RESUMO
Mosquitoes can be vectors of pathogens and transmit diseases to both animals and humans. Species of the genus Culex are part of the cycle of neglected diseases, especially Culex quinquefasciatus, which is an anthropophilic vector of lymphatic filariasis. Natural products can be an alternative to synthetic insecticides for vector control; however, the main issue is the poor water availability of some compounds from plant origin. In this context, nanoemulsions are kinetic stable delivery systems of great interest for lipophilic substances. The objective of this study was to investigate the larvicidal activity of the Hyptis suaveolens essential oil nanoemulsion on Cx. quinquefasciatus. The essential oil showed a predominance of monoterpenes with retention time (RT) lower than 15 min. The average size diameter of the emulsions (sorbitan monooleate/polysorbate 20) was ≤ 200 nm. The nanoemulsion showed high larvicidal activity in concentrations of 250 and 125 ppm. CL50 values were 102.41 (77.5253−149.14) ppm and 70.8105 (44.5282−109.811) ppm after 24 and 48 h, respectively. The mortality rate in the surfactant control was lower than 9%. Scanning micrograph images showed changes in the larvae's integument. This study achieved an active nanoemulsion on Cx. quinquefasciatus through a low-energy-input technique and without using potentially toxic organic solvents. Therefore, it expands the scope of possible applications of H. suaveolens essential oil in the production of high-added-value nanosystems for tropical disease vector control.
Assuntos
Aedes , Culex , Culicidae , Inseticidas , Lamiaceae , Óleos Voláteis , Humanos , Animais , Óleos Voláteis/farmacologia , Óleos Voláteis/análise , Larva , Mosquitos Vetores , Inseticidas/química , Extratos Vegetais/química , Folhas de Planta/químicaRESUMO
ABSTRACT Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson, Verbenaceae, is considered a great source of a bioactive volatile oil. Due to the wide range of known chemotypes, its chemical analysis is very important. Among the several activities of this volatile oil, a potential larvicidal action against Culicidae species is highlighted. However, the low water miscibility of volatile oils limits their application in aqueous media. Oil in water nano-emulsions are in the spotlight of novelty to solve this main problem. Thus, the aim of the present study was to obtain this nanostructured system with L. alba volatile oil (citral chemotype) and evaluate its larvicidal activity against Aedes aegypti and Culex quinquefasciatus larvae. The major compounds were geranial (30.02%) and neral (25.26%). Low mean droplet size (117.0 ± 1.0 nm) and low polydispersity index (0.231 ± 0.004) were observed and no major changes were observed after seven days of storage. LC50 values against C. quinquefasciatus and A. aegypti third-instar larvae were respectively 38.22 and 31.02 ppm, while LC90 values were, respectively, 59.42 and 47.19 ppm. The present study makes use of a low energy, solvent-free and ecofriendly method with reduced costs. Thus, this paper contributes significantly to phyto-nanobiotechnology of larvicidal agents, opening perspectives for the utilization of L. alba volatile oil in integrated practices of vector control.
Assuntos
Antioxidantes/uso terapêutico , Doenças Metabólicas/prevenção & controle , Doenças Neurodegenerativas/prevenção & controle , Ácido Ascórbico/uso terapêutico , Carotenoides/uso terapêutico , Suplementos Nutricionais , Humanos , Doenças Metabólicas/metabolismo , Doenças Metabólicas/patologia , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Polifenóis/uso terapêuticoRESUMO
Andiroba (Carapa guianensis) seeds are the source of an oil with a wide range of biological activities and ethnopharmacological uses. However, few studies have devoted attention to innovative formulations, including nanoemulsions. The present study aimed to obtain a colloidal system with the andiroba oil using a low-energy and organic-solvent-free method. Moreover, the preliminary residual larvicidal activity of the nanoemulsion against Aedes aegypti was evaluated. Oleic and palmitic acids were the major fatty acids, in addition to the phytosterol ß-sitosterol and limonoids (tetranortriterpenoids). The required hydrophile-lipophile was around 11.0 and the optimal nanoemulsion was obtained using polysorbate 85. The particle size distribution suggested the presence of small droplets (mean diameter around 150 nm) and low polydispersity index (around 0.150). The effect of temperature on particle size distribution revealed that no major droplet size increase occurred. The preliminary residual larvicidal assay suggested that the mortality increased as a function of time. The present study allowed achievement of a potential bioactive oil in water nanoemulsion that may be a promising controlled release system. Moreover, the ecofriendly approach involved in the preparation associated with the great bioactive potential of C. guianensis makes this nanoemulsion very promising for valorization of this Amazon raw material.
RESUMO
Abstract Pterodon emarginatus Vogel, Fabaceae, is a great source of bioactive compounds. The most known and studied herbal derivative from this species is an ambar-colored oleoresin that contains vouacapane diterpenes and volatile terpenoids, such as β-caryophyllene. Some recent papers aimed to generate nanoemulsions using this oleoresin for biological applications. However, they used high-energy methods that elevate costs of the process or heating procedures, which offer the disadvantage of possible volatile substances loss. Thus, as part of our ongoing studies with nanobiotechnology of natural products, especially regarding preparation of nanoemulsions with promising plant-based oils by low cost and low energy methods, we decided to evaluate the ability of non-heating and solvent-free method to generate P. emarginatus oleoresin-based nanoemulsions. Two non-ionic surfactants were used to generate the nanoemulsions by a simple homogenization method with vortex stirrer. Low mean droplet size (<180 nm) and low polydispersity index (<0.200) were observed even after one day of preparation. The low coefficient of variation for the analyzed parameters of different batches and similar profile for droplet size distribution suggested reproducibility of the method. After 30 days, some degree of droplet growth was observed on nanoemulsion prepared with polyethyleneglycol 400 monooleate, while almost no alteration was observed for nanoemulsion prepared with polysorbate 85. Programmed temperature ramp analysis revealed that no major effects on droplet size and polydispersity index were observed, suggesting the robustness of formed nanoemulsions. Thus, the present study shows for the first time the formation of sucupira-based nanoemulsions by a simple, low cost and ecofriendly method. This study opens new perspectives for bioactive evaluation of this novel nano-product.
RESUMO
BACKGROUND: Preparation of nanoformulations using natural products as bioactive substances is considered very promising for innovative larvicidal agents. On this context, oil in water nanoemulsions develop a main role, since they satisfactorily disperse poor-water soluble substances, such as herbal oils, in aqueous media. Pterodon emarginatus, popularly known as sucupira, has a promising bioactive oleoresin. However, to our knowledge, no previous studies were carried out to evaluate its potential against Culex quinquefasciatus, the main vector of the tropical neglected disease called lymphatic filariasis or elephantiasis. Thus, we aimed to investigate influence of different pairs of surfactants in nanoemulsion formation and investigate if a sucupira oleoresin-based nanoemulsion has promising larvicidal activity against this C. quinquefasciatus. We also evaluated morphological alteration, possible mechanism of insecticidal action and ecotoxicity of the nanoemulsion against a non-target organism. RESULTS: Among the different pairs of surfactants that were tested, nanoemulsions obtained with polysorbate 80/sorbitan monooleate and polysorbate 80/sorbitan trioleate presented smallest mean droplet size just afterwards preparation, respectively 151.0 ± 2.252 and 160.7 ± 1.493 nm. They presented high negative zeta potential values, low polydispersity index (<0.300) and did not present great alteration in mean droplet size and polydispersity index after 1 day of preparation. Overall, nanoemulsion prepared with polysorbate 80/sorbitan monooleate was considered more stable and was chosen for biological assays. It presented low LC50 value against larvae (34.75; 7.31-51.86 mg/L) after 48 h of treatment and some morphological alteration was observed. The nanoemulsion did not inhibit acetylcholinesterase of C. quinquefasciatus larvae. It was not toxic to green algae Chlorella vulgaris at low concentration (25 mg/L). CONCLUSIONS: Our results suggest that optimal nanoemulsions may be prepared with different surfactants using a low cost and low energy simple method. Moreover, this prototype proved to be effective against C. quinquefasciatus, being considered an ecofriendly novel nanoproduct that can be useful in integrated control programs of vector control.
Assuntos
Culicidae/efeitos dos fármacos , Emulsões/toxicidade , Fabaceae/química , Controle de Insetos , Inseticidas/toxicidade , Extratos Vegetais/toxicidade , Animais , Chlorella vulgaris/efeitos dos fármacos , Chlorella vulgaris/fisiologia , Culicidae/fisiologia , Emulsões/química , Feminino , Inseticidas/química , Larva/efeitos dos fármacos , Larva/fisiologia , Extratos Vegetais/químicaRESUMO
Pterodon emarginatus Vogel is a Brazilian species that belongs to the family Fabaceae, popularly known as sucupira. Its oil has several biological activities, including potent larvicidal property against Aedes aegypti. This insect is the vector of dengue, a tropical disease that has been considered a critical health problem in developing countries, such as Brazil. Most of dengue control methods involve larvicidal agents suspended or diluted in water and making active lipophilic natural products available is therefore considered a technological challenge. In this context, nanoemulsions appear as viable alternatives to solve this major problem. The present study describes the development of a novel nanoemulsion with larvicidal activity against A. aegypti along with the required Hydrophile Lipophile Balance determination of this oil. It was suggested that the mechanism of action might involve reversible inhibition of acetylcholinesterase and our results also suggest that the P. emarginatus nanoemulsion is not toxic for mammals. Thus, it contributes significantly to alternative integrative practices of dengue control, as well as to develop sucupira based nanoproducts for application in aqueous media.
Assuntos
Aedes/efeitos dos fármacos , Fabaceae/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Nanoestruturas/química , Óleos Voláteis/farmacologia , Acetilcolinesterase/metabolismo , Aedes/enzimologia , Aedes/crescimento & desenvolvimento , Animais , Comportamento Animal/efeitos dos fármacos , Dengue/prevenção & controle , Emulsões , Feminino , Interações Hidrofóbicas e Hidrofílicas , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/metabolismo , Inseticidas/isolamento & purificação , Larva/enzimologia , Larva/crescimento & desenvolvimento , Dose Letal Mediana , Camundongos , Controle de Mosquitos/métodos , Óleos Voláteis/isolamento & purificação , Extratos Vegetais/química , Folhas de Planta/químicaRESUMO
Copaiba (Copaifera duckei Dwyer, Fabaceae) oleoresin is an important Amazonian raw material. Despite its insecticidal potential, poor water solubility remains a challenge for the development of effective and viable products. Nanotechnology has emerged as a promising area to solve this problem, especially oil-in-water nanoemulsions. On this context, the aim of the present study was to develop oil-in-water nanoemulsions using copaiba oleoresin dispersed through a high internal phase; and evaluate its potential insecticidal action against Aedes aegypti larvae. Overall, 31 formulations were prepared, ranging from 11.5 ± 0.2 to 257.3 ± 4.1 nm after one day of manipulation. Some of them reached small mean droplet sizes (< 200 nm) and allowed achievement of a nanoemulsion region. The formulation consisted of 5% (w/w) of copaiba oil, 5% (w/w) of surfactant and 90% (w/w) of water, which presented mean droplet size of 145.2 ±0.9 nm and polidispersity of 0.378 ± 0.009 after one day of manipulation, and these were evaluated for larvicidal potential. According to mortality level (250 ppm - 93.3 after 48 h), this nanoemulsion was classified as a promising insecticidal agent against Aedes aegypti larvae. The present study allowed the development of low-cost ecofriendly green natural-based nanoformulations with potential larvicidal activity, using a nanobiotechnology approach.
RESUMO
Manilkara subsericea (Mart.) Dubard (Sapotaceae) is popularly known in Brazil as "guracica." Studies with Manilkara spp indicated the presence of triterpenes, saponins, and flavonoids. Several activities have been attributed to Manilkara spp such as antimicrobial, antiparasitic and antitumoral, which indicates the great biological potential of this genus. In all, 87.19% of the hexanic extract from fruits relative composition were evaluated, in which 72.81% were beta- and alpha-amyrin esters, suggesting that they may be chemical markers for M. subsericea. Hexadecanoic acid, hexadecanoic acid ethyl ester, (E)-9-octadecenoic acid ethyl ester, and octadecanoic acid ethyl ester were also identified. Ethanolic crude extracts from leaves, stems, and hexanic extract from fruits exhibited antimicrobial activity against Staphylococcus aureus ATCC25923. These extracts had high IC50 values against Vero cells, demonstrating weak cytotoxicity. This is the first time, to our knowledge, that beta- and alpha-amyrin caproates and caprylates are described for Manilkara subsericea.
Assuntos
Ésteres/química , Manilkara/química , Triterpenos/química , Animais , Antibacterianos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Chlorocebus aethiops , Frutas/química , Concentração Inibidora 50 , Ácido Palmítico/análise , Extratos Vegetais/farmacologia , Staphylococcus aureus/metabolismo , Ácidos Esteáricos/análise , Células VeroRESUMO
Neomitranthes obscura (DC.) N. Silveira is an endemic plant of Brazilian Atlantic Forest and widely spread in the sandbanks of "Restinga de Jurubatiba" National Park. It is popularly known by local population as "camboim-de-cachorro" or "cambuí-preto" and recognized by its black ripe fruits. However, specimens with yellow ripe fruits were localized in the "Restinga de Jurubatiba" National Park. The aim of the present study was to evaluate chemical composition of essential oils obtained from leaves and fruits of N. obscura specimens with different fruit color (black and yellow) by GC and GC-MS. Essential oils from leaves of specimens with black and yellow fruits indicated a predominance of sesquiterpenes (81.1% and 84.8%, resp.). Meanwhile, essential oil from black fruits presented a predominance of monoterpenes (50.5%), while essential oil from yellow fruits had sesquiterpenes (39.9%) as major substances. Despite previous studies about this species, including essential oil extraction, to our knowledge this is the first report on N. obscura fruits with different colors. Our results suggest the occurrence of unless two different varieties for this species.