Navegando por Autor "Barbosa, Luiz Claudio Almeida"
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Item Chemical variability and biological activities of Eucalyptus spp. essential oils(Molecules, 2016-09-07) Barbosa, Luiz Claudio Almeida; Filomeno, Claudinei Andrade; Teixeira, Robson RicardoMany plant species produce mixtures of odorous and volatile compounds known as essential oils (EOs). These mixtures play important roles in Nature and have been utilized by mankind for different purposes, such as pharmaceuticals, agrochemicals, aromatherapy, and food flavorants. There are more than 3000 EOs reported in the literature, with approximately 300 in commercial use, including the EOs from Eucalyptus species. Most EOs from Eucalyptus species are rich in monoterpenes and many have found applications in pharmaceuticals, agrochemicals, food flavorants, and perfumes. Such applications are related to their diverse biological and organoleptic properties. In this study, we review the latest information concerning the chemical composition and biological activities of EOs from different species of Eucalyptus. Among the 900 species and subspecies of the Eucalyptus genus, we examined 68 species. The studies associated with these species were conducted in 27 countries. We have focused on the antimicrobial, acaricidal, insecticidal and herbicidal activities, hoping that such information will contribute to the development of research in this field. It is also intended that the information described in this study can be useful in the rationalization of the use of Eucalyptus EOs as components for pharmaceutical and agrochemical applications as well as food preservatives and flavorants. View Full-TextItem Conformerism, enantiomorphism and double catemer motifs in para-substituted nostoclide analogues(Journal of Molecular Structure, 2016-02-15) Teixeira, Róbson Ricardo; Barbosa, Luiz Claudio Almeida; Antolinez, Isabel Valero; Corrêa, Rodrigo de Souza; Martins, Felipe Terra; Doriguetto, Antônio CarlosWe have here elucidated the crystal structures of five nostoclide analogues. A common feature in all compounds is a substituent at the para-position of the benzylidene group. Compounds with either bromine (3) or hydroxyl (4) as para-substituent crystallizes with Z’ = 2 as result of conformerism. It was also observed that Z' > 1 in the compound with a para-dimethylamino substituent (1). However, its four crystallographically independent molecules are conformationally similar. They are not related by crystallographic symmetry due to the offset packing of their C–H … OC nonclassical hydrogen bonded double chains. This compound (1) has also crystallized in a chiral space group (P21) despite the lack of a stereocenter. Such enantiomorphism phenomenon is related to the presence of only one of the two mirror benzyl conformations with phenyl ring at the equatorial position opposite the lactone oxygen atom. The molecular mean plane of nostoclide analogues has been featured by high level of planarity, except in the brominated compound where two twisted conformations occurred due to rotations on the single bond axis into benzylidene group. The benzyl conformation has been the greatest difference between the two crystallographically independent molecules of the para-hydroxylated compound (4). The crystal packing of the compounds is marked by double catemer motif assembled through C–H … OC non-classical hydrogen bonds, although C–H … π interactions do play an important role in stabilizing the crystal packing of some compounds of the series.Item Corymbia spp. and Eucalyptus spp. essential oils have insecticidal activity against Plutella xylostella(Industrial Crops and Products, 2017-12-15) Filomeno, Claudinei Andrade; Barbosa, Luiz Claudio Almeida; Teixeira, Robson Ricardo; Pinheiro, Antônio Lelis; Farias, Elizeu de Sá; Silva, Eliete Meire de Paula; Picanço, Marcelo CoutinhoPlutella xylostella (L.) is the main brassica pest worldwide and is difficult to control even with commercial insecticides. In this study, assessments were made of the contact toxicity of essential oils (EOs) from ten Myrtaceae species. For this, the leaves of four Corymbia species (C. citriodora, C. intermedia, C. maculata, and C. ptychocarpa) and six Eucalyptus species (E. andrewsii, E. crebra, E. punctata, E. pyrocarpa, E. siderophloia, and E. sphaerocarpa) were collected during the Brazilian dry season and subjected to hydrodistillation for extraction of EOs. For C. citriodora, another sample was also collected during the rainy season. The essential oil (EO) content of all samples ranged from 0.07% w/w to 3.3% w/w and GC–MS analyses allowed the identification of 52 compounds. For E. andrewsii, E. pyrocarpa, and C. ptychocarpa there was no previous report on EO chemical composition. For C. citriodora, a higher EO content for the samples collected during the dry season was found (2.72% versus 1.53% for the rainy season). The insecticidal activity of all eleven EOs was evaluated via topical application on the second-instar larvae of P. xylostella. The most active EOs were produced by C. citriodora collected during the dry season, with citronellal (86.8%) and isopulegol (4.7%) being the main constituents. At 30 μg/mg of insect, these EOs caused 80% P. xylostella mortality, being more active than neem oil used as positive control. These EOs presented low toxicity for Solenopsis saevissima, a natural predator of P. xylostella. Bioassays also demonstrated a synergistic effect between citronellal and (-)-isopulegol at all tested proportions. The results described here suggest that C. citriodora EOs can be an environmentally friendly alternative method to control P. xylostella.Item Experimental and theoretical studies on the characterization of monocrotaline by infrared and Raman spectroscopies(Journal of Molecular Structure, 2017-05-05) Oliveira, Ramon Prata; Demuner, Antonio Jacinto; Alvarenga, Elson Santiago; Parma, Monica Cropo; Barbosa, Luiz Claudio Almeida; Guimarães, Luciano de Moura; Aguiar, Alex RamosThe use of plants in folk medicine has a long and ancient history in the treatment of various diseases. Currently, a large proportion of commercial drugs are based on natural products or are synthetic compounds inspired on such natural substances. Therefore, in this communication to aid that research, structural and spectroscopic analysis of the natural pyrrolizidine alkaloid called monocrotaline was carried out. Pyrrolizidine alkaloids that are commonly found in the Boraginaceae and Asteraceae families are among the great diversity of secondary metabolites which are produced by plants to act as a defense mechanism against herbivores and microbes. In the present study, the natural product, monocrotaline, an alkaloid isolated from the leaves of Crotalaria paulina, with potential application in medicine, was characterized by infrared (IR) and Raman spectroscopy with the support of Density Functional Theory (DFT) calculations. IR and Raman spectra of monocrotaline were recorded at room temperature ranging from 4000 to 400 cm 1 . DFT calculations with the hybrid functional B3LYP and the basis set 6-31 þ G(d,p) were performed with the purpose of obtaining information on the structural and vibrational properties of this structure. A perfect fit between the experimentally measured frequencies of the IR and Raman spectra and the calculated values were observed, and we have performed the complete identification of monocrotaline by these techniques.Item A novel alkaloid isolated from Crotalaria paulina and identified by NMR and DFT calculations(Journal of Molecular Structure, 2018-02-15) Oliveira, Ramon Prata; Demuner, Antonio Jacinto; Alvarenga, Elson Santiago; Barbosa, Luiz Claudio Almeida; Silva, Thiago de MeloPyrrolizidine alkaloids (PAs) are secondary metabolites found in Crotalaria genus and are known to have several biological activities. A novel macrocycle bislactone alkaloid, coined ethylcrotaline, was isolated and purified from the aerial parts of Crotalaria paulina. The novel macrocycle was identified with the aid of high resolution mass spectrometry and advanced nuclear magnetic resonance techniques. The relative stereochemistry of the alkaloid was defined by comparing the calculated quantum mechanical hydrogen and carbon chemical shifts of eight candidate structures with the experimental NMR data. The best fit between the eight candidate structures and the experimental NMR chemical shifts was defined by the DP4 statistical analyses and the Mean Absolute Error (MAE) calculations.Item Organocatalysis in the three-component Povarov reaction and investigation by mass spectrometry(Organic & Biomolecular Chemistry, 2013-06-13) Simões, Juliana Baptista; Fátima, Ângelo de; Sabino, Adão Aparecido; Aquino, Francisco José Tôrres de; Silva, Daniel Leite da; Barbosa, Luiz Claudio Almeida; Fernandes, Sergio AntonioA diastereoselective three-component cascade reaction, catalyzed by p-sulfonic acid calix[4]arene, provides a unique method to access diverse julolidine derivatives in high yields. Additionally, the reaction was also monitored by mass spectrometry and the mechanistic pathway uncovered.Item Seasonal variation in the chemical composition and antimicrobial activity of volatile oils of three species of Leptospermum (Myrtaceae) grown in Brazil(Molecules, 2011-01-26) Demuner, Antonio Jacinto; Barbosa, Luiz Claudio Almeida; Magalhaes, Cassia Gonçalves; Silva, Cleber Jose Da; Maltha, Celia Regina Alvares; Pinheiro, Antonio LelisThis study investigates the seasonal variation of three species of Leptospermum (Myrtaceae) grown in Brazil. The chemical composition of the volatile oils of L. flavescens and L. petersonii did not show any significant seasonal variation in the major components, while for Leptospermum madidum subsp. sativum the levels of major constituents of the volatile oils varied with the harvest season. Major fluctuations in the composition of L. madidum subsp. sativum oil included α-pinene (0–15.2%), β-pinene (0.3–18.5%), α-humulene (0.8–30%), 1,8-cineole (0.4–7.1%) and E-caryophyllene (0.4–11.9%). Levels of β-pinene (0.3–5.6%), terpinen-4-ol (4.7–7.2%) and nerolidol (55.1–67.6%) fluctuated seasonally in the L. flavescens oil. In L. petersonii, changes were noted for geranial (29.8–32.8%), citronellal (26.5–33.9%) and neral (22.7–23.5%). The activity of the volatile oils against the tested bacteria differed, depending on season the oils were obtained. In general, the volatile oils were more active against Gram-positive bacteria.Item Selection of an essential oil from Corymbia and Eucalyptus plants against Ascia monuste and its selectivity to two non-target organisms(Crop Protection, 2018-08) Ribeiro, Arthur Vieira; Farias, Elizeu de Sá; Santos, Abraão Almeida; Filomeno, Claudinei Andrade; Santos, Izailda Barbosa dos; Barbosa, Luiz Claudio Almeida; Picanço, Marcelo CoutinhoDue to an increase in environmental and health issues and with the excessive use of synthetic pesticides, many studies are investigating plant essential oils (EOs) for pest control. These compounds are considered safe control agents since they have low toxicity to non-target organisms. Thus, this study aimed to select potential EOs from the Myrtaceae family and their constituents for the control of Ascia monuste (Godart) and to evaluate those EOs selectivity to two non-target organisms (Solenopsis saevissima Smith and Tetragonisca angustula Latreille). Twelve EOs, extracted by hydrodistillation from Corymbia and Eucalyptus plants, were tested in this study. All toxicity bioassays were performed by topical application. C. citriodora EO had the highest insecticidal activity against A. monuste (LD50 = 20.61 μg/mg) and also presented a fast action (LT50 < 10 min). Citronellal was the main compound of C. citriodora EO (86.8% of the oil constitution) and exhibited toxicity similar to this EO. The other compounds caused no significant mortality. Hence, the toxicity of the C. citriodora EO is mostly explained by the citronellal activity. This EO was selective in favor of the predatory ant S. saevissima but caused high mortality of the pollinator bee T. angustula. Therefore, C. citriodora EO is a promising model in the development of insecticides against A. monuste. However, to mitigate its impact over pollinators, its application must rely on the principles of ecological selectivity.Item Stink bug predator kills prey with salivary non-proteinaceous compounds(Insect Biochemistry and Molecular Biology, 2015-12-02) Martínez, Luis Carlos; Fialho, Maria do Carmo Queiroz; Barbosa, Luiz Claudio Almeida; Oliveira, Leandro Licursi; Zanuncio, José Cola; Serrão, José EduardoPodisus nigrispinus Dallas (Hemiptera: Pentatomidae) is a predator insect with potential applications in biological control because both nymphs and adults have been shown to prey on other insect pests by injection of toxic salivary gland contents. This study identified non-proteinaceous compounds with insecticidal activity from the saliva of P. nigrispinus in Anticarsia gemmatalis. In particular, the ether extract from P. nigrispinus saliva led to mortality in A. gemmatalis larvae, with a LC50 = 2.04 μL and LC90 = 3.27 μL. N,N-dimethylaniline and 1,2,5-trithiepane fractions were identified as non-proteinaceous extract components. N,N-dimethylaniline had a LC50 = 136.1 nL and LC90 = 413.8 nL, suggesting that it could be responsible for toxicity in P. nigrispinus saliva.