Composição química e atividade biológica do óleo essencial de Siparuna guianensis Aublet (Siparunaceae)

Abstract

The negramina medicinal plant (Siparuna guianensis Aublet) belongs to the Siparunaceae family; it is a monoecious shrub with simple leaves, elliptic and elongated membranous, smooth edges, with unisexual flowers and dehiscent fruit. The change in the producement of their essential oils as well as their chemical composition can be observed in different studies conducted in various regions of the country due to its phenology and interactions with the environment. It is also known as capitiú, fedegoso, erva santa, among others. It is mainly used in the form of decoctions and showers against colds, sinusitis, body pain, inflammatory diseases and “malina”. The objective of this study was to collect and extract the essential oils from fresh leaves of the species Siparuna guianensis Aublet during the rainy and dry season in the region of Cantá localized on north of Roraima, belong to Amazon, and conduct a study on the possible seasonal variations concerning to the chemical composition and biological activity, whose oils were subjected to antimicrobial activity tests, inhibition of enzyme acetilcolinasterase, capturing stable free radical DPPH and toxicity against Artemia salina. Essential oils extracted via hidrodesltilation obtained divergent results for the periods, and the proportion of oil extracted in the dry period was higher than the rainy season. The samples were characterized by gas chromatography coupled to a spectrophotometer GC-MS mass. Samples of the rainy season compounds were identified: iso- shyobunona (21,45%) and shyobunona (19%) and in the dry season were the the iso- shyobunona (16,2%) and T- muurolol (11,7%). The average inhibition values of the samples taken during the rainy season of the essential oils of S. guianensis on the bacteria Staphylococcus aureus (50,81% - 69,84%) is being Gram- positive , and Citrobacter freundii (52,77% - 80,93 %) Gram - negative and during the dry period the test samples had average inhibition above 50 % for Listeria monocytogenes 52,1% and 79,1% for Citrobacter freundi from 50,6% to 66,9%, with potential inhibitory minimum to positive and Gram negative bacteria, with biological potential regarding the adopted standards. In acetylcholinesterase test, the samples showed better inhibitions in June and July, 76.57 % and 51,82%, respectively, considered inhibitory. The results of the enzyme activity acetilcolinasterase of samples of essential oils obtained S.guianensis percentage of 56,4% to 82,5% being considered inhibitors acetilcolinasterase enzyme and potential agents against Alzheimer. The test for the antioxidant activity resulted by the capturing of the stable free radical DPPH one of essential oils extracted from samples in wet and dry period does not show the potential to be used as an antioxidant, the percentages of concentrations tested were relatively low. The front testing Artemia salina, determined a LD50 392.38 μg.mL-1 being considered moderately toxic.