Assessing chemical constituents of Mimosa caesalpiniifolia stem bark: possible bioactive components accountable for the cytotoxic effect of M. caesalpiniifolia on human tumour cell lines.

Mimosa caesalpiniifolia is a native plant of the Brazilian northeast, and few studies have investigated its chemical composition and biological significance. This work describes the identification of the first chemical constituents in the ethanolic extract and fractions of M. caesalpiniifolia stem bark based on NMR, GC-qMS and HRMS analyses, as well as an assessment of their cytotoxic activity. GC-qMS analysis showed fatty acid derivatives, triterpenes and steroid substances and confirmed the identity of the chemical compounds isolated from the hexane fraction. Metabolite biodiversity in M. caesalpiniifolia stem bark revealed the differentiated accumulation of pentacyclic triterpenic acids, with a high content of betulinic acid and minor amounts of 3-oxo and 3ß-acetoxy derivatives. Bioactive analysis based on total phenolic and flavonoid content showed a high amount of these compounds in the ethanolic extract, and ESI-(-)-LTQ-Orbitrap-MS identified caffeoyl hexose at high intensity, as well as the presence of phenolic acids and flavonoids. Furthermore, the evaluation of the ethanolic extract and fractions, including betulinic acid, against colon (HCT-116), ovarian (OVCAR-8) and glioblastoma (SF-295) tumour cell lines showed that the crude extract, hexane and dichloromethane fractions possessed moderate to high inhibitory activity, which may be related to the abundance of betulinic acid. The phytochemical and biological study of M. caesalpiniifolia stem bark thus revealed a new alternative source of antitumour compounds, possibly made effective by the presence of betulinic acid and by chemical co-synergism with other compounds.

Cloning and purification of IpaC antigen from Shigella flexneri: proposal of a new methodology.

Shigella flexneri is a Gram-negative bacillus that is responsible for a severe form of dysentery called Shigellosis, which mainly affects children and the elderly in both underdeveloped and developed countries. Pathogenic S. flexneri strains possess a large virulence plasmid that codes for effector proteins that are required for the entry and spread of the bacteria into colonocytes. Among these proteins is the translocator IpaC, which plays an important role in the invasion process; IpaC is implicated in pore formation in the host cell membrane and induces cytoskeletal rearrangements in macrophages and epithelial cells, thereby promoting bacterial entry. The ability of IpaC to insert onto the plasma membrane is due to a large nonpolar region of the protein structure. This characteristic also renders difficulties in recovery and purification when the protein is expressed in E. coli. Several works have considered different methodologies for the improved production and purification of IpaC. Herein, we propose an alternative method that is based on changes in the induction temperature and extraction buffer to facilitate the accumulation of high yields of soluble proteins for their further processing and ultimate use in biotechnological approaches.

Development and validation of an LC-APCI-MS-MS analytical method for the determination of streptomycin and dihydrostreptomycin residues in milk.

An analytical method for the quantification and identity confirmation of streptomycin and dihydrostreptomycin residues in pasteurized milk using liquid chromatography (LC)-atmospheric pressure chemical ionization (APCI)-tandem mass spectrometry (MS-MS) was developed and validated. Method validation was performed according to the recommendations of the international agencies European Community and IUPAC, and the following parameters were evaluated: analytical curve, linearity, sensitivity, precision (intra- and inter-day repeatability), accuracy, and the limit of detection (LOD) and limit of quantification (LOQ). Simple sample preparation was followed by the LC-APCI-MS-MS analysis. The method presented adequate linearity with correlation coefficients above 0.99 for both analytes in the dynamic range of 50-400 microg/kg, and average accuracies between 84-110%. The LOD and LOQ were, respectively, 25 microg/kg and 50 microg/kg for both analytes. Method selectivity was verified by the absence of interfering peaks in the retention regions of the analytes and the internal standard when a blank sample was tested. The results qualified the method for the quantification and confirmation of the analytes in milk at concentrations inferior to the established maximum residue limits (200 microg/kg).

Medicamentos veterinários na apicultura: metodologias analíticas para determinação de resíduos no mel / Veterinary drugs on the apiculture: analytical methodologies for residues determination

There is an increasing demand for the determination of veterinary drug residues in honey. To determine these residues, many analytical techniques are available, but the high performance liquid chromatography has an important position, since it can be connected to different detectors in order to reach the required selectivity for the contaminant identification and quantification. Nowadays, mass spectrometry has become one of the most appropriated techniques to determinate veterinary drug residues in foods. However, the sample preparation is still a critical step in this kind of analysis. The present work is a review of the analytical methods that use high performance liquid chromatography for the determination of veterinary drug residues in honey, with emphasis on mass spectrometry and sample preparation.

Há uma demanda crescente para a determinação dos resíduos de medicamentos veterinários em mel. Para realizar essa determinação, diversas técnicas analíticas estão descritas. A cromatografia líquida de alta eficiência destaca- se entre as técnicas atualmente utilizadas devido a sua capacidade de separação e à possibilidade de acoplamento do cromatógrafo com diversos tipos de detectores a fim de obter a seletividade necessária para identificação e quantificação do(s) resíduo(s). Atualmente, a espectrometria de massas tem se mostrado a técnica de análise mais adequada para a identificação e quantificação de resíduos de medicamentos veterinários em alimentos. Entretanto, o preparo da amostra para análise é, ainda, a etapa crítica neste tipo de determinação. O presente trabalho faz uma revisão dos métodos anaíÌticos que utilizam acromatografia líquida de alta eficiência na determinação de resíduos de medicamentos veterinários em mel, com ênfase na utilização da espectrometria de massas e no preparo de amostra.

Medicamentos veterinários e a apicultura: aspectos comerciais, regulatórios e de saúde do consumidor / Veterinary drugs on the apiculture: commercial, regulatory and consumer health aspects

Apiculture is subject to attacks by plagues, which impair productivity of the apiary and, consequently, the revenue of the producer. To control these diseases veterinarian management techniques and the application of veterinary drugs such as oxytetracycline, chloramphenicol, streptomycin and sulfathiazole are employed. Nevertheless, residues of these antimicrobial agents can be present in honey, exposing the consumer to health risks in consequence of their ingestion. The aim of this work is to discuss the consequences of the use of veterinary drugs in the apiculture, considering the aspects related to consumers health, regulation and international trade of honey.

A apicultura esta sujeita ao ataque de pragas, que prejudicam a produtividade do apiário e, consequentemente, a lucratividade do produtor. Para combatê-las, são utilizadas técnicas de manejo e a aplicação de medicamentos veterinários como oxitetraciclina, cloranfenicol, estreptomicina e sulfatiazol. Entretanto, resíduos dessas substâncias podem estar presentes no mel, expondo os consumidores aos riscos consequentes da sua ingestão. Neste artigo são discutidas as consequências do uso de medicamentos veterinários na apicultura, considerando os aspectos relacionados à saúde do consumidor, à legislação vigente e o comércio internacional de mel.