Nanopartículas lipídicas sólidas como sistemas carreadores de extrato de piretro e avaliação toxicológica em organismos não-alvos
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Data
2019-08-23
Autores
Oliveira, Cristiane Ronchi de
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Universidade Estadual Paulista (Unesp)
Resumo
O extenso crescimento da agricultura combinado com o uso intensivo de agrotóxicos tem causado preocupação com a manutenção dos ecossistemas e a produção de alimentos realmente saudáveis. Atualmente, têm-se buscado alternativas sustentáveis para produção agrícola como os inseticidas botânicos e nanopesticidas. Os inseticidas botânicos são extraídos de plantas e utilizados no controle de pragas, sendo estes considerados biodegradáveis, seguros e menos tóxicos para a biodiversidade. Eles podem ser encapsulados em nanocarreadores que aumentam sua estabilidade e otimizem o seu uso agrícola. Os nanopesticidas trazem benefícios para o ambiente e a produtividade agrícola, dos quais destacam-se a liberação modificada dos ingredientes ativos nos campos agrícolas, maior estabilidade do sistema, menor toxicidade aos seres vivos e redução do impacto ambiental. No entanto, percebe-se a necessidade de estudos de toxicidade dos inseticidas botânicos e dos nanopesticidas em organismos não-alvos, como abelhas e anfíbios que estão declinando rapidamente no mundo inteiro. O objetivo desse estudo foi preparar e caracterizar os sistemas carreadores do extrato de piretro e avaliar o efeito destes compostos em girinos de rã-touro (Lithobates catesbeianus) e abelhas (Apis mellifera Africanizada), utilizando biomarcadores de diferentes tipologias em nível subindividual e de indivíduo. O extrato de piretro encapsulado em nanopartículas (NLS+PIR) evidenciaram uma boa estabilidade físico-química em função do tempo e uma pequena distribuição no diâmetro das partículas, com um diâmetro hidrodinâmico médio de 257,6 ± 2,0 nm, polidispersão média de 0,11 ± 0,01 e eficiência de encapsulação maior que 99%. Nos bioensaios de toxicidade com abelhas observou-se menor índice total de lesão do intestino médio nos indivíduos do grupo NLS+PIR em relação aos grupos expostos a nanopartículas lipídicas sólidas (NLS; 7,4 ± 0,5) e ao extrato de piretro (PIR10ng; 7,4 ± 0,8). O tempo de sobrevivência das abelhas expostas ao inseticida botânico (PIR10ng = 141,18 ± 21,3 h) e ao piretróide (DLT10ng = 25,33 ± 0,93 h) foram significativamente menores quando comparados ao controle (257,83 ± 21,79 h). Entretanto, nos bioensaios com os girinos de rã-touro as NLS+PIR causaram alterações nos parâmetros hematológicas, com um aumento na quantidade de eosinófilos e eritrócitos, nas anormalidades nucleares eritrocíticas e danos no DNA, bem como desencadeado efeito hepatológicos como um aumento na congestão sinusoidal e na infiltração eosinofílica, e uma maior quantidade de células melanomacrofágicas. No índice total de lesão no fígado todos os grupos expostos (NLS, NLS+PIR, PIR e PVA) evidenciaram um aumento significativo em relação ao controle (P < 0,0001), contudo a exposição ao piretro encapsulado em nanopartículas (NLS+PIR) demonstrou o maior índice total da lesão no órgão (43,6 ± 2,7). Portanto, os dados demonstram a importância de se compreender melhor a toxicidade dos inseticidas botânicos e nanopesticidas, o que é importante para avaliação toxicológica e de monitoramento ambiental. O desenvolvimento de formulações alternativas, como os nanopesticidas, para o controle de pragas na agricultura, contribuem para a sustentabilidade agrícola e, portanto, devem ser avaliados quanto a sua toxicidade nos organismos não-alvos a fim de auxiliar na compreensão nanotoxicológica e na proposição de legislações e regulamentações para o seu uso no campo.
The extensive growth of agriculture combined with the intensive use of agricultural pesticides has caused concern for the maintenance of ecosystems and the production of truly healthy food. Sustainable alternatives for agricultural production such as botanical insecticides and nanopesticides have been sought nowadays. Botanic insecticides used in pest control are extracted from plants, hence they are considered biodegradable, safe and less toxic to biodiversity. They can be encapsulated in nanocarriers that increase their stability and optimize their agricultural use. Nanopesticides bring both benefits to the environment and agricultural productivity, such as the modified release of active ingredients in agricultural fields, greater system stability, less toxicity to living beings and environmental impact reduction. However, there is a need for toxicity studies of botanical insecticides and nanopesticides in non-target organisms such as bees and amphibians that are rapidly declining throughout the world. The objective of this study was to prepare and characterize the pyrethrum extract carrier systems and to evaluate the effect of these compounds on tadpoles (Lithobates catesbeianus) and bees (Africanized Apis mellifera) using biomarkers of different types at the subindividual and individual levels. The nanoparticle-encapsulated pyrethrum extract (SLN+PYR) showed good physico-chemical stability as a function of time and a small particle diameter distribution with a mean hydrodynamic diameter of 257.6 ± 2.0 nm, mean polydispersity of 0.11 ± 0.01 and encapsulation efficiency greater than 99%. In the toxicity bioassays with bees, the lowest intestinal lesion total index in the SLN+PYR group was observed in relation to the groups exposed to solid lipid nanoparticles (SLN, 7.4 ± 0.5) and pyrethrum extract (PYR10ng, 7.4 ± 0.8). The survival time of bees exposed to the botanical insecticide (PYR10ng = 141.18 ± 21.3 h) and to the pyrethroid (DLT10ng = 25.33 ± 0.93 h) were significantly lower when compared with control group (257.83 ± 21,79 h). However, the SLN+PYR caused changes in hematological parameters in the bioassays with bullfrog tadpoles, an increase in the number of eosinophils and erythrocytes, erythrocytic nuclear abnormalities and DNA damage, as well as triggering hepatological effects such as increased sinusoidal congestion, eosinophilic infiltration and a greater amount of melanomorphagic cells. All exposed groups (SLN, SLN+PYR, PYR and PVA) demonstrated a significant increase in liver lesion total index in compared to control (P < 0.0001), however the exposure to the nanoparticle encapsulated pyrethrum showed the highest total injury in the organ (43.6 ± 2.7). Therefore, the data demonstrate the importance of better understanding the toxicity of botanical insecticides and nanopesticides, which is important for toxicological assessment and environmental monitoring. The development of alternative formulations for pest control in agriculture, such as nanopesticides, contributes to agricultural sustainability and should therefore be evaluated for their toxicity in non-target organisms in order to assist in nanotoxicological understanding and in proposing legislation and regulations for its use in the field.
The extensive growth of agriculture combined with the intensive use of agricultural pesticides has caused concern for the maintenance of ecosystems and the production of truly healthy food. Sustainable alternatives for agricultural production such as botanical insecticides and nanopesticides have been sought nowadays. Botanic insecticides used in pest control are extracted from plants, hence they are considered biodegradable, safe and less toxic to biodiversity. They can be encapsulated in nanocarriers that increase their stability and optimize their agricultural use. Nanopesticides bring both benefits to the environment and agricultural productivity, such as the modified release of active ingredients in agricultural fields, greater system stability, less toxicity to living beings and environmental impact reduction. However, there is a need for toxicity studies of botanical insecticides and nanopesticides in non-target organisms such as bees and amphibians that are rapidly declining throughout the world. The objective of this study was to prepare and characterize the pyrethrum extract carrier systems and to evaluate the effect of these compounds on tadpoles (Lithobates catesbeianus) and bees (Africanized Apis mellifera) using biomarkers of different types at the subindividual and individual levels. The nanoparticle-encapsulated pyrethrum extract (SLN+PYR) showed good physico-chemical stability as a function of time and a small particle diameter distribution with a mean hydrodynamic diameter of 257.6 ± 2.0 nm, mean polydispersity of 0.11 ± 0.01 and encapsulation efficiency greater than 99%. In the toxicity bioassays with bees, the lowest intestinal lesion total index in the SLN+PYR group was observed in relation to the groups exposed to solid lipid nanoparticles (SLN, 7.4 ± 0.5) and pyrethrum extract (PYR10ng, 7.4 ± 0.8). The survival time of bees exposed to the botanical insecticide (PYR10ng = 141.18 ± 21.3 h) and to the pyrethroid (DLT10ng = 25.33 ± 0.93 h) were significantly lower when compared with control group (257.83 ± 21,79 h). However, the SLN+PYR caused changes in hematological parameters in the bioassays with bullfrog tadpoles, an increase in the number of eosinophils and erythrocytes, erythrocytic nuclear abnormalities and DNA damage, as well as triggering hepatological effects such as increased sinusoidal congestion, eosinophilic infiltration and a greater amount of melanomorphagic cells. All exposed groups (SLN, SLN+PYR, PYR and PVA) demonstrated a significant increase in liver lesion total index in compared to control (P < 0.0001), however the exposure to the nanoparticle encapsulated pyrethrum showed the highest total injury in the organ (43.6 ± 2.7). Therefore, the data demonstrate the importance of better understanding the toxicity of botanical insecticides and nanopesticides, which is important for toxicological assessment and environmental monitoring. The development of alternative formulations for pest control in agriculture, such as nanopesticides, contributes to agricultural sustainability and should therefore be evaluated for their toxicity in non-target organisms in order to assist in nanotoxicological understanding and in proposing legislation and regulations for its use in the field.
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Palavras-chave
Nanopartículas, Piretróides, Toxicologia, Abelhas, Anfíbio, Nanoparticles, Pyrethroids, Toxicology, Bees, Amphibians