Three New Polyprenylated Benzophenone Derivatives Isolated from Clusia burle-marxii.

Three new polyprenylated benzophenone derivatives named burlemarxione G-I (1-3) were isolated from C. burle-marxii trunks (compound 1) and leaves (compounds 2 and 3), along with the known compound burlemarxione F. Burlemarxione G (1) was isolated after methylation with diazomethane and it is the keto-enol tautomeric pair of burlemarxione F. Burlemarxione H (2) derives from burlemarxiones F and G, but it has additional rings due to cyclization of the prenyl group attached to C-5 that establishes new single bonds between C-1 and C-23, as well as, between C-24 and C-29. Burlemarxione I (3) has two additional cyclizations: the first encompasses the cyclization of the former isopentenyl group into an 11,11-dimethyl-six-membered ring, whereas the second produces additional rings due to the cyclization of the prenyl group attached to C-5 that establishes new single bonds between C-1 and C-23, as well as, between C-24 and C-29. All three compounds showed moderate anti-glioma activity. These results show that C. burle-marxii is an important source of sophisticated polyprenylated benzophenone derivatives.

Litter Size Reduction Induces Metabolic and Histological Adjustments in Dams throughout Lactation with Early Effects on Offspring.

In the present study we analyzed morphological and metabolic alterations in dams nursing small litters and their consequences to offspring throughout lactation. Offspring sizes were adjusted to Small Litter (SL, 3 pups/ dam) and Normal Litter (NL, 9 pups/ dam). Body weight, food intake, white adipose tissue (WAT) content, histological analysis of the pancreas, mammary gland (MG) and brown adipose tissue (BAT) as well as, plasma parameters and milk composition were measured in dams and pups on the 7th, 14th and 21st days of lactation. In general, SL-dams presented higher body weight and retroperitoneal fat content, elevated fat infiltration in BAT, reduced islets size and hyperglycemia throughout lactation in relation to NL-dams (p<0.05). Moreover, MG from SL-dams had reduced alveoli development and high adipocytes content, resulting in milk with elevated energetic value and fat content in relation to NL-dams (p<0.05). Maternal states influenced offspring anthropometric conditions during lactation, offspring-SL displayed higher body weight and growth, hyperglycemia, augmented lipid deposition in BAT and elevated islet. Thus, maternal histological and metabolic changes are due to modifications to nursing small litters and reinforce the importance of preserving maternal health during lactation avoiding early programming effects on offspring preventing metabolic consequences later in life.

Physiological and biochemical responses of Ricinus communis seedlings to different temperatures: a metabolomics approach.

BACKGROUND: Compared with major crops, growth and development of Ricinus communis is still poorly understood. A better understanding of the biochemical and physiological aspects of germination and seedling growth is crucial for the breeding of high yielding varieties adapted to various growing environments. In this context, we analysed the effect of temperature on growth of young R. communis seedlings and we measured primary and secondary metabolites in roots and cotyledons. Three genotypes, recommended to small family farms as cash crop, were used in this study. RESULTS: Seedling biomass was strongly affected by the temperature, with the lowest total biomass observed at 20°C. The response in terms of biomass production for the genotype MPA11 was clearly different from the other two genotypes: genotype MPA11 produced heavier seedlings at all temperatures but the root biomass of this genotype decreased with increasing temperature, reaching the lowest value at 35°C. In contrast, root biomass of genotypes MPB01 and IAC80 was not affected by temperature, suggesting that the roots of these genotypes are less sensitive to changes in temperature. In addition, an increasing temperature decreased the root to shoot ratio, which suggests that biomass allocation between below- and above ground parts of the plants was strongly affected by the temperature. Carbohydrate contents were reduced in response to increasing temperature in both roots and cotyledons, whereas amino acids accumulated to higher contents. Our results show that a specific balance between amino acids, carbohydrates and organic acids in the cotyledons and roots seems to be an important trait for faster and more efficient growth of genotype MPA11. CONCLUSIONS: An increase in temperature triggers the mobilization of carbohydrates to support the preferred growth of the aerial parts, at the expense of the roots. A shift in the carbon-nitrogen metabolism towards the accumulation of nitrogen-containing compounds seems to be the main biochemical response to support growth at higher temperatures. The biochemical changes observed in response to the increasing temperature provide leads into understanding plant adaptation to harsh environmental conditions, which will be very helpful in developing strategies for R. communis crop improvement research.

Amburana cearensis seed extract stimulates astrocyte glutamate homeostatic mechanisms in hippocampal brain slices and protects oligodendrocytes against ischemia.

BACKGROUND: Stroke is a leading cause of death and disability worldwide. A major factor in brain damage following ischemia is excitotoxicity caused by elevated levels of the neurotransmitter glutamate. In the brain, glutamate homeostasis is a primary function of astrocytes. Amburana cearensis has long been used in folk medicine and seed extract obtained with dichloromethane (EDAC) have previously been shown to exhibit cytoprotective activity in vitro. The aim of the present study was to analyse the activity of EDAC in hippocampal brain slices. METHODS: We prepared a dichloromethane extract (EDAC) from A. cearensis seeds and characterized the chemical constituents by 1H and 13C-NMR. Hippocampal slices from P6-8 or P90 Wistar rats were used for cell viability assay or glutamate uptake test. Hippocampal slices from P10-12 transgenic mice SOX10-EGFP and GFAP-EGFP and immunofluorescence for GS, GLAST and GLT1 were used to study oligodendrocytes and astrocytes. RESULTS: Astrocytes play a critical role in glutamate homeostasis and we provide immunohistochemical evidence that in excitotoxicity EDAC increased expression of glutamate transporters and glutamine synthetase, which is essential for detoxifying glutamate. Next, we directly examined astrocytes using transgenic mice in which glial fibrillary acidic protein (GFAP) drives expression of enhanced green fluorescence protein (EGFP) and show that glutamate excitotoxicity caused a decrease in GFAP-EGFP and that EDAC protected against this loss. This was examined further in the oxygen-glucose deprivation (OGD) model of ischemia, where EDAC caused an increase in astrocytic process branching, resulting in an increase in GFAP-EGFP. Using SOX10-EGFP reporter mice, we show that the acute response of oligodendrocytes to OGD in hippocampal slices is a marked loss of their processes and EDAC protected oligodendrocytes against this damage. CONCLUSION: This study provides evidence that EDAC is cytoprotective against ischemia and glutamate excitotoxicity by modulating astrocyte responses and stimulating their glutamate homeostatic mechanisms.

Testicular volume and Tanner stage: determinant factors for testicular torsion.

OBJECTIVE: To assess testicular volumes and sexual maturation in patients with testicular torsion. METHODS: A retrospective analysis of consecutively treated patients with testicular torsion between 2016 and 2018. Age, pubic hair staging (Tanner), and by ultrasonography, volume of the unaffected testis (in cubic centimeters) were evaluated either immediately before surgery or at the first postoperative visit. Patients with previous testicular disease, such as cryptorchidism, or with no records of testicular volume were excluded. The analysis included descriptive statistics and Bayesian regression. RESULTS: We treated 149 patients during the study period, and 141 (94.6%, median age 17.3 years) met the inclusion criteria. Median testicular volume was 13.0cm3 (interquartile range of 10.5-15.2), with similar right and left volumes (12.9cm3versus 13.3cm3; p=0.94). Sixty-five (46.1%) patients were Tanner stage IV, 17 (12.1%) stage III, and 59 (41.8%) stage V. CONCLUSION: In this study, we were able to estimate volumes of testicular torsion, which aggregated around late puberty values (13.0cm3 for the whole dataset, 12.2cm3 for patients <25 years), suggesting that testicular hypermobility, due to congenital anatomical abnormalities, remains quiescent until the organ reaches a critical volume, after which torsion becomes possible. These findings provide a tentative explanation for the disease's age distribution.

Influence of red propolis on the physicochemical, microbiological and sensory characteristics of tilapia (Oreochromis niloticus) salami.

To reduce the number of preservatives in foods, this study evaluated the oxidative, microbiological, and sensory stability of fish salami containing a red propolis hydroalcoholic extract (RPHE) in place of the butyl hydroxytoluene (BHT) antioxidant. Initially, the RPHE was characterized chemically and biologically. Subsequently, the antimicrobial and physicochemical activity of the most accepted salami formulation in sensory analysis (F3 = 0.4% RPHE) and of the control formulations (F1 = 0.01% BHT and F5 = without antioxidant) were evaluated during the maturation. RPHE showed promising biological activity. 16 chemical compounds were identified in the RPHE, including the chemical marker formononetin. Salami with 0.4% RPHE showed high sensory acceptance and effectively delayed deterioration (19.67 mg TVB-N 100/g) and lipid oxidation of salami (0.7 mg MDA eq/kg). The use of RPHE as a natural preservative is promising to produce fish salami.

A sodium alginate bilayer coating incorporated with green propolis extract as a powerful tool to extend Colossoma macropomum fillet shelf-life.

Fish deterioration imposes great economic losses and serious human health hazards. The objective of this work was to evaluate the effect of a sodium alginate bilayer coating incorporated to the green propolis extract in shelf-life, physical-chemical properties, microbiological properties and sensory acceptance of Colossoma macropomum fillets. Additionally, the chemical composition, along with the antioxidant and antibacterial activities of Brazilian green propolis extract (GPE) were investigated. GPE showed promising antioxidant and antibacterial activities. Twenty-seven metabolites were identified by gas chromatography (GC-MS), which mainly comprised terpenoids (52.14%). Cyclolaudenol was the major constituent of the GPE and it is described for the first time in green propolis extracts. C. macropomum fillets treated with the sodium alginate bilayer coating showed high sensory acceptance, reduced microbial deterioration and extended shelf-life (up to 11 days) during cold storage. Taken together, these results show that GPE can be a great alternative of a natural preservative for fish coating.

Synthesis of a Glibenclamide Cocrystal: Full Spectroscopic and Thermal Characterization.

A cocrystal of glibenclamide, an antidiabetic drug classified as type II compound according to the Biopharmaceutics Classification System, has been synthesized using tromethamine as coformer in 1:1 molar ratio, by slow solvent evaporation cocrystalization. The cocrystal obtained was characterized by X-ray powder diffraction, differential scanning calorimetry, Raman, mid infrared, and near-infrared spectroscopy. The results consistently show the formation of a cocrystal between active pharmaceutical ingredients and conformer with the synthons corresponding to hydrogen bonding between hydrogen in amines of tromethamine and carbonyl and sulfonyl groups in glibenclamide.

Selection of plants for phytoremediation of barium-polluted flooded soils.

The use of barite (BaSO4) in drilling fluids for oil and gas activities makes barium a potential contaminant in case of spills onto flooded soils, where low redox conditions may increase barium sulfate solubility. In order to select plants able to remove barium in such scenarios, the following species were evaluated on barium phytoextraction capacity: Brachiaria arrecta, Cyperus papyrus, Eleocharis acutangula, E. interstincta, Nephrolepsis cf. rivularis, Oryza sativa IRGA 424, O. sativa BRS Tropical, Paspalum conspersum, and Typha domingensis. Plants were grown in pots and exposed to six barium concentrations: 0, 2.5, 5.0, 10.0, 30.0, and 65.0 mg kg-1. To simulate flooding conditions, each pot was kept with a thin water film over the soil surface (∼1.0 cm). Plants were evaluated for biomass yield and barium removal. The highest amount of barium was observed in T. domingensis biomass, followed by C. papyrus. However, the latter exported most of the barium to the aerial part of the plant, especially at higher BaCl2 doses, while the former accumulated barium preferentially in the roots. Thus, barium removal with C. papyrus could be achieved by simply harvesting aerial biomass. The high amounts of barium in T. domingensis and C. papyrus resulted from the combination of high barium concentration in plant tissues with high biomass production. These results make T. domingensis and C. papyrus potential candidates for phytoremediation schemes to remove barium from flooded soils.

Testicular volume and Tanner stage: determinant factors for testicular torsion

ABSTRACT Objective To assess testicular volumes and sexual maturation in patients with testicular torsion. Methods A retrospective analysis of consecutively treated patients with testicular torsion between 2016 and 2018. Age, pubic hair staging (Tanner), and by ultrasonography, volume of the unaffected testis (in cubic centimeters) were evaluated either immediately before surgery or at the first postoperative visit. Patients with previous testicular disease, such as cryptorchidism, or with no records of testicular volume were excluded. The analysis included descriptive statistics and Bayesian regression. Results We treated 149 patients during the study period, and 141 (94.6%, median age 17.3 years) met the inclusion criteria. Median testicular volume was 13.0cm3 (interquartile range of 10.5-15.2), with similar right and left volumes (12.9cm3versus 13.3cm3; p=0.94). Sixty-five (46.1%) patients were Tanner stage IV, 17 (12.1%) stage III, and 59 (41.8%) stage V. Conclusion In this study, we were able to estimate volumes of testicular torsion, which aggregated around late puberty values (13.0cm3 for the whole dataset, 12.2cm3 for patients <25 years), suggesting that testicular hypermobility, due to congenital anatomical abnormalities, remains quiescent until the organ reaches a critical volume, after which torsion becomes possible. These findings provide a tentative explanation for the disease's age distribution.

Amburana cearensis seed extract protects brain mitochondria from oxidative stress and cerebellar cells from excitotoxicity induced by glutamate.

ETHNOPHARMACOLOGICAL RELEVANCE: Amburana cearensis (Allemao) A.C.Sm. is a medicinal plant of the Brazilian Caatinga reported to present antioxidant and anti-inflammatory activity. This study aimed to evaluate the neuroprotective effect of the extracts obtained from the seeds of A. cearensis in primary cultures of cerebellar cells subjected to excitotoxicity induced by glutamate and brain mitochondria submitted to oxidative stress. MATERIALS: and methods: Primary cultures of cerebellar cells were treated with the ethanol (ETAC), hexane (EHAC), dichloromethane (EDAC) and ethyl acetate (EAAC) extracts of the seeds of A.cearensis and subjected to excitotoxicity induced by glutamate (10µM). Mitochondria isolated from rat brains were submitted to oxidative stress and treated with ETAC. RESULTS: Only the EHAC extract reduced cell viability by 30% after 72h of treatment. Morphological analyses by Immunofluorescence showed positive staining for glutamine synthetase, ß-III tubulin, GFAP and IBA1 similar to control cultures, indicating a better preservation of astrocytes, neurons and microglia, after excitotoxic damage induced by glutamate in cerebellar cultures treated with the extracts. The ETAC extract also protected mitochondria isolated from rat brains from oxidative stress, reducing the swelling, dissipation of the membrane potential, ROS production and calcium influx. CONCLUSION: Thus, this study suggests that the seed extracts from A. Cearensis exhibit neuroprotective potential against oxidative stress and excitotoxicity induced by glutamate and can be considered a potential therapeutic agent in the treatment of neurodegenerative diseases.

Near infrared spectroscopy to monitor drug release in-situ during dissolution tests.

Dissolution tests can be used to demonstrate suitable in vivo drug release through in vivo/in vitro correlations. This work explores the possibility of using near infrared spectroscopy (NIRS) to monitor in-situ dissolution tests. It aims at expanding surrogate methods in quality control of drug products. Laboratory designed tablets of an immediate-release formulation containing folic acid and four excipients were used as case study. The dissolution tests were performed on a 1L vessel filled with 500ml of Milli-Q water with a rotating paddle apparatus (apparatus 2, Ph. Eur.) at 50rpm and 37±0.5°C. Near infrared (NIR) spectra were acquired in-situ with a transflectance probe connected to a Fourier-transform near infrared spectrometer. NIR spectra were regressed against folic acid concentration by partial least squares (PLS) regression. Folic acid concentrations during dissolution tests were obtained by periodically sampling the dissolution vessel and resourcing to an UV method. The proposed real-time NIR method was tested on a validation run yielding a root mean squared error of 0.25µgml-1 (0.16µgml-1 for the calibration runs) and a R2 of 0.93 (0.95 for the calibration runs). The results suggest that NIRS is a suitable analytical technique for monitoring in-situ dissolution tests.

Phytochemical screening, antioxidant and antibacterial activities of extracts prepared from different tissues of Schinus terebinthifolius Raddi that occurs in the coast of Bahia, Brazil.

BACKGROUND: Schinus terebinthifolius is widely used in traditional medicine by Brazilian quilombola and indigenous communities for treatment of several diseases. Extracts from different tissues are being used to produce creams to treat cervicitis and cervicovaginitis. However, most studies are limited to the assessment of the essential oils and extracts obtained from the leaves. OBJECTIVE: The aim was to evaluate antioxidant and antibacterial activities, to assess the phytochemical profile and to quantify total phenolic compounds of various extracts prepared from S. terebinthifolius grown in the coast of Bahia, Brazil. MATERIALS AND METHODS: Extracts were obtained by hot continuous extraction (soxhlet) and by maceration. Quantification of phenolic compounds was performed using the Folin-Ciocalteu method and antioxidant properties were assessed by 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Phytochemical screening was performed as described by in the literature and antibacterial activity against Enterococcus faecalis (ATCC 29212) was determined by the microdilution broth assay. RESULTS: Extraction method greatly affected the metabolite profile of the extracts. Antioxidant activity varied between 21.92% and 85.76%, while total phenols ranged between 5.44 and 309.03 mg EAG/g of extract. Leaf extract obtained with soxhlet showed minimum inhibitory concentration (MIC) of 15.62 µg/mL, while stem extract obtained by maceration was able to inhibit the growth of E. faecalis at 62.5 µg/mL. Stem bark extracts showed a MIC of 500 µg/mL for both extraction methods, while no inhibition was observed for fruit extracts. CONCLUSION: In general, total phenolic content, antioxidant and antibacterial activities were higher in samples obtained by soxhlet. Our results provide important clues in order to identify alternative sources of bioactive compounds that can be used to develop new drugs.

Association Between Exercise and Treatment with Liraglutide in Obese Rats by Cafeteria Diet

Abstract The objective of this study was to evaluate the effect of liraglutide, an analog of glucagon-like peptide-1 (GLP-1) in association with physical exercise, on the metabolic and biochemical parameters of rats induced to obesity with a cafeteria diet. Male Wistar rats, aged 21 days, were randomly divided into: Controls (CON) receiving standard feed and water ad libitum; and obese (OBESE) receiving cafeteria diet ad libitum, added to the standard diet. Groups were then subdivided into: Liraglutide animals that received subcutaneous injections of liraglutide from 80 to 90 days of life; exercised (EXE) animals submitted to swimming sessions, three days a week (15 min); and liraglutide + EXE animals that received liraglutide in association with physical exercise. Treatment with liraglutide reduced deposits of mesenteric and periepididymal fat, HOMA-IR, triglycerides, glucose and insulin in obese group. It is important to note that the association of the two treatments reduced the body weight in animals, deposits of mesenteric and periepididymal fat, HOMA-IR, blood triglyceride levels, glucose and insulin in obese rats. As such, the association of liraglutide with exercise potentiated the effects of the drug and ameliorated obesity pathology more effectively. retirar

Desenvolvimento de métodos analíticos rápidos e de baixo custo para o controle de qualidade de medicamentos antidiabéticos utilizados no Brasil pelo Sistema Único de Saúde / Development of rapid and low cost analytical methods for the quality control of antidiabetic medications used in Brazil in the Unified Health System

O Diabetes Mellitus (DM) configura-se como uma epidemia mundial, traduzindo-se em um grave desafio para o sistema de saúde pública. Uma das medidas para a manutenção do nível glicêmico normal e redução da morbimortalidade decorrentes do DM consiste no uso de medicamentos antidiabéticos, como a glibenclamida (GLB) e a gliclazida (GLZ). Este trabalho objetivou o desenvolvimento de métodos analíticos inéditos, simples, rápidos, confiáveis e de baixo custo para a determinação espectrofotométrica do teor de GLB e de GLZ em formulações farmacêuticas. Testes qualitativos foram realizados a partir da reação da GLB e da GLZ com a Eosina (EOS). Observou-se a formação de compostos coloridos, opticamente estáveis com absorção máxima em 545 e 543 nm, respectivamente. Sob as condições experimentais otimizadas, curvas analíticas foram obtidas relacionando-se as concentrações de GLB e de GLZ com as absorbâncias equivalentes, contra os brancos de reagentes correspondentes. Os métodos propostos baseiam-se na formação de complexos binários, coloridos e altamente estáveis entre os fármacos investigados e a EOS. Quando aplicados para o doseamento de GLB e de GLZ contidas em amostras comerciais, os resultados obtidos mostraram que não houve diferenças significativas entre os métodos propostos e os métodos oficiais. A realização deste trabalho foi de suma importância, pois permitiu o desenvolvimento de métodos analíticos inéditos, precisos, exatos, confiáveis mais simples, rápidos, versáteis e com maior viabilidade econômica (baixo custo). Estes métodos apresentam potencial para utilização em análises de rotina para o controle de qualidade de fármacos antidiabéticos (GLB e GLZ) presentes em medicamentos consumidos no Brasil.

Diabetes Mellitus (DM) is a global epidemic, which represents a serious challenge for the public health system. One of the measures to maintain the normal glycemic level and reduce morbidity and mortality due to DM is the use of antidiabetic medicines such as glibenclamide (GLB) and gliclazide (GLZ). This work aimed at the development of unpublished, simple, fast, reliable and low cost analytical methods for the spectrophotometric determination of GLB and GLZ content in pharmaceutical formulations. Qualitative tests were performed from GLB and GLZ with Eosin (EOS). The formation of optically stable colored compounds with maximum absorption at 545 and 543 nm, respectively, was observed. Under optimized experimental conditions, analytical curves were obtained by relating the GLB and GLZ concentrations to the equivalent absorbances against the corresponding reagent blank. The proposed methods are based on the formation of binary, colored and highly stable complexes between investigated drugs and EOS. When applied to the GLB and GLZ assay contained in commercial samples, the results showed that there were no significant differences between the proposed methods and the official methods. The accomplishment of this work was of paramount importance, since it allowed the development of unpublished, precise, accurate, reliable, simpler, faster, more versatile analytical methods with greater economic feasibility (low cost). These methods can be used in routine analyzes for the quality control of antidiabetic drugs (GLB and GLZ) present in medicines consumed in Brazil.

Evaluation of the effects of S-methylisothiourea hemisulfate, an inducible nitric oxide synthase inhibitor, on the healing of colonic anastomosis in rats.

PURPOSE: To evaluate the effects of S-methylisothiourea hemisulfate (SMT) on the healing of colonic anastomosis in rats. METHODS: Sixty rats Wistar were distributed into two groups of 30 animals: experimental (E) and control C). The animals of experimental group received intraperitoneal SMT at 50 mg/kg/dose every 12 hours for 72 hours. The control group received intraperitoneal saline at the same volume of SMT. The rats were subdivided into subgroups groups of 10 for euthanasia on the third, seventh, and 14th postoperative days (POD). We evaluated clinical and weight evolution, breaking strength and histopathology; also, a blood sample was collected for serum dosage of nitrite/nitrate. RESULTS: There was more vascular neoformation (p=0.006) and granulation (p=0.002) in the E3 group, and more mononuclear infiltrates in the C3 group (p=0.041). There was also more edema in the C14 group (p=0.008). There was no statistically significant difference in breaking strength, nitrite/nitrate dosage, and the remaining histopathological parameters. CONCLUSION: The use of S-methylisothiourea hemisulfate improved the healing of colonic anastomosis in rats on the third postoperative day by accelerating the proliferative stage of healing, but without interfering with the breaking strength of the anastomosis.

Development and application of a portable instrument for drugs analysis in pharmaceutical preparations

This article describes the application and performance of an inexpensive, simple and portable device for colorimetric quantitative determination of drugs in pharmaceutical preparations. The sensor is a light detector resistor (LDR) incorporated into a black PTFE cell and coupled to a low-cost multimeter (Ohmmeter). Quantitative studies were performed with captopril/p-chloranil/H2O2 and methyldopa/ammonium molybdate systems. Calibration curves were obtained by plotting the electrical resistance of the LDR against the concentration of the colored species in the ranges 1.84 × 10-4 to 1.29 × 10-3mol L-1 and 5.04 × 10-4 to 2.52 × 10-3 mol L-1 for captopril/p-chloranil/H2O2 and methyldopa/ammonium molybdate systems, respectively, exhibiting good coefficients of determination. Statistical analysis of the results obtained showed no significant difference between the proposed methodologies and the official reported methods, as evidenced by the t-test and variance ratio at a 95% confidence level. The results of this study demonstrate the applicability of the instrument for simple, accurate, precise, fast,in situ and low-cost colorimetric analysis of drugs in pharmaceutical products.

Este artigo descreve o desenvolvimento e a aplicação de um dispositivo portátil, simples e barato para a determinação colorimétrica quantitativa de fármacos em formulações farmacêuticas. O sensor é um resistor detector de luz (RDL) colocado numa célula de PTFE e acoplado a um multímetro de baixo custo. Os estudos quantitativos foram realizados utilizando captopril/p-cloranil/H2O2 e metildopa/molibdato de amônio como sistemas reacionais. As curvas de calibração foram obtidas através da representação gráfica da resistência elétrica do RDL contra a concentração dos complexos coloridos formados nas faixas de 1,84 × 10-4 e 1,29 × 10-3 mol L-1 e 5,04 × 10-4 e 2,52 × 10- 3 mol L-1 para captopril/p-cloranil/H2O2 e de metildopa/molibdato de amônio, respectivamente, com bons coeficientes de determinação. As análises estatísticas dos resultados obtidos mostraram que não houve diferença significativa entre os métodos propostos e os métodos oficiais como evidente a partir dos testes "t-Student" eF-Fisher, com nível de confiança de 95%. Os resultados deste estudo demonstram que o instrumento proposto neste trabalho é simples, de fácil operação, baixo custo e apresentou boa exatidão e boa precisão para o doseamento de fármacos em medicamentos.

Development and validation of a simple spectrophotometric method for the determination of methyldopa in both bulk and marketed dosage formulations

A simple, precise, sensitive, rapid, specific and economical spectrophotometric method was developed to determine methyldopa (MTD) content in bulk and pharmaceutical dosage formulations. The proposed method was based on the formation of a colored product from the nitrosation reaction of MTD with sodium nitrite in an acid medium. The resultant nitroso derivative species reacts further with sodium hydroxide and is converted it into a more stable compound. This yellow nitrosation product exhibited an absorption maximum at 430 nm. Beer's Law was obeyed in a concentration range of 6.37 to 82.81 μg mL-1 MTD with an excellent coefficient of determination (R 2 = 0.9998). No interference was observed from common excipients in formulations. The results showed the method to be simple, accurate and readily applied for the determination of MTD in pure form and in pharmaceutical preparations. The analytical results obtained for these products using the proposed method are in agreement with those of the Brazilian Pharmacopoeia procedure at a 95% confidence level.

Desenvolveu-se método espectrofotométrico simples, preciso, sensível, rápido, específico e econômico para a determinação do teor de metildopa (MTD) em matéria-prima e em formulações farmacêuticas. O método proposto baseia-se na formação de um produto colorido resultante da reação de nitrosação da MTD com nitrito de sódio em meio ácido. A espécie resultante (nitroso derivado) reage com hidróxido de sódio e é convertida a um composto mais estável de cor amarela. Este produto exibiu máximo de absorção a 430 nm. A lei de Beer foi obedecida na faixa de concentração de 6,37 a 82,81 μg mL-1 de MTD com excelente coeficiente de determinação (R 2 = 0,9998). Não se observou interferência de excipientes comumente encontrados em formulações farmacêuticas comerciais. Os resultados demonstraram que o método proposto apresenta simplicidade, excelentes precisão e exatidão e pode ser aplicado para a determinação de MTD na sua forma pura e em preparações farmacêuticas. Os resultados analíticos obtidos pelo método proposto estão de acordo com aqueles obtidos pelo método oficial descrito na Farmacopéia Brasileira, a um nível de confiança de 95%.