The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led society to live with a serious public health problem. In this sense, repositioning of antiretrovirals has ...captured the attention of the scientific community. Tenofovir disoproxil fumarate (TDF) is an antiretroviral compound that is used to treat acquired immune deficiency syndrome (AIDS) and hepatitis B. In this short report, we present a scale-up investigation of TDF by in situ infrared spectroscopy monitoring and a forced degradation study to describe a new degradation product. Finally, we have evaluated TDF in vitro for SARS-CoV-2 for the first time foreseeing the using of this medicine in pre-clinical and clinical investigations for the COVID-19 (coronavirus disease 2019) treatment.
Sulfonated polystyrene compounds (SPS) were synthesized, leading catalytically active polymeric materials with high sulfonation degree. Catalyst performance was evaluated in beef tallow and soybean ...oil transesterification reactions. The SPS leading to conversion of 85 and 75% for soybean oil and beef tallow in to ethyl esters, respectively, and 94% of the soybean oil methyl esters. Therefore, sulfonated polymeric compounds obtained from linear polystyrene are efficient catalysts.
Sulfonated polystyrene compounds (SPS) were synthesized from linear polystyrene (PS), leading to catalytically active polymeric materials with sulfonation degrees between 5.0 and 6.2
mmol SO
3H/g of dry polymer. Catalyst performance was evaluated in beef tallow and soybean oil transesterification with ethanol and methanol. The SPS were used at 20
mol% of –SO
3H groups in relation to the oil mass. Methanol:oil molar ratios of 3:1, 6:1, 9:1, and 100:1 were employed, and the reactions lasted between 3 and 18
h. The SPS samples were insoluble in the reaction media and led to conversions of 85 and 75% of refined soybean oil and beef tallow with a 53
mg KOH/g acid number, respectively. There was an increase in ester production for reactions carried out at higher methanol:oil molar ratio and, in some cases, products with as much as 94% methyl ester content were obtained. Therefore, sulfonated polymeric compounds obtained from linear polystyrene are efficient catalysts for the alcoholysis of refined vegetable oils and raw materials containing high acid numbers.
This work describes the structural elucidation of the sex pheromone of the soybean stink bug, Pallantia macunaima. The biological activity of the synthetic pheromone was demonstrated by behavioral ...and EAD experiments. Furthermore, the absolute configuration of the natural pheromone was determined as (6R,10S)-6,10,13-trimethyltetradecan-2-one. This is the first ketone identified as a male-produced sex pheromone in Pentatomidae, and the trivial name, pallantione, was assigned to this novel pheromone molecule.
Peptides from skin secretions of amphibians are considered important components of their immune system and also play a relevant role in their defense mechanism against predators. Herein, by using ...mass spectrometry (MS), we characterize the sequence of 13 peptides from the gland secretion of the hylid tree frog, Boana punctata. Using in situ matrix-assisted laser desorption ionization imaging MS of a transverse section of the skin tissue, we show that some peptides are stored as longer molecules that are cleaved after being secreted, whereas others do not undergo any modification. Sequence comparison with peptides from other Boana species and analysis of the three-dimensional theoretical structure indicate that this cleavage depends on both the presence of a specific sequence motif and the secondary structure. The fact that peptides undergo a rapid cleavage upon secretion suggests that stored and secreted peptides may have distinct roles for anuran survival, including defense against pathogens and predators.
A variety of techniques have been employed in order to reduce problems caused by the crystallization of paraffin during the production and/or transportation of paraffin oils and derivatives. ...Methacrylate copolymers are known as additives which reduce the pour point of these oils. This paper describes the synthesis, characterization and performance evaluation of these copolymers, having as an initial step the synthesis of the alkyl methacrylate monomers by transesterification of methyl methacrylate (MMA) with C
14, C
16 and C
18 fatty alcohols. The copolymerization of these monomers with MMA was then performed, with molar ratios of 30:70, 50:50 and 70:30 for alkyl methacrylate:methyl methacrylate. All products were characterized by FTIR,
1H NMR and gel permeation chromatography (GPC). All the methacrylic copolymers lead to a large reduction in the pour point of samples of Brazilian diesel oil. Oil samples containing 50
ppm of the polymeric additive with ca. 70% octadecyl methacrylate units showed a 22
°C reduction in their pour points, thus establishing the large efficiency of the products synthesized in this work.
Phthia picta
is part of a complex of true bugs (Heteroptera) in Brazil that attack tomatoes, being particularly damaging because nymphs and adults feed on both leaves and fruit. Gas chromatography ...(GC) of aeration extracts of adult males vs. females revealed the presence of a male-specific compound. GC-electroantennographic detector experiments indicated that the antennae of females are highly sensitive to this male-specific compound. GC-mass spectrometry and GC-FTIR analyses suggested a methyl branched hydrocarbon structure for this compound. After synthesis of three different proposed structures, the natural product was indentified as 5,9,17-trimethylhenicosane, which was strongly attractive to females in Y-tube olfactometer bioassays. Analysis of dissected body parts of adults revealed that the pheromone is produced in the lateral accessory glands of the metathoracic scent gland of males only.
Thaumastocoris peregrinus is an introduced “true bug” that is now a severe pest in Eucalyptus plantations of various Southern Hemisphere countries. The semiochemicals of thaumastocorids are ...completely unknown. Therefore, volatile chemicals from T. peregrinus nymphs and adults were identified as possible leads for pheromones potentially useful for control. The contents of nymphal exocrine glands, which are shed at molting, were identified from extracts of exuviae. Adults lack functional metathoracic scent glands that are characteristic of most heteropterans; however, both males and females possess a glandular-appearing hold-fast organ that they quickly extrude posteriorly when disturbed. Whole body hexane extracts from males and females were prepared by freezing the insects in a flask so that they extruded the hold-fast organ, and then they were extracted with hexane. Volatiles from nymphal exuviae included benzaldehyde, octanol, (E)-2-octenol, octanoic acid, decanal, and hexanoic acid. Adult volatiles included 3-methylbut-2-en-1-yl butyrate and 3-methylbut-3-en-1-yl butyrate.
In a previous study we reported the identification of the first ketone found in the Pentatomidae family, the sex attractant pheromone of the male stink bug Pallantia macunaima, ...(6R,10S)-6,10,13-trimethyltetradecan-2-one. Here we describe an efficient enantioselective route for the synthesis of the four stereoisomers of this pheromone. The synthesis was conceived as the connection of two chiral building blocks, employing (R)- or (S)-citronellol and methyl (S)-3-hydroxy-2-methylpropionate as the source of chirality.
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Rationale
4,7‐Dichloroquinoline (DCQ) represents a group of synthetic molecules inspired by natural products with important roles in biological and biomedical areas. This work aimed to characterize ...DCQ and its derivatives by high‐resolution electrospray ionization (ESI) mass spectrometry and tandem mass spectrometry (ESI‐MS/MS), supported by theoretical calculations. Biological assays were carried out with DCQ and its derivatives to determine LC50 values against Aedes aegypti larvae.
Methods
Five DCQ derivatives were synthesized by using previously described protocols. ESI‐MS/MS analyses were carried out with a quadrupole/time‐of‐flight and ion‐trap instrument. The proposed gas‐phase protonation sites and fragmentation were supported by density functional theory calculations. The larvicidal tests were performed with the Ae. aegypti Rockefeller strain, and the LC50 values were determined by employing five test concentrations. Larval mortality was determined after treatment for 48 h.
Results
DCQ bromides or aldehydes (C‐3 or C‐8 positions), as well as the trimethylsilyl derivative (C‐3 position), were prepared. Detailed ESI‐MS/MS data revealed heteroatom elimination through an exception to the even‐electron rule, to originate open‐shell species. Computational studies were used to define the protonation sites and fragmentation pathways. High activity of DCQ and its derivatives against Ae. aegypti larvae was demonstrated.
Conclusion
Our results provided a well‐founded characterization of the fragmentation reactions of DCQ and its derivatives, which can be useful for complementary studies of the development of a larvicidal product against Ae. aegypti.
Carbenoids are a class of highly reactive reagents that play an important role in modern organic synthesis. These species are very similar to singlet state carbenes since they have an ambiphilic ...character and react by a concerted mechanism allowing stereospecific transformations. Herein, we discuss these and other chemical aspects of zinc, lithium and magnesium carbenoids as well as relevant applications of these intermediates in organic synthesis.
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