Efeito do 1-Metilciclopropeno no amadurecimento de quivi.

O quivi é um fruto extremamente sensível ao etileno. Pequenas concentrações desse fitohormônio causam amadurecimento e amolecimento precoces nesse fruto. O 1-MCP, um inibidor da ação do etileno, vem sendo utilizado para retardar o processo de amadurecimento em diferentes frutos. Esse inibidor bloqueia temporariamente o acesso do etileno aos receptores, inibindo sua ação nos tecidos vegetais. A resposta ao tratamento com 1-MCP depende da dose, espécie, cultivar e do estádio de desenvolvimento em que o produto é aplicado. Diferentes estudos têm sido realizados visando elucidar a ação do 1-MCP em quivis, entretanto, a maioria dos estudos relata o efeito desse inibidor em quivis após o armazenamento em atmosfera refrigerada e controlada, não elucidando o papel do 1-MCP em temperatura ambiente, além disso, os autores não relatam o efeito do gás sobre a qualidade sensorial de quivis. Nesse sentido, este trabalho teve por objetivo avaliar o efeito do 1-MCP durante a evolução da maturação de quivis em temperatura ambiente. Nesse estudo foram utilizadas duas cultivares de quivi, Monty, a qual é mais bem estudada durante o período pós-colheita, e Tewi, que apresenta poucas informações do manejo pós-colheita. Frutos de ambas as cultivares, tratados e não tratados com 1-MCP após a colheita foram mantidos em temperatura ambiente durante 15 dias. A evolução da maturação foi monitorada a cada três dias através da medida da firmeza de polpa, teor de sólidos solúveis, acidez total titulável e avaliação da qualidade sensorial. Conforme esperado, a firmeza de polpa foi menor nos frutos não tratados com 1-MCP e maior nos frutos que receberam o tratamento em ambas cultivares estudadas e em todos os períodos avaliados. O teor de SS e de ácido cítrico foi influenciado significativamente pela aplicação de 1-MCP nos frutos de ambas as cultivares e em todos os períodos de avaliação, verificando-se maior teor de SS e menor de ácido cítrico em frutos não tratados. O 1-MCP foi eficiente no atraso do processo de amadurecimento de quivis das cultivares Monty e Tewi, onde se verificou a manutenção da firmeza de polpa dos frutos. No entanto, frutos que receberam o tratamento apresentaram qualidade sensorial inferior no período analisado

Search for antimicrobial activity among fifty-two natural and synthetic compounds identifies anthraquinone and polyacetylene classes that inhibit Mycobacterium tuberculosis

Drug-resistant tuberculosis threatens to undermine global control programs by limiting treatment options. New antimicrobial drugs are required, derived from new chemical classes. Natural products offer extensive chemical diversity and inspiration for synthetic chemistry. Here, we isolate, synthesize and test a library of 52 natural and synthetic compounds for activity against Mycobacterium tuberculosis. We identify seven compounds as antimycobacterial, including the natural products isobavachalcone and isoneorautenol, and a synthetic chromene. The plant-derived secondary metabolite damnacanthal was the most active compound with the lowest minimum inhibitory concentration of 13.07 μg/mL and a favorable selectivity index value. Three synthetic polyacetylene compounds demonstrated antimycobacterial activity, with the lowest MIC of 17.88 μg/mL. These results suggest new avenues for drug discovery, expanding antimicrobial compound chemistries to novel anthraquinone and polyacetylene scaffolds in the search for new drugs to treat drug-resistant bacterial diseases

Matrix-assisted laser desorption ionization hydrogen/deuterium exchange studies to probe peptide conformational changes

AbstractHydrogen/deuterium (H/D) exchange chemistry monitored by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry is used to study solution phase conformational changes of bradykinin, α-melanocyte stimulating hormone, and melittin as water is added to methanol-d4, acetonitrile, and isopropanol-d8 solutions. The results are interpreted in terms of a preference for the peptides to acquire more compact conformations in organic solvents as compared to the random conformations. Our interpretation is supported by circular dichroism spectra of the peptides in the same solvent systems and by previously published structural data for the peptides. These results demonstrate the utility of MALDI-TOF as a method to monitor the H/D exchange chemistry of peptides and investigations of solution-phase conformations of biomolecules

Messages that increase women’s intentions to abstain from alcohol during pregnancy: results from quantitative testing of advertising concepts

Background: Public awareness-raising campaigns targeting alcohol use during pregnancy are an important part of preventing prenatal alcohol exposure and Fetal Alcohol Spectrum Disorder. Despite this, there is little evidence on what specific elements contribute to campaign message effectiveness. This research evaluated three different advertising concepts addressing alcohol and pregnancy: a threat appeal, a positive appeal promoting a self-efficacy message, and a concept that combined the two appeals. The primary aim was to determine the effectiveness of these concepts in increasing women’s intentions to abstain from alcohol during pregnancy.Methods: Women of childbearing age and pregnant women residing in Perth, Western Australia participated in a computer-based questionnaire where they viewed either a control or one of the three experimental concepts. Following exposure, participants’ intentions to abstain from and reduce alcohol intake during pregnancy were measured. Other measures assessed included perceived main message, message diagnostics, and potential to promote defensive responses or unintended consequences.Results: The concepts containing a threat appeal were significantly more effective at increasing women’s intentions to abstain from alcohol during pregnancy than the self-efficacy message and the control. The concept that combined threat and self-efficacy is recommended for development as part of a mass-media campaign as it has good persuasive potential, provides a balance of positive and negative emotional responses, and is unlikely to result in defensive or unintended consequences.Conclusions: This study provides important insights into the components that enhance the persuasiveness and effectiveness of messages aimed at preventing prenatal alcohol exposure. The recommended concept has good potential for use in a future campaign aimed at promoting women’s intentions to abstain from alcohol during pregnanc