Avaliação da toxicidade e mutagenicidade de extratos etanólicos de folhas de Petiveria alliacea Linnaeus em Escherichia coli e DNA plasmidial

Abstract

Petiveria alliacea L. is an herbaceous plant, included to the family Phytolaccaceae, native to the Amazonic region and popularly known “amansa-senhor”, “piu-piu” e “guiné”. It is widely used in popular medicine with several therapeutic activities, such as, analgesic, antibacterial, antifungal and hypoglycemic properties. However, their toxicological effects are not well elucidated. The objective of the present study is to evaluate cytotoxicity and the genotoxicity of crude ethanolic extracts of leaves of P. alliacea in Escherichia coli and plasmid DNA. The leaves of plants collected in Rio de Janeiro (22º 53’ 55.95’’S and 43º 05’ 09.37W) were dried to 50 ºC during 24 hours and submitted to the preparation of the crude ethanolic extract by infusion, followed by rotary evaporation. In order to evaluate the cytotoxic potential of the extract, cultures of E. coli wild-type (AB1157) were incubated with different concentrations of the plants extract (5, 10, 15, 20, 25 e 30 mg/mL), for 60 minutes and the survival fractions were obtained. The genotoxicity was performed through agarose gel electrophoresis using both bacterial DNA and pUC9.1 plasmid DNA. Besides, the plasmid transformation efficiency was also evaluated. The obtained data indicate that the P. alliacea ethanolic leaves extract shown a cytotoxic effect only in high concentrations tested. It could be linked to DNA stand breaks in vivo, observed after bacterial DNA electrophoresis. However, the agarose gel electrophoresis of plasmid DNA incubated with different extract concentrations did not show strand breaks, but a crescent delay in DNA migration through the agarose gel. Besides, incubation of plasmid DNA with P. alliacea extract was not able to change the transformation efficiency. The P. alliacea ethanolic extract did not show mutagenic activity and its partitions not shown cytotoxic action. Together, the results suggest that P. alliacea possess a toxic potential that could be responsible to DNA lesions and decreasing in bacterial survival. The lack of DNA damage and absence of alterations in transformations assay indicate that bacterial metabolism could be responsible for chemical modifications in the extract compounds, leading to DNA damage and bacterial death