Comparative performance of analytical techniques for polyhexamethylene biguanide (PHMB) in ophthalmic solutions

Purpose: The use of PHMB as a disinfectant in contact lens multipurpose solutions has been at the centre of much debate in recent times, particularly in relation to the issue of solution induced corneal staining. Clinical studies have been carried out which suggest different effects with individual contact lens materials used in combination with specific PHMB containing care regimes. There does not appear to be, however, a reliable analytical technique that would detect and quantify with any degree of accuracy the specific levels of PHMB that are taken up and released from individual solutions by the various contact lens materials. Methods: PHMB is a mixture of positively charged polymer units of varying molecular weight that has maximum absorbance wavelength of 236 nm. On the basis of these properties a range of assays including capillary electrophoresis, HPLC, a nickelnioxime colorimetric technique, mass spectrophotometry, UV spectroscopy and ion chromatography were assessed paying particular attention to each of their constraints and detection levels. Particular interest was focused on the relative advantage of contactless conductivity compared to UV and mass spectrometry detection in capillary electrophoresis (CE). This study provides an overview of the comparative performance of these techniques. Results: The UV absorbance of PHMB solutions, ranging from 0.0625 to 50 ppm was measured at 236 nm. Within this range the calibration curve appears to be linear however, absorption values below 1 ppm (0.0001%) were extremely difficult to reproduce. The concentration of PHMB in solutions is in the range of 0.0002–0.00005% and our investigations suggest that levels of PHMB below 0.0001% (levels encountered in uptake and release studies) can not be accurately estimated, in particular when analysing complex lens care solutions which can contain competitively absorbing, and thus interfering, species in the solution. The use of separative methodologies, such as CE using UV detection alone is similarly limited. Alternative techniques including contactless conductivity detection offer greater discrimination in complex solutions together with the opportunity for dual channel detection. Preliminary results achieved by TraceDec1 contactless conductivity detection, (Gain 150%, Offset 150) in conjunction with the Agilent capillary electrophoresis system using a bare fused silica capillary (extended light path, 50 mid, total length 64.5 cm, effective length 56 cm) and a cationic buffer at pH 3.2, exhibit great potential with reproducible PHMB split peaks. Conclusions: PHMB-based solutions are commonly associated with the potential to invoke corneal staining in combination with certain contact lens materials. However this terminology ‘PHMBbased solution’ is used primarily because PHMB itself has yet to be adequately implicated as the causative agent of the staining and compromised corneal cell integrity. The lack of well characterised adequately sensitive assays, coupled with the range of additional components that characterise individual care solutions pose a major barrier to the investigation of PHMB interactions in the lenswearing eye.

Lipophilic antifolates as potential antipsoriatic agents

The lipophilic dihydrofolate reductase (DHFR) inhibitor m-azidopyrimethamine (MZP) was investigated for suitability for development as a topical antipsoriatic agent. The clinical features and treatments for psoriasis were reviewed. High performance liquid chromatography (HPLC) was employed as the main analytical method, with UV spectroscopy being used in some cases. Reduction of the azido-group was proposed as a potential detoxification mechanism for MZP. The rates of reduction of a series of substituted phenyl azide compounds by dithiothreitol were investigated and found to depend on the substitution pattern of the aryl azide molecular, with electron deficient azides exhibiting faster rates of reduction in the system studied. The rates of reduction of MZP and analogous compounds were also studied using this model. The skin penetration of MZP was assessed using an in vitro hairless mouse skin model. The rate of permeation (flux) of MZP across hairless mouse skin was found to be dependent on the quantity of propylene glycol used as cosolvent in the vehicle and the pH. The use of a pretreatment regime of oleic acid in propylene glycol was shown to greatly increase the penetration of MZP through the hairless mouse skin as compared to application without pretreatment, or pretreatment with other penetration enhancers. The metabolism of MZP was studied in in vitro models comprising skin homogenates, SV-K14 human keratinocyte cell cultures and skin commensal bacterial cultures. No conversion of MZP to the corresponding amine was detected in any of the models. The growth inhibitory properties of MZP were investigated in an in vitro SV-K14 human keratinocyte cell culture model and compared with those of other DHFR inhibitors. [14C]-pyrimethamine was shown to be taken up by the SV-K14 keratinocytes.

A high sensitivity long period grating Mach-Zehnder refractometer

A refractive index sensing system has been demonstrated, which is based upon an in-line fibre long period grating Mach-Zehnder interferometer with a heterodyne interrogation technique. This sensing system has comparable accuracy to laboratory-based techniques used in industry such as high performance liquid chromatography and UV spectroscopy. The advantage of this system is that measurements can be made in-situ for applications in continuous process control. Compared to other refractive index sensing schemes using LPGs, this approach has two main advantages. Firstly, the system relies on a simple optical interrogation system and therefore has the real potential for being low cost, and secondly, so far as we are aware it provides the highest refractive index resolution reported for any fibre LPG device.

Detection of organic aromatic compounds in paraffin by a long-period fiber grating optical sensor with optimized sensitivity

A long-period grating (LPG) sensor is used to detect small variations in the concentration of an organic aromatic compound (xylene) in a paraffin (heptane) solution. A new design procedure is adopted and demonstrated to maximize the sensitivity of LPG (wavelength shift for a change in the surrounding refractive index, (dλ/dn3)) for a given application. The detection method adopted is comparable to the standard technique used in industry (high performance liquid chromatograph and UV spectroscopy) which has a relative accuracy between ∼±0.5% and 5%. The minimum detectable change in volumetric concentration is 0.04% in a binary fluid with the detection system presented. This change of concentration relates to a change in refractive index of Δn ∼ 6 × 10-5. © 2001 Elsevier Science B.V.

Avaliação da atividade anti-inflamatória do extrato aquoso, frações e compostos identificados nos frutos de Hancornia Speciosa Gomes (Apocynaceae)

Hancornia speciosa Gomes (Apocynaceae), popularly known as ‘mangabeira’, has been used in folk medicine to treat inflammatory disorders, hypertension, dermatitis, diabetes, liver diseases and stomach disorders. Regarding the Hancornia speciosa fruits, the ethnobotany indicates its use especially for treating inflammation and tuberculosis. However, no study has been done so far to prove such biological activities. The objective was evaluation anti-inflammatory activity from the fruits of Hancornia speciosa Gomes (mangabeira). Aqueous extract was prepared by decoction, subsequently submitted the liquid-liquid fractionation. The secondary metabolites were identified by high performance liquid chromatography coupled with detector diode array (HPLC-DAD) and liquid chromatography diode array detector coupled with mass spectrometry (LC-DAD-MS). The anti-inflammatory properties of the aqueous extract, dichloromethane (CH2Cl2), ethyl acetate (EtOAc) and n-butanol (n-BuOH) fractions of the fruits from H. speciosa, as well as rutin and chlorogenic acid were investigated using in vitro and in vivo models. In vivo tests comprised the xylene-induced ear edema that was measured the formation of edema, carrageenan-induced peritonitis was evaluated the total leukocytes at 4h and zymosan-induced air pouch was measured the total leukocytes and differential cell count at 6, 24 and 48 hours, whereas in vitro tests were evaluated levels of cytokines IL-1β, IL-6, IL-12 and TNF-α using ELISA obtained of carrageenan-induced peritonitis model. The results showed the presence of rutin and chlorogenic acid were detected in the aqueous extract from H. speciosa fruits by HPLC-DAD and LC-DAD-ME. Furthermore, the aqueous extracts and fractions, as well as rutin and chlorogenic acid significantly inhibited the xilol-induced ear edema and reduced cell migration in the animal models such as carrageenan-induced peritonitis and zymosan-induced air pouch. In addition, reduced levels of cytokines IL-1β, IL-6, IL-12 and TNF-α were observed. This is the first study that demonstrated the anti-inflammatory effect of aqueous extract from Hancornia speciosa fruits against different inflammatory agents in animal models, suggesting that their bioactive molecules, especially rutin and chlorogenic acid contributing, at least in part, to the anti-inflammatory effect of aqueous extract. These findings support the widespread use of Hancornia speciosa in popular medicine and demonstrate that this aqueous extract has therapeutic potential for the development of a herbal drugs with anti-inflammatory properties.

Microphytobenthos composition in Heron Reef, Australia, by High Performance Liquid Chromatography (HPLC) (July 2012)

We quantified pigment biomarkers by high performance liquid chromatography (HPLC) to obtain a broad taxonomic classification of microphytobenthos (MPB) (i.e. identification of dominant taxa). Three replicate sediment cores were collected at 0, 50 and 100 m along transects 5-9 in Heron Reef lagoon (n=15) (Fig. 1). Transects 1-4 could not be processed because the means to have the samples analysed by HPLC were not available at the time of field data collection. Cores were stored frozen and scrapes taken from the top of each one and placed in cryovials immersed in dry ice. Samples were sent to the laboratory (CSIRO Marine and Atmospheric Research, Hobart, Australia) where pigments were extracted with 100% acetone during fifteen hours at 4°C after vortex mixing (30 seconds) and sonication (15 minutes). Samples were then centrifuged and filtered prior to the analysis of pigment composition with a Waters - Alliance HPLC system equipped with a photo-diode array detector. Pigments were separated using a Zorbax Eclipse XDB-C8 stainless steel 150 mm x 4.6 mm ID column with 3.5 µm particle size (Agilent Technologies) and a binary gradient system with an elevated column temperature following a modified version of the Van Heukelem and Thomas (2001) method. The separated pigments were detected at 436 nm and identified against standard spectra using Waters Empower software. Standards for HPLC system calibration were obtained from Sigma (USA) and DHI (Denmark).

Influence of serum levels of vitamins A, D, and E as well as vitamin D receptor polymorphisms on micronucleus frequencies and other biomarkers of genotoxicity in workers exposed to formaldehyde

Background/Aim: Formaldehyde is classified as carcinogenic to humans, making it a major concern, particularly in occupational settings. Fat-soluble vitamins, such as vitamins A, D, and E, are documented as antigenotoxic and antimutagenic and also correlate with the cell antioxidant potential. This study investigates the influence of these vitamins on genotoxicity biomarkers of formaldehyde-exposed hospital workers. Methods: The target population were hospital workers exposed to formaldehyde (n = 55). Controls were nonexposed individuals (n = 80). The most used genotoxicity biomarkers were the cytokinesis-block micronucleus assay for lymphocytes and the micronucleus test for exfoliated buccal cells. Vitamins A and E were determined by high-performance liquid chromatography with a diode array detector (HPLC-DAD) and vitamin D receptor (VDR) polymorphisms by real-time PCR. Results: Significant correlations were found between genotoxicity biomarkers and between vitamins A and E in controls. Multiple regression showed that vitamin A was significantly associated with a higher mean of nucleoplasmic bridges (p < 0.001), and vitamin E was significantly associated with a decreased frequency of nuclear buds (p = 0.045) in the exposed group. No effect of vitamin D was observed. The VDRBsmI TT genotype carriers presented higher means of all the genotoxicity biomarkers; however, we found no significant associations. Conclusions: The study suggests that vitamin levels may modulate direct signs of genotoxicity.

Otimização e validação de métodos empregando DLLME, SPE, HPLC-DAD e LC-ESI-MS/MS para determinação de agrotóxicos em água subterrânea

A preocupação com a poluição das águas por agrotóxicos tem aumentado, visto que aumentou o número de detecções de agrotóxicos em águas. A falta de avaliação da qualidade da água consumida pela população de áreas rurais onde não existe o abastecimento público de água potável, deve ser considerada, pois essas águas se encontram próximo a áreas de cultivo, onde há intensa aplicação de agrotóxicos. Nessas regiões, o abastecimento de água para as residências e para a irrigação é feito geralmente através das águas de poços. Neste trabalho, um método para determinação dos agrotóxicos carbofurano, clomazona, 2,4-D e tebuconazol em água subterrânea foi desenvolvido e validado. O método utilizou a Extração em Fase Sólida (SPE) e determinação por Cromatografia Líquida de Alta eficiência com Detecção por Arranjo de Diodos (HPLC-DAD) e confirmação por Cromatografia Líquida tandem Espectrometria de Massas (LC-MS/MS). Para a SPE utilizou-se cartuchos C18 de 200 mg, e eluição com 1 mL de metanol. Após a otimização dos parâmetros de extração e separação dos compostos, o método foi validado avaliando-se curva analítica, linearidade, limites de detecção e quantificação, precisão (repetitividade e precisão intermediária) e exatidão (recuperação). Todas as curvas analíticas apresentaram valores de r maiores que 0,99. Os LOQs para o método, considerando a etapa de pré-concentração de 250 vezes, foram de 0,2 µg L -1 para todos os agrotóxicos por HPLC-DAD e, por LC-MS/MS, 4,0 ng L -1 para clomazona, carbofurano e tebuconazol e de 40,0 ng L -1 para 2,4-D. As recuperações foram entre 60,3 e 107,7% para a repetitividade e entre 67,5 e 115,3% para a precisão intermediária, com RSD de 0,8 a 20,7% para todos os compostos por HPLC-DAD. Para o LC-MS/MS a precisão em termos de repetitividade, variou entre 0,97 e 20,7%, e as recuperações entre 67,0 e 108,9%. O método foi aplicado na determinação de agrotóxicos em amostras de águas subterrâneas durante um ano. Nas amostras foram detectados agrotóxicos em níveis de µg L -1 . Dentro do contexto atual da Química Analítica, de desenvolver métodos mais rápidos, que utilizem menor quantidade de solvente, de amostra e com altos fatores de enriquecimento, foi otimizado um método de extração para os agrotóxicos carbofurano, clomazona e tebuconazol utilizando a Microextração Líquido-Líquido Dispersiva (DLLME) e determinação por LC-MS/MS. Foram otimizados alguns parâmetros que influenciam no processo de extração, como: tipo e volume dos solventes dispersores e extratores, tempo de extração, força iônica e velocidade de centrifugação. Nas condições otimizadas, as recuperações para os níveis de concentração entre 0,02 e 2,0 g L -1 variaram entre 62,7 e 120,0%, com valores de RSD entre 1,9 e 9,1%. O LOQ do método foi de 0,02 µg L -1 para todos os compostos. Quando comparado com a SPE se demonstrou rápido, simples, de baixo custo, além de necessitar de menores volumes de amostra para determinação de agrotóxicos em águas. O método mostrou-se adequado à análise dos agrotóxicos em água subterrânea e todos os parâmetros de validação obtidos estão dentro dos limites sugeridos para validação de métodos cromatográficos

A prospective study on bioactive properties of wild mushrooms mycelium grown in vitro under different conditions

Wild mushrooms have been extensively studied for their value as sources of high quality nutrients and of powerful physiologically bioactive compounds [1,2]. The present study was designed to evaluate the in vitro development of two wild edible mushroom species: Pleurotus eryngii (DC.) Quél. and Suillus belinii (Inzenga) Watling, by testing different solid (Potato Dextrose Agar medium –PDA and Melin-Norkans medium- MMN) and liquid culture media (Potato dextrose broth- PDB and Melin-Norkans medium- MMN). Each strain of mushroom produces a special type of mycelium and this range of characteristics varies in form, color and growth rate. S. bellinii presents a pigmented and rhizomorphic mycelia, whereas, P. eryngii has depigmented and cottony mycelia. The mycelium isolated and grown in PDA showed a faster radial growth compared to the mycelium isolated and grown in both solid and liquid incomplete MMN medium. P. eryngii exhibited a rapid growth and a higher mycelia biomass in both medium compared to S. belinii. Moreover, the obtained mycelia will be characterized in terms of well-recognized bioactive compounds namely, phenolic acids and mycosterols (mainly ergosterol), by using high performance liquid chromatography coupled to diode array and ultraviolet detectors, respectively. These compounds will be correlated to mycelia bioactivity: i) antioxidant activity, evaluated through free radicals scavenging activity, reducing power and lipid peroxidation inhibition in vitro assays; ii) anti-inflammatory activity, assessed through nitric oxide production inhibition in murine macrophages (RAW 264.7 cell line); iii) cytotoxic activity, evaluated either in human tumor cell lines (MCF-7- breast adenocarcinoma, NCIH460- non-small cell lung cancer, HeLa- cervical carcinoma and HepG2- hepatocellular carcinoma) as also in a non-tumor porcine primary liver cells culture established in-house (PLP2). Overall, our expectation is that the bioactive formulations obtained by in vitro culture can be applied as nutraceuticals or incorporated in functional foods.

HPLC-DAD-ESI/MS phenolic characterization and biological activity of Equisetum giganteum L.

Naturally-occurring phytochemicals have received a pivotal attention in the last years, due to the increasing evidences of biological activities. Equisetum giganteum L., commonly known as “giant horsetail”, is a native plant from Central and South America, being largely used in dietary supplements as diuretic, hemostatic, antiinflammatory and anti-rheumatic agents [1,2]. The aim of the present study was to evaluate the antioxidant (scavenging effects on 2,2-diphenyl-1-picrylhydrazyl radicals- RSA, reducing power- RP, β-carotene bleaching inhibition- CBI and lipid peroxidation inhibition- LPI), anti-inflammatory (inhibition of NO production in lipopolysaccharidestimulated RAW 264.7 macrophages) and cytotoxic (in a panel of four human tumor cell lines: MCF-7- breast adenocarcinoma, NCI-H460- non-small cell lung cancer, HeLa- cervical carcinoma and HepG2- hepatocellular carcinoma; and in non-tumor porcine liver primary cells- PLP2) properties of E. giganteum, providing a phytochemical characterization of its extract (ethanol/water, 80:20, v/v), by using highperformance liquid chromatography coupled to diode array detection and electrospray ionisation mass spectrometry (HPLC-DAD–ESI/MS). E. giganteum presented fourteen phenolic compounds, two phenolic acids and twelve flavonol glycoside derivatives, mainly kaempferol derivatives, accounting to 81% of the total phenolic content, being kaempferol-O-glucoside-O-rutinoside, the most abundant molecule (7.6 mg/g extract). The extract exhibited antioxidant (EC50 values = 123, 136, 202 and 57.4 μg/mL for RSA, RP, CBI and LPI, respectively), anti-inflammatory (EC50 value = 239 μg/mL) and cytotoxic (GI50 values = 250, 258, 268 and 239 μg/mL for MCF-7, NCI-H460, HeLa and HepG2, respectively) properties, which were positively correlated with its concentration in phenolic compounds. Furthermore, up to 400 μg/mL, it did not revealed toxicity in non-tumor liver cells. Thus, this study highlights the potential of E. giganteum extracts as rich sources of phenolic compounds that can be used in the food, pharmaceutical and cosmetic fields.

Chromatographic analysis of antioxidant and related compounds in Polyporus squamosus from different origins

The antioxidant potential of mushrooms is mainly attributed to their composition in polysaccharides, phenolic compounds, tocopherols and some organic acids [1]. Phenolic compounds contribute directly to the antioxidative action and play an important role in stabilizing lipid peroxidation [2]; exhibit a wide range of bioactive properties such as anti-allergenic, anti-inflammatory and antimicrobial, which have been in part related to their antioxidant activity [3]. Tocopherols are important fatsoluble antioxidants, acting in the cellular membrane; due to their role as scavenger of free radicals protecting human cells against degenerative malfunctions [4]. Some organic acids are very common in natural matrices; malic acid contributes to a pleasantly sour taste and is often used as a food additive; citric acid is known due to its antibacterial and antioxidant properties and fumaric acid is important because of its antioxidant, anti-inflammatory, antimicrobial and acidifying properties [5]. The purpose of the present study was to analyze antioxidant and related compounds (phenolic compounds, tocopherols and organic acids) of Polyporus squamosus (Huds.) Fr. samples originated from two different origins (Portugal and Serbia). Specimens of P. squamosus were collected in Bragança (Northeast Portugal) and Jabučki rit (Northern Serbia) during April 2015 and 2012, respectively. Phenolic compounds, organic acids and tocopherols were determined by high performance liquid chromatograph (HPLC) coupled to a diode array detector (DAD), in the two first cases, and a fluorescence detector in the last one. With respect to phenolic and related compounds, p-hydroxybenzoic and cinnamic acids were identified in both samples; the first one predominates in the sample from Portugal, while cinnamic acid was more abundant in the sample from Serbia. Tocopherols (α-, β and γ-isoforms) were found in the sample from Serbia, but in the sample from Portugal, γ-tocopherol was not identified. This sample showed the highest total tocopherols content, and revealed the highest level of β-tocopherol; γ- tocopherol predominated in the sample from Serbia. Among organic acids, it was possible to quantify oxalic, malic and fumaric acids in both samples. Malic acid was found in higher amounts in the sample from Serbia. Overall, the present study shows that mushroom samples from different origins have dissimilar results, but are both rich in bioactive compounds, being a valuable source for the development of natural medicines and nutraceuticals.

Non-fermented and fermented jabuticaba (Myrciaria cauliflora Mart.) pomaces as valuable sources of functional ingredients

abuticaba (Myrciaria cauliflora. Mart) is a highly perishable fruit native to Brazil, which is consumed both fresh and industrially processed in the form of juices, jams, wines and distilled liqueurs. This processing generates a large amount of waste by-products, which represent approximately 50% of the fruit weight. The by-products are of interest for obtaining valuable bioactive compounds that could be used as nutraceuticals or functional ingredients. In this study, fermented and non-fermented jabuticaba pomaces were studied regarding their hydrophilic and lipophilic compounds, as well as their antioxidant properties, including: soluble sugars, organic acids and tocopherols (using high performance liquid chromatography coupled to refraction index, diode array and fluorescence detector, respectively); phenolics and anthocyanins, (using liquid chromatography coupled to diode array detection, and mass spectrometry with electrospray ionization); and fatty acids (using gas-liquid chromatography with flame ionization detection). The analytical data demonstrated that jabuticaba pomaces are a rich source of bioactive compounds such as tocopherols, polyunsaturated fatty acids and phenolic compounds (namely hydrolyzable tannins and anthocyanins) with antioxidant potential. Therefore, jabuticaba pomace may have good potential as a functional ingredient in the fabrication of human foods and animal feed.

In vivo antileishmanial activity and chemical profile of polar extract from Selaginella sellowii

The polar hydroethanolic extract from Selaginella sellowii (SSPHE) has been previously proven active on intracellular amastigotes (in vitro test) and now was tested on hamsters infected with Leishmania (Leishmania) amazonensis (in vivo test). SSPHE suppressed a 100% of the parasite load in the infection site and draining lymph nodes at an intralesional dose of 50 mg/kg/day × 5, which was similar to the results observed in hamsters treated with N-methylglucamine antimonate (Sb) (28 mg/Kg/day × 5). When orally administered, SSPHE (50 mg/kg/day × 20) suppressed 99.2% of the parasite load in infected footpads, while Sb suppressed 98.5%. SSPHE also enhanced the release of nitric oxide through the intralesional route in comparison to Sb. The chemical fingerprint of SSPHE by high-performance liquid chromatography with diode-array detection and tandem mass spectrometry showed the presence of biflavonoids and high molecular weight phenylpropanoid glycosides. These compounds may have a synergistic action in vivo. Histopathological study revealed that the intralesional treatment with SSPHE induced an intense inflammatory infiltrate, composed mainly of mononuclear cells. The present findings reinforce the potential of this natural product as a source of future drug candidates for American cutaneous leishmaniasis.

Desenvolvimento e validação de métodos para a determinação de agrotóxicos em água e solo das áreas de recarga de Aquífero Guarani, na região das nascentes do Rio Araguaia, MT/GO.

Abstract: The area near the Araguaia River, between Goiás and Mato Grosso States, is the location of a portion of the recharging of the Guarani Aquifer, which is one of the world¿s largest aquifer systems and an important source of drinking water. This reservoir could be threatened by the widespread use of pesticides in maize and soybean cultivation in this area. Thus, this work developed analytical methods for the determination of imazethapyr, nicosulfuron, imazaquin, carbofuran, atrazine, linuron, clorimuronethyl and diflubenzuron, pesticides used in maize and soybean cultivation. Pesticide separation, identification and quantification were performed using High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD) and Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS). Solid Phase Extraction (SPE) with C18 sorbents was optimized for sample extraction from water. Soil samples were extracted by mechanical shaking, sonication or microwave-assisted extraction with industrial and home microwave ovens. Methods were validated resulting in limits of quantification (LOQ) for the pesticides in water in the range of 0.015-0.1 ng mL, using SPE-HPLC-DAD, and 0.01 ng mL using LC-ESI-MS/MS. LOQ of 1 ng mL for all pesticides in soil were achieved using the home microwave oven and LC-ESI-MS/MS. Recoveries for pesticides with all methods were in the range 70-120 %. Relative standard deviations for repeatability and intermediate precision were less than 15 %. SPEHPLC- DAD and LC-ESI-MS/MS were employed for the analysis of samples of water from the recharge area and most of the pesticides were detected at concentrations below the minimum residue limit (MRL) of 0.1 ng mL established by the European Community. The home microwave oven and LC-ESI-MS/MS were used for the analysis of soil samples from two other regions of Brazil and the pesticides were not detected in these samples. Adsorption and desorption parameters were determined for imazethapyr, imazaquin, nicosulfuron and chlorimuron-ethyl, indicating that these pesticides have little affinity for the soil of the region of the Guarani Aquifer recharge, and show significant leaching potential, according to the ground water ubiquity score (GUS index) for these pesticides.

Synthesis and antibacterial profile of novel azomethine derivatives of β-phenylacrolein moiety

Purpose: To develop some novel molecules effective against antibiotic-resistant bacterial infections. Methods: A series of azomethines (SB-1 to SB-6) were synthesized from β-phenyl acrolein moiety. The structures of the synthesized compounds were confirmed on the basis of their UV ultra-violet (UV) spectroscopy (λmax: 200 - 400 nm), Fourier transform infra-red (FTIR, vibrational frequency: 500-4000 cm-1), 1H nuclear magnetic resonance (NMR, chemical shift: 0 - 10 ppm), 13C NMR (chemical shift: 0 - 200 ppm), mass spectrometry (m/z values: 0 - 500) and carbon hydrogen nitrogen (CHN) elemental analysis. The new compounds were screened for antibacterial activity by test-tube dilution and disc diffusion methods using gentamicin as reference standard. Results: The structures of azomethine were in full agreement with their spectral data. Among all the synthesized compounds, compounds SB-5 and SB-6 exhibited the highest minimum inhibitory concentration (MIC) of 62.5 μg/mL. At MIC of 250 μg/mL, all compounds SB-1 to SB-6 displayed significant antibacterial activity, compared to gentamycin (p < 0.05). SB-5 and SB-6 were active against S. aureus, P. aeruginosa and K. pneumoniae; SB-3 was active against B. subtilis and S. aureus. SB-4 was active against P. aeruginosa and S. aureus while SB-1 and SB-2 were active against S. aureus. Conclusion: The synthesized compounds possess antibacterial activities compared to those of gentamycin.