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Efeito larvicida de extratos aquosos de resíduos de café, em três espécies de Anopheles (Diptera, Culicidae)
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A (re) emergência de doenças transmitidas por mosquitos, tais como as filarioses e as arboviroses (e.g. dengue), é atualmente, um dos maiores problemas de saúde a nível mundial, devido à elevada mortalidade e morbilidade que estas patologias causam, especialmente, em regiões tropicais e subtropicais, onde o acesso a sistemas de saúde é deficitário. O uso de inseticidas continua a ser uma das estratégias mais utilizada no controlo dos insetos vetores destas doenças, contudo, devido ao uso excessivo destes químicos, os níveis de resistência dos mosquitos aos inseticidas têm vindo a aumentar. Assim, é necessário pôr em prática novas estratégias para reduzir as populações de vetores de forma sustentável e economicamente viável, especialmente, em países em desenvolvimento.
Neste trabalho avaliou-se o efeito larvicida de extratos obtidos a partir de resíduos provenientes da indústria de café. Neste estudo recorreu-se a uma tecnologia de elevada sustentabilidade e inovadora na sua aplicação a esta problemática: a tecnologia de separação de componentes por membranas.
Com base nesta tecnologia foram obtidos de extratos enriquecidos em compostos fenólicos, particularmente, cafeína (CAF) e ácido clorogénico (CGA). Inicialmente, otimizou-se as condições extração (temperatura, o tempo de extração e meio de solvente). De seguida, avaliou-se os parâmetros de rejeição e valores de permeabilidade de diferentes membranas de ultrafiltração e nanofiltração na obtenção de frações enriquecidas dos compostos em estudo. E por fim, os extratos brutos e fracionados foram concentrados por evaporação a vácuo num rotavapor.
As concentrações obtidas para o extrato bruto concentrado foram de 2727, 763 e 797 mg.L-1, de fenólicos totais, CAF e CGA, respetivamente. Para o extrato fracionado após concentração foram encontrados valores de 2267, 730 e 553 mg.L-1, de fenólicos totais, CAF e CGA, respetivamente.
Com os extratos brutos e fracionados concentrados efetuaram-se bioensaios padronizados OMS de sensibilidade aos inseticidas em larvas de 3º/4º estado de Anopheles gambiae Gilles, 1972, Anopheles stephensi Liston, 1901 e Anopheles atroparvus Van Thiel, 1927, respetivamente, o principal vetor de malária em Africa e Ásia, e, o antigo vetor desta doença na Europa. As mortalidades ocorridas com o extrato bruto concentrado foram de 100% para An. gambiae e An. stephensi e de 96% para An. atroparvus. Com o extrato fracionado concentrado, as mortalidades foram de 99%, 95% e de 54% para An. gambiae, An. stephensi e An. atroparvus, respetivamente.
Foram ainda realizados bioensaios de dose-resposta para An. gambiae com o extrato mais eficaz, com os quais se determinou as seguintes concentrações letais (LC), LC50 de 140 g/L, LC90 de 310 g/L e LC99 de 580 g/L.
Com estes ensaios preliminares, conclui-se que extratos obtidos do reaproveitamento de resíduos de café podem ser uma promissora alternativa aos inseticidas atuais, porém, a metodologia utilizada necessita de algum melhoramento para a obtenção de extratos mais concentrados e consequentemente com maior efeito larvicida.
The (re)emergence vector-borne diseases, as filariosis and arboviruses (e.g dengue) is currently major global health problem, particularly in tropical and sub-tropical areas where access to health care is scarce. Insecticides remains the principal strategy in the control of vector-borne diseases, however, due to the overuse of these chemicals, the insecticide resistance of mosquitos has been increasing in last years. Thus, the implementation of new, sustainable and economically viable strategies to reduce vector populations are necessary, especially in low-rent countries. The main propose of this work was to evaluation the larvicidal effects of extracts attained from coffee industry residues. These extracts were obtained through an innovative application of a known sustainable technology: the separation of compounds by membranes. The objective was to obtain extracts enriched in phenolic compounds, namely caffeine (CAF), and chlorogenic acid (CGA) based on this technology. Initially were optimized several extraction conditions (extraction temperature, extraction time and extracting medium). Subsequently, parameters of rejection of these phenolic compounds and permeability values of different ultrafiltration and nanofiltration membranes were assessed in the achievement fractionated extracts enriched in phenolics compounds of interest. Lastly, crude and fractionated extracts were concentrated by evaporation in a rotary evaporator. The concentration levels for the concentrated crude extract were 2727, 763 and 797 mg L-1 of total phenolics compounds, CAF and CGA, respectively. In fractionated and concentrated extract, recovered values obtained were 2267, 730 and 553 mg L-1, total phenolics compounds, CAF and CGA, respectively, of concentration levels. Bioassays larvicidal was performed with concentrated crude and fractionated extracts through WHO standardized bioassays to insecticides in larvae of the 3rd/4th instar of Anopheles gambiae Gilles, 1972, Anopheles stephensi Liston, 1901 and Anopheles atroparvus Van Thiel, 1927, respectively, the main vector of malaria in Africa and Asia, and the former vector of this endemic disease in Europe. The mortalities occurred with the concentrated crude extract were 100% for An. gambiae and An. stephensi and 96% to An. atroparvus. With the concentrated extract fractionated mortalities were 99%, 95% and 54% for An. gambiae, An. stephensi and An. atroparvus, respectively. Also were carried out dose-response bioassays in An. gambiae with the most effective extract, wherein the following lethal concentrations (LC) were determined, LC50 140 g.L-1, LC90 310 g.L-1 and LC99 of 580 g.L-1. These preliminary tests, showed that extracts reusing coffee residues may be a promising alternative to current pesticides, however, the methodology needs some improvement for obtaining more concentrated extracts and consequently more larvicidal effect.
The (re)emergence vector-borne diseases, as filariosis and arboviruses (e.g dengue) is currently major global health problem, particularly in tropical and sub-tropical areas where access to health care is scarce. Insecticides remains the principal strategy in the control of vector-borne diseases, however, due to the overuse of these chemicals, the insecticide resistance of mosquitos has been increasing in last years. Thus, the implementation of new, sustainable and economically viable strategies to reduce vector populations are necessary, especially in low-rent countries. The main propose of this work was to evaluation the larvicidal effects of extracts attained from coffee industry residues. These extracts were obtained through an innovative application of a known sustainable technology: the separation of compounds by membranes. The objective was to obtain extracts enriched in phenolic compounds, namely caffeine (CAF), and chlorogenic acid (CGA) based on this technology. Initially were optimized several extraction conditions (extraction temperature, extraction time and extracting medium). Subsequently, parameters of rejection of these phenolic compounds and permeability values of different ultrafiltration and nanofiltration membranes were assessed in the achievement fractionated extracts enriched in phenolics compounds of interest. Lastly, crude and fractionated extracts were concentrated by evaporation in a rotary evaporator. The concentration levels for the concentrated crude extract were 2727, 763 and 797 mg L-1 of total phenolics compounds, CAF and CGA, respectively. In fractionated and concentrated extract, recovered values obtained were 2267, 730 and 553 mg L-1, total phenolics compounds, CAF and CGA, respectively, of concentration levels. Bioassays larvicidal was performed with concentrated crude and fractionated extracts through WHO standardized bioassays to insecticides in larvae of the 3rd/4th instar of Anopheles gambiae Gilles, 1972, Anopheles stephensi Liston, 1901 and Anopheles atroparvus Van Thiel, 1927, respectively, the main vector of malaria in Africa and Asia, and the former vector of this endemic disease in Europe. The mortalities occurred with the concentrated crude extract were 100% for An. gambiae and An. stephensi and 96% to An. atroparvus. With the concentrated extract fractionated mortalities were 99%, 95% and 54% for An. gambiae, An. stephensi and An. atroparvus, respectively. Also were carried out dose-response bioassays in An. gambiae with the most effective extract, wherein the following lethal concentrations (LC) were determined, LC50 140 g.L-1, LC90 310 g.L-1 and LC99 of 580 g.L-1. These preliminary tests, showed that extracts reusing coffee residues may be a promising alternative to current pesticides, however, the methodology needs some improvement for obtaining more concentrated extracts and consequently more larvicidal effect.
Descrição
Palavras-chave
Saúde pública Anopheles Diptera, culicidae Cafeina Tecnologias de membranas Larvicidas Culicidae
Contexto Educativo
Citação
Editora
Instituto de Higiene e Medicina Tropical