Nanoemulsões carreadas com óleos essenciais de Piper alatipetiolatum e Piper purusanum (Piperaceae) como bioinseticidas no controle dos vetores da dengue e malária

Abstract

Mosquitoes of the genera Aedes and Anopheles are the main transmitters of chikungunya, zika and malaria, respectively worldwide. The control of these vectors is a public health problem due to resistance to synthetic insecticides. However, nanoemulsions carried with essential oils present an alternative and safe tool in the control of these mosquitoes. The objective of this study was to identify the efficiency of nanoemulsions carried with the essential oils of Piper alatipetiolatum and Piper purusanum in the control of arboviruses and malaria vectors. The essential oil of P. alatipetiolatum with yield of 7.6 ± 0.3% was characterized mainly with sesquiterpene (67%) and oxygenated sesquiterpenes (33%). The main substances were ishwarone (78.58%), β-elemene (6.87%), ishwarane (2.36%) e selin-11-en-4α-ol (2.88%) e ishwarol (8.2%). While the essential oil of P. purusanum extracted with a yield of 4.2 ± 0.7% consisted mostly of sesquiterpenes (53.8%), oxygenated sesquiterpenes (30.7%) and oxygenated monoterpenes (15,3). The main substances identified in the essential oil of P. purusanum were β-caryophyllene (57.05%), α-humulene (14.50%), germacrene D (8.20%), β-selinene (2.10%), α-selinene (4.42%), δ-cadinene (2.04%), E-nerolidol (4.23%) and caryophyllene oxide (3.46%). The essential oils of P. purusanum and P. alatipetiolatum at a concentration of 31.25 ppm inhibited the hatching of 100% of the eggs of Aedes aegypti and A. albopictus, while at the concentration of 200 ppm caused the death of 100% of larvae (LC50 from 33.74 to 62.33 ppm) and 89 and 94% of pupae (LC50 from 66.17 to 91.39 ppm) of A. aegypti and A. albopictus, respectively, at the same time that at the concentration of 125 ppm killed 100% of the larvae of Anopheles darlingi, An. triannulatus, An. nuneztovari e An. albitarsis (LC50 from 48.60 to 52.60 ppm). These activities were correlated with inhibition of AChE with inhibition percentages of 83 and 88% (IC of 2.14 and 1.94 μg/mL). In addition, essential oils also demonstrated antimicrobial activity against Enterococcus faecalis and Staphylococcus aureus with ICM from 0.5 to 125 μg/mL. The safety of essential oils was evaluated against non-target aquatic organism, Artemia salina with LC50 from 2,122.07 to 2,231.95 μg/mL. The nanoemulsions carried with the essential oils of P. alatipetiolatum (NEPa) and P. purusanum (NEPp) were constituted with nanoparticles of approximately spherical morphology with average sizes of 135 and 315.6 nm, PDI from 0.044 to 0.092, pH between 4.9 to 5.7 and zeta potential from -14.40 to - 8.51 mV. NEPa and NEPp at concentrations of 31.25 ppm inhibited 100% of eggs, while in the 25 ppm they killed 100% of the larvae (LC50 from 4.01 to 5.40 ppm) and 83 to 100% of the pupae (LC50 from 5.34 to 7.69 ppm) of A. aegypti and A. albopictus, respectively. Subsequently, 94 to 100% of Anopheles larvae died at a concentration of 25 ppm (LC50 from 3.87 to 9.81 ppm). The residual effect of the nanoemulsions was higher than the essential oils, with a percentage of 100 to 2% of larvae of A. aegypti and A. albopictus killed between the 1st and 10th day, respectively. These results demonstrate that the nanoemulsions carried with the essential oils of P. alatipetiolatum and P. purusanum are a safe tool in the control of the populations of Aedes and Anopheles