Avaliação de espécies vegetais nativas e adaptadas do estado do Amazonas contra aedes aegypti, vetor responsável por diferentes doenças de impacto na saúde pública

Abstract

The target botanical species of this work, Ampelozizyphus amazonicus (Ducke) (Rhamnaceae), Alpinia zerumbet (B.L. Burtt & R.M. Sm.) (Zingiberaceae), Blepharocalyx sp. (Kiaerskou; L.R. Landrum) (Myrtaceae), Endlicheria sp. (Meisn.; C.K. Allen) (Lauraceae), Virola sp. (Warb) (Myristicaceae), Bocageopsis sp. (Mart.) (Annonaceae), Origanum vulgare L. and Thymus vulgaris L. (Lamiaceae), can be found in the state of Amazonas, and in other regions of the Brazilian Amazon. These plants are widely used in folk medicine and have several classes of secondary metabolites in the chemical constitution of their vegetative parts. In the present study, the extract of A. amazonicus was tested for its antioxidant activity through the ability to scavenge the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH), using quercetin as a standard. The methanol extracts of the thin and thick stems of A. amazonicus, with a sequestration capacity equal to (CS50) 119.06 ± 0.62 μg/mL and 125.03 ± 0.68 μg/mL, respectively, showed similar activity. In the toxicity test against Artemia salina, teas from thick stems using two different methodologies, showed moderate activity with median lethal concentrations of 125.8 and 198.0 µg/mL, respectively. The in vitro digestive simulation carried out with teas from the fresh and dry stems of A. amazonicus allowed a better understanding of the possible enzymatic reactions occurring in the gastrointestinal tract due to the changes in the chromatographic profile observed for the preparations in the form of tea, using different extraction methodologies . The substances 5-allyl-1-(2,3,4,-tris-O-benzoylpentofuranosyl)-2,4(1H,3H)-pyrimidinedione (tR 5.5 min. and [M-H]- m/z 595, 1665) and phloretin-3',5'-di-glycoside (tR 8.6 min. and [M-H]- m/z 597.1834) were identified as the major substances in the chromatographic profiles of A. amazonicus teas and whose signals on the chromatogram, after in vitro digestive processes, decreased. The analysis of the volatiles of the species A. zerumbet obtained through the Headspace technique indicated the terpenes 1,8-cineol and 1,4-terpineol as major substances for all the analyzed samples, with values above 10% of the composition of the volatiles. For Blepharocalyx sp., Endlicheria sp., Virola sp., Bocageopsis sp., Origanum vulgare and Thymus vulgaris species, it was observed that all essential oils showed toxicity to Aedes aegypti larvae, with Virola sp. and O. vulgare with the lowest 24-hour median lethal concentration values of 36.6 μg/mL and 37.5 μg/mL, respectively. In tests with adult mosquitoes of Ae. aegypti the oils of the species Bocageopsis sp., Virola sp. and T. vulgaris showed high adulticidal activity, with LC50 of 12.5 µg/mL, 12.7 µg/mL and 12.8 µg/mL, respectively. The results obtained from the repellent action of O. vulgare and T. vulgaris oils demonstrate potential at concentrations of 0.5% with an escape percentage of 37.8% and 68.9%, respectively. Docking calculations and molecular dynamics performed for the terpenes 4-terpineol, carvacrol, thymol, cymene and terpinene, in the active site of the AeSCP-2 protein, revealed potential larvicidal activity for essential oils with higher concentrations of 4-terpinenol, carvacrol and thymol. The results presented for the extracts and essential oils studied demonstrate the importance of chemical and biological investigation of the plant species listed for the development of prophylactic treatments or for action in the fight against vectors responsible for the transmission of diseases that impact public health.