ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Essential oils are known for their insect control potential, which is mainly attributed to the presence of terpenes that interfere with hormonal and physiological processes of arthropods. The aim of the present study was to evaluate the effects of essential oil from the leaves of Eugenia sulcata Spring ex Mart., Myrtaceae, on the development of two species of agricultural pest insects, Dysdercus peruvianus and Oncopeltus fasciatus. Results showed that the essential oil induced mortality, and reduced numbers of adults. Topical treatment of Oncopeltus fasciatus using pure essential oil caused significant mortality rates (96.67%), while Dysdercus peruvianus had a higher tolerance, with 80% mortality at the end of the experiments. Results suggest that essential oil from the leaves of Eugenia sulcata may be used in agriculture for insect pest control.
ABSTRACT
Myrciaria floribunda (H. West ex Willd.) O. Berg, Myrtaceae, is popularly known as "camboim-amarelo" and was collected at Restinga de Jurubatiba (RJ, Brazil). Leaves from this species were submitted to hydrodistillation to extract its essential oil. Monoterpenes were the main compounds found (53.9%), and 1,8-cineole was the major constituent (38.4%). Studies were carried out to evaluate the effects of this essential oil on the development of two species of agricultural pests (Oncopeltus fasciatus and Dysdercus peruvianus). The essential oil was considered effective against D. peruvianus and O. fasciatus, causing mortality in both insects. The LD50 values (µg/insect) observed were 112.44 µg/insect (O. fasciatus) and 309.64 µg/insect (D. peruvianus) after one day of treatment, and 72.18 µg/insect (O. fasciatus) and 94.42 µg/insect (D. peruvianus) after 22 days of treatment. The present study reports for the first time the bioinsecticidal activity of essential oil of Myrciaria floribunda leaves, and provides important data regarding the use of essential oils in complementary programs for pest control.
ABSTRACT
Essential oils are used primarily as natural preservatives, flavourants and fragrances in cosmetic products. Several pharmacopeias possess monographs of plants which are good sources of essential oils, such as Brazilian Pharmacopeia, including Illicium verum Hook. f., Schisandraceae and Rosmarinus offi cinalis. Since determination of Hydrophile-Lipophile Balance (HLB) value of essential oils appears as a critical step for development of emulsions and other semi-solid formulations, evaluation of required HLB values for I. verum and R. offi cinalis essential oils is the aim of this study. They were obtained by hydrodistillation and several emulsions were prepared by changing emulsifiers. The couple sorbitan oleate/polysorbate 20 provided best emulsions and was used at different ratios, at a total blend concentration of 5% w/w. The lowest mean droplet diameters for R. offi cinalis and I. verum emulsions were obtained at HLB 16.5 (97.12 nm) and 16.7 (246.6 nm), respectively. Moreover, emulsions with R. offi cinalis were finer and presented some bluish reflection, characteristic of nanoemulsions. The lowest turbidity value for R. offi cinalis emulsion was also obtained at HLB 16.5 (0.33). Thus, the present study describes for the first time HLB values for R. offi cinalis (16.5) and I. verum (16.7) essential oils, contributing to their physicochemical characterization and technology development of phytopharmaceuticals.
ABSTRACT
The genus Eremanthus is recognized by the predominance of sesquiterpene lactones from the furanoheliangolide type, a class of substances extensively tested against cancer cell lines. Thus, the species E. crotonoides (DC.) Sch. Bip., Asteraceae, obtained on "restinga" vegetation was evaluated against U251 and U87-MG glioma cell lines using the MTT colorimetric assay. Dichloromethane fraction was cytotoxic to both glioblastoma multiforme cell lines. We then conducted UPLC-PDA-ESI-MS/MS analysis of the dichloromethane fraction, which allowed the identification of the sesquiterpene lactones centratherin and goyazensolide. The isolation of centratherin was performed using chromatographic techniques and the identification of this substance was confirmed according to NMR data. Cytotoxic activity of centratherin alone was also evaluated against both U251 and U87-MG cells, which showed IC50 values comparable with those obtained for the commercial anticancer drug doxorubicin. All the tested samples showed cytotoxic activity against glioblastoma multiforme cells which suggests that E. crotonoides extracts may be important sources of antiproliferative substances and that the centratherin may serve as prototype for developing new antiglioblastoma drugs.