Licenciatura em Química (Sede)

URI permanente desta comunidadehttps://arandu.ufrpe.br/handle/123456789/26

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Análise da composição química do óleo essencial de espécies de Plectranthus cultivadas sob condições de estresse e avaliação Do seu potencial acaricida sobre o Tetranychus urticae
(2024-07-31) Silva, Beatriz Steffanie Gomes da; Moraes, Marcílio Martins de; http://lattes.cnpq.br/6957579091162269; http://lattes.cnpq.br/4696332206790980
Plants are living organisms capable of producing secondary metabolites as a defense and development mechanism. What stimulates the activation of secondary metabolism are changes in the natural conditions necessary for the survival of the plant, called biotic or abiotic stresses. Essential oils (EOs) are complex mixtures of constituents originating from the secondary metabolism of plants, and have different biological properties, from medicinal purposes to pest control. Thus, the objective of this study was to investigate the variation in the chemical composition of EOs from two species of the genus Plectranthus (P. barbatus and P. ornatus) under controlled stress conditions and the antioxidant and acaricidal potential against Tetranychus urticae (spotted spider mite). The species were separated into groups and subjected to different stress conditions: manual predation (PM), methyl salicylate (SM), methyl jasmonate (MJ), saline (S), water scarcity (E), ultraviolet radiation (UV), and the group without any stress (control). The EOs were obtained by hydrodistillation and the chemical composition was determined by gas chromatography coupled to mass spectrum (GC-MS). The data were subjected to multivariate analyses (PCA, heatmap and molecular network). The acaricidal activity was evaluated comparatively through the LC90 of the positive control Azamax and the antioxidant activity by the ABTS.+ and DPPH methods. For both species, the chemical composition identified in the control groups showed a predominance of constituents derived from sesquiterpenes, with (E)- caryophyllene as the major constituent. However, in the stressed groups, monoterpenes were present in higher percentages, significantly reducing the percentage of the major compound of the control. This variation was confirmed by all multivariate analyses used. The EOs of both species showed low acaricidal activity against the two-spotted spider mite, with mortality rates equal to 12.00% (P. barbatus) and 22.72% (P. ornatus). P. barbatus showed better antioxidant activity for ABTS.+ (62.74 μg/ml) while P. ornatus showed better for DPPH. (163.5 μg/ml). However, compared to the positive controls Trolox (4.13 μg/ml) and ascorbic acid (1.62 μg/ml), respectively, the activities presented by both species were relatively low. Therefore, it was possible to verify that the EOs of these species present antioxidant and acaricidal activities, although low, and that different stress conditions alter the chemical composition of the plant.
Composição química e atividade acaricida do óleo essencial das folhas de Syzygium cumini (Myrtaceae)
(2021-07-15) Almeida, Alice Mariana Souza de; Camara, Cláudio Augusto Gomes da; http://lattes.cnpq.br/5615678215435460; http://lattes.cnpq.br/5370687315044618
Syzygium cumini, known as purple olive, or jamul, dates back to its healing powers since the beginnings of many societies, today confirmed through its antioxidant, anti-diabetic, anti-fungal properties and reports against different arthropods. The essential oil, extracted from the fresh leaves, through hydrodistillation technique with the aid of a Clevenger type apparatus, had a yield of 0.12%m/m and its chemical characterization, through Gas Chromatography coupled to a Mass Spectrometer (GC-MS), provided as major constituents (Z)-[beta]-ocimene (30.456%), [alfa]-pinene (15.537%) and (E)-[beta]-ocimene (15.177%). The contact bioassays performed, with the objective of identifying the effects of the oil on the spider mite, demonstrated a considerable toxicity of the oil. The residual contact bioassay, which the mites are placed on already treated leaves, presented the LC50 = 7.54uL/mL. While in the spray bioassay, where the mites are sprayed when they are on the leaves, presented a LC50 = 8.69uL/mL. In addition, the oil was also showed an ovicidal property with an estimated LC50 of 0.22uL/mL. this essential oilvshowed similar and promising effects compared to acaricides already marketed, while bioassaysvdemonstrated how different tests act on pest instinct mechanisms.
Composição química, atividade acaricida, propriedade antioxidante, inibição da acetilcolinesterase e toxicidade do óleo essencial das folhas de Sparattanthelium botocudorum
(2024-03-05) Silva, Mirian Luzinete da; Camara, Cláudio Augusto Gomes da; http://lattes.cnpq.br/5615678215435460; http://lattes.cnpq.br/4499498152298785
Sparattanthelium botocudorum is a species endemic to Brazil, commonly known as “Canela-brava”, this shrub is distributed on the coast of Paraíba and in the state of Pernambuco. Due to the scarcity of chemical and biological studies on this plant, the research aimed to determine the chemical composition of the essential oil of the leaves as well as the evaluation of the acaricidal, antioxidant and toxicity properties against Artemia salina. The essential oil, extracted from fresh leaves, through the hydrodistillation technique with the aid of a Clevenger-type device, had a yield of 0.40% m/m and its chemical characterization, through Gas Chromatography coupled to the Mass Spectrometer (CG-MS), emerged as the majority constituents were the sesquiterpenes Germanecrene D with (38.28 %), E-Nerolidol (18.95 %), [beta]-Caryophyllene (14.49 %) and Biciclogermacrene (14.18 %) and the single monoterpene Z-[beta]-Ocimene identified in the OE with a percentage of 0.37%. Residual contact bioassays were carried out, with the aim of identifying the effects of the oil on the two-spotted mite, and showed promising toxicity. The residual contact bioassay, in which the mites are arranged on already treated leaves, showed LC50 = 16.5 μL/mL. Furthermore, the oil also demonstrated ovicidal properties with an estimated LC50 of 1.20 μL/mL. And regarding repellency activity, the oil showed a better potential with the LC30 concentration 8.8 μL/mL. After evaluating the inhibition activity of the acetylcholinesterase enzyme, the essential oil from the leaves of S. botocudorum inhibited the enzyme, since the LC50 resulted was 2.9 μg/mL below the LC50 of the positive control, which is 5.95 μg/mL. mL. Furthermore, OE presented antioxidant properties for the free radical DPPH˙, estimating an EC50 = 110.3 μg/mL, while for the free radical ABTS˙+ it was EC50 = 49.23 μg/mL. Finally, the oil exhibited a toxicity concentration of 700 μg/mL for the toxicity test against A. salina, which compared to what described in the literature had no toxicity. Therefore, the study showed that the essential oil presented similar and promising effects compared to already commercialized acaricides, and that the bioassays presented different routes of action, therefore acting with different mechanisms on the pest and presenting a biological property of antioxidant activity.
Composição química, atividade citotóxica, acaricida e antioxidante do óleo essencial das flores de Caesalpinia echinata (Pau-brasil)
(2021-12-10) Rodrigues, Lucas Vitor Batista; Camara, Cláudio Augusto Gomes da; http://lattes.cnpq.br/5615678215435460; http://lattes.cnpq.br/7934872766687903
Belonging to the family Fabaceae, Caesalpinia echinata is a tree endemic to Brazil, popularly known as pau-brasil. It was widely explored because of the quality of its wood and the produc-tion of a red pigment and much coveted in colonial times for dyeing fabrics and due to predatory extractivism, it was almost extinct. Currently, wood is much sought after for the manufacture of bows for violins for its ideal stiffness and density. The scarcity of chemical and biological studies of different parts of the plant motivated the chemical composition of the essential oil of the flowers as well as the evaluation of the acaricide, cytotoxicity properties against saline ar-temia and antioxidant. The flowers of C. echinata were collected on the campus of the Federal Rural University of Pernambuco. The essential oil (EO) was extracted from the hydrodistilla-tion technique by a modified Clevenger type apparatus. The chemical composition of the oil was determined by gas chromatography coupled to a mass spectrometer. Residual contact was the method selected to evaluate the acaricide action on Tetranychus urticae and the biological model selected for cytotoxicity evaluation was That of A. salina. The EO of the flowers pre-sented monoterpenes as the main chemical class. The main compounds identified were linalool (32.33%), Z-jasmona (14.94%) and [beta]-E-ocimene (10.44%). The essential oil for the control of T. urticae presented a LC50 = 290.15 uL/mL. The EO revealed an antioxidant capacity for the free radical DPPH˙ estimated at EC50 = 364.10 ug/mL, while for the free radical ABTS˙+ was EC50 = 280.50 ug/mL. The oil exhibited a LC50 = 97.41ug/mL for the toxicity test against A. salina. This study showed that the essential oil of C. echinata flowers has acaricide, antioxidant and cytotoxic biological property against A. salina.
Obtenção de modelos QSAR na plataforma livre de computação em nuvem OCHEM e uma aplicação para atividade acaricida de monoterpenos
(2022-06-08) Silva, Esterfania Laís da; Batista, Hélcio José; http://lattes.cnpq.br/1234630357325796; http://lattes.cnpq.br/0889940460113959
The present work focuses in using the resources of the free access cloud computing web platform OCHEM - English Online Chemical Modeling Environment, designed for data storage, development of models and publication of chemical information. As an example of application on the platform, we sought to obtain QSAR models - Quantita-tive Structure-Activity Relation for insecticidal activity on the species of Spider Mite (Tetranychus Urticae), a common pest in family farming in the Northeast region of Bra-zil, from a series of compounds of the monoterpene class: α-pinene, p-cymene, β-pinene, menthol, α-terpineol, geraniol, R-limonene, 1-8-cineole, R-linalool, terpenyl ac-etate, and terpinolene and 4- (S) ter-pineol. To this end, we carried out a literature review on the monoterpenes usage in agriculture pest control, as well as a review of the Quantitative Structure-Activity Relation-ship method, QSAR. For the application of the OCHEM platform to obtain QSAR models for the series of monoterpenes, we per-formed the molecular modeling of the series compounds by methods of Quantum Chemistry, generating the molecular structures in order to feed the OCHEM platform, to calculate the molecular descriptors and obtain of QSAR models. We explored differ-ent sets of descriptors as well as different types of machine learning methods, such as Multiple Linear Regression (MLR), Partial Least Squares (PLS) and Neural Networks (NN - Neural Networks). The models so obtained for the series under study, however, did not have sufficient statistical quality, probably due, firstly, to the small number of compounds in the training set with available experimental data and, also, to a likely strong degree of non-linearity present in the relationship between the chosen de-scriptors and the activity.