Estudo da composição química e atividades biológicas do óleo volátil da Psidium myrtoides O. Berg (Araçá-roxo)

Abstract

The present work had a general objective of evaluating the chemical composition and the biologic properties of the volatile oil of the Psidium myrtoides O. Berg plant. Volatile oils were extracted from fresh leaves and dry leaves in the dry and rainy season. The extraction was performed by hydrodistillation using the Clevenger apparatus. The identification variation of the chemical composition of the volatile oils obtained from the rainy season and the dry period was determined by GC /MS. Twenty-five compounds were identified in the dry period, and 22 compounds were identified in the rainy season (for both volatile oils from fresh leaves and dry leaves). In both the dry and rainy periods (for both volatile oils of fresh leaves and dry leaves), the major compounds were: α-copaene, trans-caryophyllene, α-humulene, caryophyllene oxide, humulene epoxide II and α-bisabolol. The presence of oxygenated sesquiterpenes (41.32%) was higher in the volatile oil obtained from the dry leaf, while in the volatile oil obtained from the fresh leaf, the presence of oxygenated sesquiterpenes was lower (36, 00%). In the volatile oil obtained from the fresh leaf, in the rainy period, there was a greater presence of oxygenated sesquiterpenes (52.34%). In the volatile oil obtained in the same period (rainy period), from the dry leaf, there was less presence of oxygenated sesquiterpenes (37.21%). The evaluation of the free-radical scavenging capacity using the peroxyl radical (ORAC method), showed that all volatile oils presented antioxidant activity, especially the volatile oil of the fresh leaf of the rainy season with the highest antioxidant activity (2491.1μmoleq/g), being the activity associated with the greater presence of oxygenated sesquiterpenes. The antimicrobial activity against anaerobic and aerobic oral pathogens was evaluated by broth microdilution method. In general, all the oils presented low activity against the aerobic and anaerobic microorganisms evaluated, being Streptococcus sanguinis with MIC value of 200 µg.mL-1, representing moderate activity. The antifungal activity of all volatile oils presented strong activity against Candida glabrata yeasts, with a MIC value of 46.87 µg.mL-1for the volatile oil tested on the dry leaf in the dry period. By the selectivity index calculation greater selectivity by Trypanosoma cruzi IC50 (54.05 µg.mL-1) than toxicity for the Vero CC50 cells (71.77 µg.mL-11) was verified for the volatile oil tested of the dry leaf from the dry period. By the Selectivity Index (IS), greater selectivity of Trypanosoma cruzi (IC50 54.10 μg.mL-1; IS 0.12) was verified than toxicity to Vero cells (CC50 71.77 μg.mL- 1) for the volatile oil tested from the dry leaf, in the dry period. The selectivity index was also found to be more selective for Leishmania amazonensis (IC50 31.8 μg.mL-1, 55.7 μg.mL-1; IS 0.23; 0.08, respectively) than for cell toxicity Vero (CC50 53.79 μg.mL-1; 66.57 μg.mL-1), respectively, for the volatile oil obtained from the fresh leaf and volatile oil obtained from the dry leaf, in the rainy season. Simulated molecular docking results have revealed that the volatile oil components of Psidium myrtoides form complexes with the α-amylase and pancreatic lipase enzymes, and may be new drug candidates in the fight against type II diabetes and obesity.