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Controlled release formulations of Ruta essential oil obtained by ionic gelation were developed. The presence of rue essential oil in the alginate and chitosan capsules was evidenced by Fourier transform infrared spectroscopy and differential scanning calorimetry. Release studies revealed that in acidic conditions (pH 4.2), the CHS-REO particles reached a Sw of 240% (w/w) in 30 days and 101% (w/w) for ALG-REO particles, generating a RR of 23.7% for CHS-REO and 20.4% for ALG-REO. On the other hand, at pH 6.8 it favored the Sw for ALG-REO 840% (w/w) and therefore the RR (45.6%) and disfavored the Sw of CHS-REO generating low RR (16.9%). Encapsulated rue essential oil showed equal or superior nematicidal activity against the nematode Melodogyne ssp., compared to free oil and a synthetic nematicide such as Carbofuran, without having a phytotoxic effect on the plant. This study revealed that REO encapsulated in biopolymeric matrices can be used as new nematicide formulations.

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As a result of more restrictive legislation regarding the use of pesticides, over the last two decades, the demand for new soil fumigants has increased. These compounds can come from a variety of sources, including organic residues. In this study, we identified in the cassava wastewater volatiloma a molecule with potential to be developed as a new fumigant nematicide. Cassava wastewater (20 mL) releases volatile compounds toxic to Meloidogyne javanica second-stage juveniles (J2), causing J2 mortality up to 89%. Through gas chromatography-mass spectrometry, eight compounds were identified in the cassava wastewater volatiloma, with alcohols being the major class. The compounds ethyl butanoate and butyric acid identified in cassava wastewater volatiloma were selected for in vitro nematicidal activities and substrate fumigation tests. The lethal concentration predicted LC50-48 hr values (effective doses to kill 50% of M. javanica J2 population after 48 h of exposure) were 172.6 µg ∙ mL - 1 and 301.2 µg ∙ mL - 1 for butyric acid and ethyl butanoate, respectively. In a pot assay, the application of butyric acid and ethyl butanoate as a soil fumigant, at a dose of 0.5 mL ∙ kg - 1 substrate, significantly (P < 0.05) decreased M. javanica infectivity and reproduction compared to the negative control (water). However, ethyl butanoate proved to be a more efficient soil fumigant (P < 0.05) than butyric acid, as its application reduced the number of galls and eggs to the level of the commercial fumigant Dazomet. This study is the first to demonstrate the potential of ethyl butanoate as a soil fumigant against M. javanica.

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BACKGROUND: While searching for novel small molecules for new organic pesticide agents against plant-parasitic nematodes, we found that the hexane extract from the roots of Senecio sinuatos and its main secondary metabolite, 3ß-angeloyloxy-6ß-hydroxyfuranoeremophil-1(10)-ene (1), possess nematicidal activity against the second stage juvenile (J2) of Meloidogyne incognita and Nacobbus aberrans. Both species reduce yield of various vegetable crops. These results encouraged us to synthesize esters 3-9 formed by diol 2, obtained by alkaline hydrolysis of 1 and acetic anhydride, benzoic acid, 2-nitrobenzoic acid, 2-bromobenzoic acid, 4-nitrobenzoic acid, 4-bromobenzoic acid, and 4-methoxybenzoic acid, respectively. The nematicidal activity of these esters was evaluated and compared with that of the free benzoic acids. RESULTS: Natural product 1 and derivatives 2-9 were obtained and characterized by their physical and spectroscopic properties, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) experiments; X-ray diffraction analysis established their absolute configuration. The nematicidal activity of compounds 1-9 was assessed in vitro against M. incognita and N. aberrans J2 and was compared to activity shown by benzoic acid, 2-nitrobenzoic acid, 2-bromobenzoic acid, 4-nitrobenzoic acid, 4-bromobenzoic acid, and 4-methoxybenzoic acid. The esters suppressed nematodes more than free benzoic acid. Nacobbus aberrans J2 were suppressed, with compounds 5, 6, and 8 being the most active. CONCLUSION: Esters formed by 3ß,6ß-dihydroxyfuranoeremophil-1(10)-ene and ortho- or para-substituted benzoic acids containing electron acceptor groups had nematicidal activity against N. aberrans. These compound can potentially serve as a model for the development of new organic nematicidal agents. © 2022 Society of Chemical Industry.

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Nacobbus aberrans ranks among the "top ten" plant-parasitic nematodes of phytosanitary importance. It causes significant losses in commercial interest crops in America and is a potential risk in the European Union. The nematicidal and phytotoxic activities of seven plant extracts against N. aberrans and Solanum lycopersicum were evaluated in vitro, respectively. The chemical nature of three nematicidal extracts (EC50,48h ≤ 113 µg mL-1) was studied through NMR analysis. Plant extracts showed nematicidal activity on second-stage juveniles (J2): (≥87%) at 1000 µg mL-1 after 72 h, and their EC50 values were 71.4-468.1 and 31.5-299.8 µg mL-1 after 24 and 48 h, respectively. Extracts with the best nematicidal potential (EC50,48h < 113 µg mL-1) were those from Adenophyllum aurantium, Alloispermum integrifolium, and Tournefortia densiflora, which inhibited L. esculentum seed growth by 100% at 20 µg mL-1. Stigmasterol (1), ß-sitosterol (2), and α-terthienyl (3) were identified from A. aurantium, while 1, 2, lutein (4), centaurin (5), patuletin-7-ß-O-glucoside (6), pendulin (7), and penduletin (8) were identified from A. integrifolium. From T. densiflora extract, allantoin (9), 9-O-angeloyl-retronecine (10), and its N-oxide (11) were identified. The present research is the first to report the effect of T. densiflora, A. integrifolium, and A. aurantium against N. aberrans and chemically characterized nematicidal extracts that may provide alternative sources of botanical nematicides.

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Culture medium composition is one of the most important parameters to analyze in biotechnological processes with industrial purposes. The aim of this study was to design of a culture medium for optimal growth of the bacterium Pseudoxanthomonas indica H32 allowing its production as biopesticide and biofertilizer. The influence of several carbon and nitrogen sources and their molar ratios on P. indica H32 growth was investigated. The effect of different micronutrients such as mineral salts and vitamin on P. indica H32 growth was determined as well. A mixture design based on Design-Expert 10.0 Software was performed to optimize the culture medium concentration. Finally, in the designed medium, an attribute of the biological mechanism of action of the P. indica H32 against nematodes, was evaluated: the hydrogen sulfide production. It was found that tested carbon/nitrogen ratios were not a significant influence on P. indica H32 growth. Growth of P. indica H32 was favored with use of sucrose, yeast extract and phosphate buffer without the addition of any tested micronutrients. An optimal concentration of 10 g/L sucrose and 5 g/L yeast extract were obtained at a cost of 0.10 $/L. In this concentration, the specific growth rate (µ) and maximal optical density (Xmax) were equal to 0.439 h- 1 and 8.00 respectively. It was evidenced that under the culture conditions used, P. indica H32 produced hydrogen sulfide. The designed medium led to a 1.08 $/L reduction of costs in comparison to LB medium. These results were critical to carry on with biotechnological development of P. indica H32 as a bioproduct.

RESUMO

BACKGROUND: Nacobbus aberrans (Tylenchida: Pratylenchidae) is one of the main plant-parasitic nematodes species that affects crops in Mexico, generating substantial economic losses. Traditionally, the control of the nematodes is carried out using chemical products; however, research efforts are presently focused on the search for new methods for the control of this pest. Natural products derived from plants are an alternative for the control of populations of plant-parasitic nematodes. The genus Heterotheca (Asteraceae) is characterized by containing sesquiterpenes with cadinane skeleton, and some species of this genus exert nematicidal activity. RESULTS: We determined the effects of selected Heterotheca inuloides plant metabolites and some semisynthetic derivatives on the hatching of eggs isolated from the gelatinous matrix and infective second-stage juveniles (J2) of the false root-knot nematode N. aberrans using an in vitro experimental model. Among the evaluated compounds, nematodes were more susceptible to hydroxylated and quinone compounds, whereas the remaining compounds showed moderate or no activity. The presence of the hydroxyl group is essential for nematicidal potential, with changes at the hydroxyl group modifying the nematicidal activity. CONCLUSION: Flowers of Heterotheca inuloides contain bioactive compounds that showed nematicidal activity against N. aberrans. Here we report the nematicidal activities of cadinenes isolated from the flowers of H. inuloides and their semisynthetic derivatives against the false root-knot nematode N. aberrans. © 2018 Society of Chemical Industry.

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The genus Tagetes constitutes a group of antagonistic plant species that are cytotoxic against plant pathogenic nematodes, with T. patula being particularly efficient. The aim of this study was to evaluate the in vitro effect of extracts and semi-purified fractions of T. patula flowers on eggs and second-stage juveniles (J2) of Meloidogyne incognita, M. javanica, and M. paranaensis, as well as to verify the nematicidal effect of the flavonoids present in T. patula flowers. Extracts and semi-purified fractions were obtained from dried T. patula flowers after maceration and liquidification, yielding crude aqueous (CAE) and crude ethanol-water (CEWE) extracts. Dried flowers were also treated with n-hexane to obtain a crude defatted aqueous extract (CDAE) and a crude ethanol-water defatted extract (CEWDE). Then, the CEWE was fractionated, and the ethyl acetate (EAF), ethanol (EF), methanol (MF), and ethanol:water (EWF) fractions were obtained. CAE, CEWE, CDAE, and CEWDE were tested to evaluate their effects on hatching, mobility, and mortality of J2 of M. incognita, M. javanica, and M. paranaensis. EAF, EF, MF, and EWF fractions were tested on the same variables of M. incognita. All extracts significantly reduced J2 hatching of M. incognita, M. javanica, and M. paranaensis when compared to water and water + DMSO. CEWE had nematicidal effects on the three evaluated species, whereas CEWDE demonstrated nematicidal effects against M. incognita and M. javanica, and nematostatic effects on M. paranaensis. This toxic effect showed by CEWE may be related to the high content of quercetin, a major substance present in this sample. It was also observed that EAF accentuated the nematicidal response on Meloidogyne spp., suggesting that other medium polarity (methoxylated) flavonoids act as nematotoxic substances. Thus, these results suggest that quercetin contributes significantly to the nematicidal activity of CEWE and EAF.

Entre as espécies de plantas antagonistas, as do gênero Tagetes apresentam citotoxicidade contra fitonematoides, sendo que T. patula mostra-se eficiente. Assim, objetivou-se avaliar o efeito in vitro de extratos e frações semipurificadas de flores de T. patula sobre ovos e juvenis de segundo estádio (J2) de Meloidogyne incognita, M. javanica e M. paranaensis, e a capacidade nematicida dos flavonoides presentes nas flores de T. patula. Os extratos e frações semipurificadas foram preparados a partir de flores secas de T. patula, que após maceração foram submetidas à turbólise, obtendo-se os extratos bruto aquoso (EBA) e bruto etanol-água (EBEA). Também houve tratamento de flores secas com n-hexano para a obtenção do extrato bruto aquoso desengordurado (EBAD) e do extrato bruto etanol-água desengordurado (EBEAD). Em seguida, o EBEA foi fracionado, sendo obtidas as frações acetato de etila (FAE), etanólica (FE), metanólica (FM) e etanol:água (FEA). O efeito dos extratos EBA, EBEA, EBAD e EBEAD foram avaliados sobre a eclosão, mobilidade e mortalidade de J2 de M. incognita, M. javanica e M. paranaensis. As frações FAE, FE, FM e FEA foram avaliadas frente a M. incognita usando as mesmas variáveis. Os extratos reduziram significativamente a taxa de eclosão de J2 de M. incognita, M. javanica e M. paranaensis, quando comparados com água e água + DMSO. Quanto ao efeito dos extratos, observou-se que EBEA apresentou efeito nematicida para as três espécies avaliadas, e EBEAD demonstrou capacidade nematicida contra M. incognita e M. javanica, e sendo nematostático para M. paranaensis. Tal capacidade pode estar relacionada com o alto teor de quercetina (substância majoritária no EBEA). Observou-se, também, que o fracionamento químico e a obtenção da FAE acentuaram a resposta nematicida sobre Meloidogyne spp., sugerindo que outros flavonoides de média polaridade (metoxilados) atuam como substâncias nematotóxicas.

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RESUMO

The genus Tagetes constitutes a group of antagonistic plant species that are cytotoxic against plant pathogenic nematodes, with T. patula being particularly efficient. The aim of this study was to evaluate the in vitro effect of extracts and semi-purified fractions of T. patula flowers on eggs and second-stage juveniles (J2) of Meloidogyne incognita, M. javanica, and M. paranaensis, as well as to verify the nematicidal effect of the flavonoids present in T. patula flowers. Extracts and semi-purified fractions were obtained from dried T. patula flowers after maceration and liquidification, yielding crude aqueous (CAE) and crude ethanol-water (CEWE) extracts. Dried flowers were also treated with n-hexane to obtain a crude defatted aqueous extract (CDAE) and a crude ethanol-water defatted extract (CEWDE). Then, the CEWE was fractionated, and the ethyl acetate (EAF), ethanol (EF), methanol (MF), and ethanol:water (EWF) fractions were obtained. CAE, CEWE, CDAE, and CEWDE were tested to evaluate their effects on hatching, mobility, and mortality of J2 of M. incognita, M. javanica, and M. paranaensis. EAF, EF, MF, and EWF fractions were tested on the same variables of M. incognita. All extracts significantly reduced J2 hatching of M. incognita, M. javanica, and M. paranaensis when compared to water and water + DMSO. CEWE had nematicidal effects on the three evaluated species, whereas CEWDE demonstrated nematicidal effects against M. incognita and M. javanica, and nematostatic effects on M. paranaensis. This toxic effect showed by CEWE may be related to the high content of quercetin, a major substance present in this sample. It was also observed that EAF accentuated the nematicidal response on Meloidogyne spp., suggesting that other medium polarity (methoxylated) flavonoids act as nematotoxic substances. Thus, these results suggest that quercetin contributes significantly to the nematicidal activity of CEWE and EAF.(AU)

Entre as espécies de plantas antagonistas, as do gênero Tagetes apresentam citotoxicidade contra fitonematoides, sendo que T. patula mostra-se eficiente. Assim, objetivou-se avaliar o efeito in vitro de extratos e frações semipurificadas de flores de T. patula sobre ovos e juvenis de segundo estádio (J2) de Meloidogyne incognita, M. javanica e M. paranaensis, e a capacidade nematicida dos flavonoides presentes nas flores de T. patula. Os extratos e frações semipurificadas foram preparados a partir de flores secas de T. patula, que após maceração foram submetidas à turbólise, obtendo-se os extratos bruto aquoso (EBA) e bruto etanol-água (EBEA). Também houve tratamento de flores secas com n-hexano para a obtenção do extrato bruto aquoso desengordurado (EBAD) e do extrato bruto etanol-água desengordurado (EBEAD). Em seguida, o EBEA foi fracionado, sendo obtidas as frações acetato de etila (FAE), etanólica (FE), metanólica (FM) e etanol:água (FEA). O efeito dos extratos EBA, EBEA, EBAD e EBEAD foram avaliados sobre a eclosão, mobilidade e mortalidade de J2 de M. incognita, M. javanica e M. paranaensis. As frações FAE, FE, FM e FEA foram avaliadas frente a M. incognita usando as mesmas variáveis. Os extratos reduziram significativamente a taxa de eclosão de J2 de M. incognita, M. javanica e M. paranaensis, quando comparados com água e água + DMSO. Quanto ao efeito dos extratos, observou-se que EBEA apresentou efeito nematicida para as três espécies avaliadas, e EBEAD demonstrou capacidade nematicida contra M. incognita e M. javanica, e sendo nematostático para M. paranaensis. Tal capacidade pode estar relacionada com o alto teor de quercetina (substância majoritária no EBEA). Observou-se, também, que o fracionamento químico e a obtenção da FAE acentuaram a resposta nematicida sobre Meloidogyne spp., sugerindo que outros flavonoides de média polaridade (metoxilados) atuam como substâncias nematotóxicas.(AU)

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The chemical composition of the essential oils from aerial parts of Pectis apodocephala and Pectis oligocephala were analyzed by GC-MS. The essential oils of these species were predominantly constituted by monoterpenes. Geranial (42.9-44.5 percent), neral (32.2-34.2 percent) and alpha-pinene (10.7-11.4 percent) were the main constituents in the oil of P. apodocephala, while p-cymene (50.3-70.9 percent) and thymol (24.4-44.7 percent), were the prevalent compounds in the oil of P. oligocephala. The essential oils were tested against the root knot nematode Meloidogyne incognita and Aedes aegypti larvae survival. The results obtained show that both essential oils exhibited significant activity and could be considered as potent natural namaticidal and larvicidal agents.

A composição química dos óleos essenciais das partes aéreas de Pectis apodocephala e Pectis oligocephala foi analisada por CG-EM. Os óleos essenciais destas espécies foram predominantemente constituídos por monoterpenos. Geranial (42, 9-44, 5 por cento), neral (32, 2-34, 2 por cento) e alfa-pineno (10, 7-11, 4 por cento) foram os constituintes majoritários no óleo de P. apodocephala, enquanto p-cimeno (50, 3-70, 9 por cento) e timol (24, 4-44, 7 por cento), foram os compostos prevalentes no óleo de P. oligocephala. Ambos os óleos foram testados contra o nematóide Meloidogyne incognita e larvas do mosquito Aedes aegypti no terceiro estágio. Os resultados obtidos mostraram que os óleos exibem significante atividade e podem, portanto, ser considerados como potenciais agentes nematicida e larvicida naturais.

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