Foram isoladas e identificadas duas neolignanas: a surinamensina e a virolina. A tendência geral observada nos resultados foi de aumento da intensidade dos efeitos alelopáticos inibitórios em função do aumento da concentração, com inibições máximas obtidas, sempre, na concentração de 8,0 mg L -1 . A surinamensina apresentou maior potencial para inibir a germinação e o desenvolvimento da radícula e do hipocótilo do que a virolina, independentemente da espécie receptora e do fator da planta analisado. Considerando-se as intensidades dos efeitos promovidos sobre os três fatores das plantas, o desenvolvimento da radícula e o do hipocótilo foram mais intensamente inibidos pelas duas substâncias do que a germinação das sementes. À exceção dos efeitos verificados sobre o desenvolvimento do hipocótilo, malícia foi a espécie de maior sensibilidade aos efeitos alelopáticos das duas neolignanas, enquanto mata-pasto foi aquela que evidenciou inibições de menor magnitude.Palavras-chave: alelopatia, inibição, planta daninha, surinamensina, virolina. ABSTRACT -The objective of this research was to isolate, identify and characterize the allelopathic activity of chemical compounds in Virola surinamensis leaves. The process of isolation and identification of chemicals compounds involved the use of organic solvents and Magnetic Nuclear
This study investigates the influence of the flood pulse on the reproductive biology of the auchenipterids Tocantisia piresi (Miranda Ribeiro, 1920) and Auchenipterus nuchalis (Spix & Agassiz, 1829) from the middle Xingu River in the Brazilian state of Pará. The specimens were collected every three months between April, 2012, and January, 2014, covering four distinct periods (flood, ebb, dry, and filling). The sex ratio, size at first maturity, gonadosomatic index, and condition factor were analysed in the two species, and evaluated in the context of the different hydrological periods. A total of 897 specimens of T. piresi were collected, of which 467 were female, and 430 males, and 383 A. nuchalis (286 females and 97 males). In T. piresi, the sex ratio was biased only in the filling and ebb periods, whereas in A. nuchalis, it departed significantly from the expected ratio of 1:1 in all periods, with a predominance of females. The female T. piresi mature at a smaller size than the males, with the opposite of the pattern being recorded in A. nuchalis. In T. piresi, the breeding peak was observed during the low water periods, whereas in A. nuchalis, the peak was recorded in the flood periods. Male and female T. piresi presented similar positively allometric growth rates, whereas in A. nuchalis, growth was negatively allometric, but rates were different between genders. A higher condition factor was recorded in the females of both species during the ebb period. Overall, the results of this study reveals distinct flood pulse effects on the reproductive parameters of the two auchenipterid species studied; for A. nuchalis the spawning seems to happen at the flood period and for T. piresi at the dry season of the middle Xingu River.Keywords: Amazon, Auchenipteridae, flood pulse, fish reproduction. Influência do pulso de inundação na reprodução de
Um novo derivado de antraquinona, denominado guepinone (1), juntamente com as conhecidas substâncias isossulocrina (2) e cloroissosulocrina (3) foram isolados de uma cultura em arroz de Pestalotiopsis guepinii, um fungo endofitico de Virola michelii. Os compostos foram identificados pela análise de seus dados espectrométricos de RMN 1D e 2D e EM. A atividade antimicrobiana dos compostos isolados foi avaliada e a cloroisossulcrina (3) foi a mais ativa.A new anthraquinone derivative, named guepinone (1), along with the known substances isosulochrin (2) and chloroisosulochrin (3), were isolated from a rice culture of Pestalotiopsis guepinii, an endophytic fungus of Virola michelii. The compounds were identified by analysis of 1D and 2D NMR and MS spectral data. The antimicrobial activity of these compounds was evaluated and chloroisosulchrin (3) was the most active. Keywords: Virola michelii, Pestalotiopsis guepinii, anthraquinone derivatives, endophytic fungus IntroductionEndophytic fungi have been collected from nearly all plants studied. They colonize the plants without causing visible disease symptoms. The function of the host plant is not yet clear and is supposed to depend on the organ-fungus interaction of each plant indicating that there are no neutral interactions but a balanced antagonism between the plant and the endophytic fungi. Endophytic fungi are very useful in agriculture and industry. They can be used as a tool for introduction of genes of interest into the plants, 2,3 like plague and pathogen inhibitors. 4,5 They are also a source of primary and secondary metabolites of interest.In spite of the several reports concerning the production of substances by endophytic fungi that show biological activities, such as fungicide, herbicide and algicide, among others, 6 there are not many studies concerning the chemical composition of endophytic microorganisms, especially when we analize the wide fungic biodiversity and the specificity in the colonization of plants by fungi. This paper deals with the study of the metabolites produced by the fungus Pestalotiopsis guepinii isolated from Virola michelii.V. michelii belongs to the family Myristicaceae and it is used in folk medicine in the treatement of diseases caused by fungi and in the treatment of infections of the skin.7 Phytochemical study, anti-inflammatory and allelopathic activities of the leaves of the V. michelii were reported. [8][9][10][11] There have been described 205 species of Pestalotiopsis, 12 some of these produce secondary metabolites with important activities, like phytotoxic, antifungic, antioxidant and anticancer activities.13 Studies with P. guepinii lead Novel Anthraquinone Derivatives Produced by Pestalotiopsis guepinii J. Braz. Chem. Soc. 994 to the isolation of the diterpenoid taxol, an important anticancer drug.14 Pestalotiopsis also produce sesquiterpenes, other diterpenes, phenolic derivatives and anthraquinone derivatives. [14][15][16] This paper reports the isolation and structural elucidation of three anthraquinone derivat...
. RESUMO -Muitas substâncias químicas disponíveis na natureza, produzidas por plantas ou por microrganismos, podem oferecer novas e excelentes oportunidades para diversificar o controle de pragas na agricultura e na prática agrícola, e, nesse sentido, os fungos podem contribuir de forma positiva. O objetivo deste trabalho foi caracterizar o potencial inibitório na germinação de sementes e no desenvolvimento de plântulas de duas espécies de plantas daninhas em relação aos extratos e substâncias químicas obtidas da biomassa produzida por Pestalotiopsis guepinii -um fungo endofítico da espécie Virola michelii. Foram desenvolvidos bioensaios em condições controladas de 25o C e fotoperíodo de 12 horas, para germinação, e de 25o C e fotoperíodo de 24 horas, para desenvolvimento da radícula e do hipocótilo. Os extratos brutos foram analisados em concentração de 1,0% (m/v). Os resultados indicaram os extratos mais polares (MeOH) como de maior potencial inibitório, porém os efeitos promovidos pelos extratos hexânicos e acetato de etila foram expressivos, especialmente em relação à germinação das sementes. Comparativamente, a germinação das sementes das espécies de plantas daninhas se mostrou mais sensível aos efeitos do que o desenvolvimento das plântulas. Das espécies receptoras, Mimosa pudica (malícia) apresentou maior sensibilidade aos efeitos inibitórios dos extratos. Entretanto, na germinação de sementes da espécie Senna obtusifolia (mata-pasto), o extrato MeOH-1 apresentou 100% de inibição. As substâncias ergosterol e peróxido de ergosterol, isoladas do extrato hexânico, quando testadas isoladamente, apresentaram potencial inibitório sempre abaixo dos 35%, não repetindo o potencial inibitório do extrato hexânico, de onde foram isoladas. Quando testadas juntas, não se verificaram aumentos expressivos na atividade herbicida, embora acréscimos na atividade inibitória tenham sido observados.Palavras-chave: germinação, hipocótilo, inibição, radícula, sementes, Virola michelii, Mimosa pudica, Senna obtusifolia.ABSTRACT -Many of the chemical compounds found in nature that are produced by plants or microorganisms can offer new and efficient ways of controlling pests in agriculture and agricultural practice, with the help of fungi. The objective of this work is to characterize the inhibitory potential for seed germination and the plantlet development of two weed species using extracts and compounds obtained from biomass produced by Pestalotiopsis guepinii, an endophytic fungus of the species Virola michelii. The bioassays were developed under controlled conditions at 25 °C and 12-hour photoperiod for germination, and at 25 °C and 12-hour photoperiod for root and hypocotyl development. The crude extracts were analyzed at a concentration of 1.0% (m/v). The results showed that the more polar extracts (MeOH -1 and MeOH -2 ) have the highest inhibitory potential, although the hexane and ethyl acetate extract effects were important, especially for seed germination. Comparatively, weed seed germination was more sensitive to the ef...
Cancer is one of the most deadly diseases in the world, being related to the disordered growth of defective cells which produces harmful substances to the body. In this context, one of the great challenges of science is finding an effective bioactive compound for treating of this disease and microorganisms from restrictive environments, such as caves, are indicated as a promising source of these compounds. The objective of this work was to evaluate the extracts cytotoxic effects obtained from cultures of two bacterial strains isolated from Pedra da Cachoeira cave, Altamira-PA, located in a preserved forest fragment in the Eastern Amazon. Bacteria were identified by DNA sequencing analysis encoding ribosomal RNA. The choice of the ideal period of microbial development, aiming at the biocompounds production, was based in a kinetic study realized from a growth curve. Organic extracts were produced after 30 hours (stationary phase) and 40 hours (decline phase) of cultivation, obtaining four extracts by liquid -liquid partition of culture medium and four extracts from the bacterial cells. In vitro cytotoxicity tests were performed with B16F10 tumor cells using the MTT method. From the phylogenetic analyzes of the DNA sequences of both strains, a cluster with the species Bacillus subtilis was verified. The extracts obtained were subjected to cytotoxic assays and their cell viability was evaluated based on the minimum inhibitory concentration (IC50) and selectivity index (IS), with the CV26AI30H extract having an IC50 value of 83.99 and IS greater than 4.70.
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