The action of clove (Syzygium aromaticum ) and thyme ( Thymus vulgaris) essential oils in the control of Acanthhoscelides obtectus (Coleoptera: Chrysomelidae) in laboratory

The objective of this study was to assess the efficiency of essential oils of cloves (Syzygium aromaticum) and thyme (Thymus vulgaris) on the control of Acanthoscelides obtectus in laboratory conditions. The extraction of the oils was executed by the hydro-distillation method in a Clevenger device, for 4 hours and the design used was completely randomized, with five replications, in a 10x8 factorial arrangement (dozes and exposition time) with ten concentrations (20; 10; 5; 2.5; 1.75; 0.75; 0.5; 0.25 and 0.0% and Tween® 5.0%). Each replication was comprised by 10 unsexed insects of A. obtectus. The variables evaluated are as follows: control efficiency and CL50 through the Proc Probit analysis. The evaluations were carried out in 1, 2, 3, 12, 24, 48, 72, and 96 hours after the treatment. The results demonstrate that the essential oils of cloves and thyme caused 100% of mortality after 48 and 72 hours, respectively, in the 20% concentration. The Cl50 was estimated at 30.46 µL mL-1 for the oil of cloves and 24.93 µL mL-1 for the oil of thyme. The use of essential oils of cloves and thyme represent a viable alternative for use in storehouses for the integrated management of A. obtectus.

A novel biodegradable film based on κ-carrageenan activated with olive leaves extract

This research focused on the development of carrageenan based biodegradable films incorporated with olive leaves extract (OLE). OLE microbial inhibition and its total phenolics (TP) were evaluated. Carrageenan films were produced by casting technique and were characterized by thickness, water vapor permeability (WVP), color, mechanical properties, and infrared spectroscopy. In order to apply as lamb meat packaging, the antimicrobial effect of the films was investigated. Results showed that OLE inhibited E. coli growth and presented excellent TP (41.40 mgGAE/g). Thicknesses of the film with OLE (CAR-OLE) were approximately 28% higher than film without OLE. Addition of OLE reduced the WVP by approximately 54%. CAR-OLE was less resistant to breakage and more flexible showing darker color. FTIR showed interaction of carrageenan with OLE. Results revealed that CAR-OLE promoted 167-fold reduction in initial count of aerobic mesophiles indicating shelf-life extension of lamb meat and promising use as antimicrobial food packaging.

Relationship between Hammett's parameters and in silico density functional with tandem mass ESI-CID fragmentation: Dihydropyridines as prototypes

Over the years, with the instrumental analysis evolution, the relationships between the carried-out results with the data of theoretical analysis in silico and the Hammett's parameters have been reported. They have been very useful for chemical characterization of small organic molecules. Thus, this work aims at showing the feasibility and limitations for Hammett's and density functional theory applications in electrospray ionization-collision-induced dissociation (ESI-CID) fragmentation provision. For this, 13 dihydropyrimidinones para, meta, and orto monosubstituted were studied using ESI and CID in positive mode. As a result, it was observed that the main fragmentation includes the isocyanate and ethanol loses at low energy. Nevertheless, at higher energies, radical ions formed by McLafferty rearrangement were observed. The Hammett plots were correlated fragmentation profiles, showing good linearity for the [M + H]⁺ , which does not occur to radical ions and carbocation's. These tendencies had demonstrated that the stability of protonate and activation energy of secondary ions changes with the pKa. The density functional theory studies indicated that, both nitrogen atoms in the dihydropyrimidinone's prototypes are capable of being protonated. However, the activation energy of fragmentation products is not changed. Therefore, this work has shown information, which can be useful to understand tandem mass spectrometry in ESI-CID conditions for small organic molecules series. This is the first step for normalization of fragmentation pathway.

Sonochemistry: a good, fast and clean method to promote the synthesis of 5-arylidene-2,4-thiazolidinediones

The efficient synthesis of sixteen 5-arylidene-2,4-thiazolidinediones by aldol condensation reaction of 2,4-thiazolidinedione, mono- and di-substituted arenealdehydes and KOH using ultrasound irradiation is reported. The desired compounds were obtained in a few min (10-30 min) with moderate to good yields (25-81%).

Antioxidant properties and UV absorbance pattern of mycosporine-like amino acids analogs synthesized in an environmentally friendly manner

In current study, we report efficient and clean procedure for preparing mycosporine-like amino acids (MMAs) analogs and evaluate their ultraviolet absorbance properties and antioxidant activities. The ultraviolet radiation absorbance patterns of the compounds were recorded and then used to define their molar absorptivities. The antioxidant activities were assessed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and superoxide radical scavenging assays. Eight of nine compounds showed good activity against superoxide radicals, as only one of the analogs exhibited a measurable IC50 in the DPPH assay.

Synthesis, antifungal and cytotoxic activities of 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidinones

A series of sixteen novel thiazolidinone derivatives were synthesized from the efficient one-pot reaction of 2-(piperidin-1-yl)ethylamine, arenealdehydes and mercaptoacetic acid in good yields. Identification and characterization of products were achieved by NMR and GC-MS techniques. The in vitro antifungal activities of all synthesized compounds were evaluated against seven fungi: Candida albicans, Candida parapsilosis, Candida guilliermondii, Cryptococcus laurentii, Geotrichum sp, Trichosporon asahii and Rhodotorula sp. The results are expressed as the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) and the best results were found against the Rhodotorula sp yeast. Two thiazolidinones (4h and 4l), MIC and MFC (16.5 μg/mL) proved to be 1.6 times more active than fluconazole and four of them (4b, 4e, 4g and 4k (MIC and MFC 25 μg/mL)) showed similar activity of standard drug to Rhodotorula sp. In addition, the cytotoxicity of thiazolidinones 4a-p was evaluated on cultured Vero cells and most of them displayed low toxicity (above 98 μg/mL). These preliminary and important results could be considered a starting point for the development of new antifungal agents.

Ultrasound assisted efficient conversion of aromatic aldehydes from oximes

This work describes the ultrasound-assisted regeneration of aldehydes from oximes in ethanol and phosphoric acid as mediator of the reaction. The large scale regeneration of benzaldehyde was shown under similar conditions. The products were isolated in good yields after short reaction times under mild conditions.

Self-etching dental adhesive containing a natural essential oil: anti-biofouling performance and mechanical properties

This study assessed the anti-biofouling performance of an experimental adhesive system containing a naturally occurring essential vegetable oil and examined the following physical and mechanical properties: water sorption (WS) and solubility (SL), microtensile bond strength to dentin (μTBS), and degree of conversion. The following six groups were tested: a self-etching experimental adhesive containing refined essential oil from the seeds of the Butia capitata tree (EAO); an oil-free version of the experimental adhesive (EANO); one group without adhesive as the control (C); and the three following commercial self-etching adhesives: Clearfil Protect Bond (CPB), Clearfil SE Bond, and Adper SE Plus. The antibacterial effect was estimated by microbiological culture on selective/non-selective media, and the results expressed as colony-forming units per unit weight of dry biofilm (CFU mg(-1)). The data were submitted to ANOVA and Tukey's post hoc test (α = 0.05). After 24 h, pH changes were similar in the storage medium of all tested adhesive systems. EAO showed similar levels of antimicrobial activity in a model biofilm microcosm as the commercial self-etching adhesive CPB. Both were effective against total microorganisms, aciduric bacteria, lactobacilli, and Streptococcus mutans. WS and SL were not affected by the presence of the essential oil; the values of EAO were similar to or less than those of commercial equivalents. The incorporation of an essential oil into an experimental adhesive did not influence its monomer conversion result. Immediate μTBS values of EAO and EANO were similar and were greater than those of commercial equivalents. After storage for 6 months, the μTBS of the EAO decreased significantly and became similar to the values of commercial equivalents, while the strength of the EANO was not affected.

Ultrasound-assisted synthesis of aliphatic acid esters at room temperature

This work describes the ultrasound-assisted synthesis of saturated aliphatic esters from synthetic aliphatic acids and either methanol or ethanol. The products were isolated in good yields after short reaction times under mild conditions.

Antioxidant capacity and environmentally friendly synthesis of dihydropyrimidin-(2H)-ones promoted by naturally occurring organic acids

The Biginelli reaction is a multicomponent reaction involving the condensation between an aldehyde, a β-ketoester, and urea or thiourea, in the presence of an acid catalyst, producing dihydropyrimidinones (DHPMs). Owing to their important pharmacological properties, the DHPMs have been studied by many authors. However, most of the methodologies used for the synthesis of these compounds require drastic reaction conditions. In the current study, we report an efficient and clean procedure for preparing DHPMs by the use of citric acid or tartaric acid as a promoter of the Biginelli synthesis in ethanol as solvent. In addition, we have evaluated the antioxidant capacity of the compounds synthesized by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and the thiobarbituric acid-reactive species test. Two compounds presented antioxidant activity and also reduced lipid peroxidation at concentrations of 200 and 300 µM. In summary, we report an environmentally friendly procedure for the preparation of DHPMs and demonstrate the antioxidant capacity of some of the compounds.

Ultrasound irradiation promoted efficient solvent-free lipase-catalyzed production of mono- and diacylglycerols from olive oil

This work reports the enzymatic production of mono- and diacylglycerols under the influence of ultrasound irradiation, in a solvent-free system, with and without the presence of surfactants at a constant temperature of 65°C, glycerol to oil molar ratio of 2:1 and a commercial immobilized lipase (Novozym 435) as catalyst. For this purpose, two operation modes were adopted: the use of a sonotrode (ultrasonic probe), without agitation, varying reaction time, irradiation amplitude (25-45% of the total power) and type of surfactant, and a mechanically stirred reactor (600 rpm) under ultrasound irradiation in a water bath, testing different surfactants. Results show that very satisfactory MAG and DAG yields, above 50 wt.%, can be obtained without the use of surfactant, at mild irradiation power supply (∼130 W), with no important enzyme activity losses verified, in a relatively short reaction time (2h), and low enzyme content (7.5 wt.%). Also, reaction kinetic results show that contents of MAG+DAG as high as ∼65 wt.% can be achieved at longer times (6h), indicating a promising route for producing MAG and DAG using ultrasound irradiation.

Ultrasound-promoted synthesis of 3-trichloromethyl-5-alkyl(aryl)-1,2,4-oxadiazoles

The alternative synthesis of 12 1,2,4-oxadiazoles using ultrasound irradiation from trichloroacetoamidoxime and acyl chlorides is reported. Seven of them are novel compounds. The 3-trichloromethyl-5alkyl(aryl)-1,2,4-oxadiazoles have been synthesised in better yields and shorter reaction times compared to the conventional method. This protocol can be applicable for preparation of 1,2,4-oxadiazoles containing aryl or alkyl groups attached at their C-5 side-chain.

Ultrasound promoted greener synthesis of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles

A rapid and cleaner procedure for the synthesis of a series of 2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-phenylthiazoles under ultrasonic irradiation in ethanol is described.

Efficient sonochemical synthesis of thiazolidinones from piperonilamine

An efficient multicomponent reaction of arenealdehydes, mercaptoacetic acid and piperonilamine under ultrasound irradiation to afford 2-aryl-3-(piperonylmethyl)-1,3-thiazolidin-4-ones is reported. Applying this methodology, eleven heterocycles were synthesized and isolated in good yields after short reaction times.

Ultrasound promoted synthesis of thioesters from 2-mercaptobenzoxa(thia)zoles

An ultrasound-enhanced method has been developed for the synthesis of a variety of thioesters from benzoyl chlorides and 2-mercaptobenzoxa(thia)zoles. Applying this methodology, 14 compounds were synthesized in excellent yields.

Efficient sonochemical synthesis of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides

An ultrasound-assisted preparation of a series of novel 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamides that proceeds via the efficient reaction of chalcones with aminoguanidine hydrochloride under clean conditions is described.

Environmentally friendly sonocatalysis promoted preparation of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-1H-pyrazoles

An efficient and green synthesis of thiocarbamoyl-3,5-diaryl-4,5-dihydro-1H-pyrazoles via the condensation of chalcones with thiosemicarbazide in ethanol and KOH under ultrasound irradiation is reported. The products were isolated in good yields after short reaction times.

Ultrasound promoted synthesis of 5-hydroxy-5-trihalomethyl-4,5-dihydroisoxazoles and beta-enamino trihalomethyl ketones in water

A convenient method for the preparation of 5-hydroxy-5-trihalo-4,5-dihydroisoxazoles and beta-enamino trihalomethyl ketones, from the reaction of 1,1,1-trihalo-4-alkoxy-3-alken-2-ones with hydroxylamine and anilines, respectively, using water as solvent and under ultrasound irradiation is reported.

Dihydropyrimidin-(2H)-ones obtained by ultrasound irradiation: a new class of potential antioxidant agents

An efficient and simple synthetic protocol for the Biginelli reaction has been developed for the preparation of several new dihydropyrimidinones, under ultrasound irradiation in the presence of NH(4)Cl, in good yields and short reaction time. Some of the synthesized compounds were tested in vitro for their antioxidant activity. All of the selected compounds showed some antioxidant activity. Analogues compounds 3b and 4b exhibited a strong activity against lipid peroxidation induced by Fe + EDTA, while compounds 3b and 3d were the most potent in reducing ROS levels.