHD fractions did not reach 50% inhibition at the concentrations tested. As a positive control, Carboplatin chemotherapy (280,4±0,05 μg/mL) was used. The morphology of cells treated with EHA showed increased cytoplasm, large amounts of granules and vacuolesThe EHA partition was shown to be less hemolytic than the control, reduced the absolute number of cells in culture and induced its permeabilization of the tumor cells. The EHA was also tested on tumor lines SCC4 IC50 54,53±0,047μg/mg and SCC25 64±0,014μg/mL. Comparing the IC50 of the SCC9 with Fibroblasto EHA demonstrated the selectivity index (SI) of 2,070 and Carbo 1,865. The EHA fraction presented (0.41±0.17 μg/mg) phenol and (0.85±0.10 μg/mg) flavonoids. The LS / MS results are still being analyzed, but azelaic acid was the only substance specifically identified in EHA so far. The EHA partition does not show macroscopic changes in the animals. After analysis of the results, it can be concluded that the Equisetum hyemale stem extract has a cytotoxic effect against oral squamous cells, with the EHA fraction being the most selective. Analysis of LC mass (LC-MS/MS) is being performed to identify possible active compounds.