Irinaldo Diniz Basílio Júnior

Short-term stability studies of ampicillin and cephalexin in aqueous solution and human plasma: Application of least squares method in Arrhenius equation

A limited number of studies with application of the Arrhenius equation have been reported to drugs and biopharmaceuticals in biological fluids at frozen temperatures. This paper describes stability studies of ampicillin and cephalexin in aqueous solution and human plasma applying the Arrhenius law for determination of adequate temperature and time of storage of these drugs using appropriate statistical analysis. Stability studies of the beta-lactams in human plasma were conducted at temperatures of 20°C, 2°C, -20°C and also during four cycles of freeze-thawing. Chromatographic separation was achieved using a Shimpak C(18) column, acetonitrile as organic modifier and detection at 215nm. LC-UV-MS/MS was used to demonstrate the conversion of ampicillin into two diastereomeric forms of ampicilloic acid. Stability studies demonstrated degradation greater than 10% for ampicillin in human plasma at 20°C, 2°C and -20°C after 15h, 2.7days, 11days and for cephalexin at the same temperatures after 14h, 3.4days and 19days, respectively, and after the fourth cycle of freezing-thawing. The Arrhenius plot showed good prediction for the ideal temperature and time of storage for ampicillin (52days) and cephalexin (151days) at a temperature of -40°C, but statistical analysis (least squares method) must be applied to avoid incorrect extrapolations and estimated values out uncertainty limits.

Development and Validation of Analytical Methodology and Evaluation of the Impact of Culture Conditions and Collection Associated with the Seasonality in the Production of Essential Oil of Plectranthus amboinicus (Lour) Spreng

The species of Plectranthus (Lamiaceae) are used in folk medicine in many parts of the world (Hedge, 1992). The genus occurs in four continents: Africa, America, Oceania and Asia and phytochemical studies reported that abietane diterpenes and triterpenoids are the most common metabolites in the genus (Albuquerque, 2000). The β-caryophyllene, a constituent of essential oil of Plectranthus amboinicus, according to Haslam (1996), can be used in traditional medicine as a remedy for the treatment of various organic illnesses. The caryophyllene showed the following properties: antiedemico (Shimizu, 1990), fagorrepelente (Keeler et al., 1991), antiinflammatory (Shimizu, 1990), antitumor (Zheng et al., 1992), bactericidal (Kang et al., 1992), insetifugo (Jacobson et al., 1990) and spasmolytic (Duke, 1992). Some of these activities have been given to its oxide derivative (Shimizu, 1990, Zheng et al., 1992). The registration of herbal medicines (Anvisa, 2004) establishes quality control of raw material is a prerequisite for obtaining essential herbal with reproducibility of action. The development of an analytical method, the adaptation method known or the implementation of the evaluation process involves estimating its efficiency in the laboratory routine. Particular method is considered valid if its characteristics are in accordance with the prerequisites established (Brito et al, 2003). Validation is essential to determine whether methods developed are completely suitable for their intended purposes, in order to obtain reliable results that can be satisfactorily interpreted. In this way, it allows the knowledge of the limitations and reliability of the measurements made in the analysis. The main objective

Estudo do processo de intercalação via solução PVP-bentonita: a avaliação da influência do tempo reacional, da proporção de polímero-argila e da massa molar média

In this paper were produced reactions by solution PVP-bentonite, natural and modified, where we studied the influence of reaction time (15, 30, 45 minutes, 1, 24, 48, 72 hours), polymer-clay ratio (2:1, 1:1, 1:2) and molar mass (PVP K-30, PVP K-90). Techniques such as XRD, FTIR and TGA were used to explain the formation of intercalated nanocomposites and their reaction process.

Phytochemical screening, antioxidant and antibacterial activities of some commercial extract of propolis

This study investigated the chemical composition, flavonoids, phenolic compounds, antioxidant activity and antibacterial activity of commercial propolis extracts produced in the Sergipe and Alagoas States of Brazil as potential bioproducts for the food and pharmaceutical industries. Four samples were analyzed, three brown propolis extracts and one red propolis extract, and were characterized through phytochemical screening, chemical, chromatographic profile and antibacterial activity. Phytochemical analysis detected the presence of triterpenoids and phenolic compound in propolis extracts. Propolis extracts showed total phenolic content between 9 and 15% and total flavonoids >2%. Propolis extracts showed excellent antioxidant activity with inhibition of the Free radical DPPH˙ between 97 and 60%, which confirm the results obtained in total phenolics, total flavonoids content and antibacterial activity. The chromatographic profile showed differences for brown propolis samples and quite different from the red propolis extract, which present flavonoids as isoflavonoids, pterocarpans, chalcones and guttiferones. Commercial propolis extract (propolis extract C and propolis extract D) showed excellent activity for Staphylococcus aureus ATCC 25923 and moderate activity for Pseudomonas aeruginosa ATCC 27853. The chemical characterization of propolis extracts is fundamental in the process of standardization and monitoring of the chemical composition susceptible to geographic and seasonal variation. These results point to new possibilities of use as bio-preservative of processed foods as well as in the development of pharmaceuticals and nutraceuticals products from propolis extract C and D in its formulation actuate on the inhibition of some pathogenic microorganisms strains.

Lipase Activity in the Larval Midgut of Rhynchophorus palmarum: Biochemical Characterization and the Effects of Reducing Agents

Lipases have key roles in insect lipid acquisition, storage, and mobilization and are also fundamental to many physiological processes in insects. Lipids are an important component of insect diets, where they are hydrolyzed in the midgut lumen, absorbed, and used for the synthesis of complex lipids. The South American palm weevil Rhynchophorus palmarum is one of the most important pests on commercial palm plantations. However, there are few studies about lipid digestion for this insect. In this work, we have described the biochemical characterization of the lipase activity in the posterior midgut of the R. palmarum palm weevil. Lipase activity was highest between the temperatures of 37 °C and 45 °C and at pH 6.5. Lipase activity was also sensitive to variations in salt and calcium concentrations. Lipases have been described structurally as enzymes with the Ser-His-Asp Catalytic Triad, containing an active serine. The serine protease inhibitor PMSF (phenylmethane sulfonyl fluoride) inhibited the lipases from R. palmarum, demonstrating the importance of a serine residue for this activity. The ability of the lipases to hydrolyze p-Nitrophenyl esters with different chain lengths has revealed the activities of a broad range of substrates. The lipase activities of R. palmarum increased in the presence of reduced glutathione (GSH) and dithiothreitol (DTT), while in the presence of oxidized glutathione (GSSG), activities were drastically reduced. To our knowledge, this study has provided the first information about lipase activity in the R. palmarum palm weevil.