Comparative study of two spectrophotometric reagents for catechol analysis in guarana seeds powder

In this article are described and compared two spectrophotometric methods for the analysis of catechol (o-hydroxyphenol) in Paullinea cupana var. sorbilis, popularly known as guarana. The pounded seed samples were extracted with ethanol 97% v/v and the solutions were treated with p-aminophenol in alkaline ethanolic medium or m-aminophenol and sodium metaperiodate in buffered aqueous solution (pH 3.0). The absorbance was measured at 586 nm and 520 nm respectively. Four different commercial products were analyzed and the results were compared with those obtained with the m-aminophenol method. Despite the good quality of the calibration curves, in the two methods the interference of the matrix was observed. This problem was settled using the standard addition method. Comparison between the results obtained by the two methods, using the statistical Student's t-test, showed that there is no significant difference at the 95% confidence level.14112913

Development and Evaluation of Praziquantel Solid Dispersions in Sodium Starch Glycolate

Purpose: To develop and characterize solid dispersions of praziquantel (PZQ) with sodium starch glycolate (SSG) for enhanced drug solubility.Methods: PZQ solid dispersion (SD) was prepared using co-precipitation method by solvent evaporation. The ratios of PZQ to SSG were 2:1, 1:1, 1:2, 1:3 (w/w). PZQ solubility was evaluated in purified water, and PZQ dissolution test was carried out in 0.1N HCl. Structural characterization of the dispersions was accomplished by x-ray diffraction (XRD) and infrared spe ctroscopy (FTIR) while the external morphology of the SDs, SSG and PZQ were studied by scanning electron microscopy (SEM). Mucoadhesion properties of the SD (1:3) and SSG, on mucin disks were examined using texture profile analysis.Results: The highest solubility was obtained with 1:3 solid dispersion, with PZQ solubility of 97.31 %, which is 3.65-fold greater than the solubility of pure PZQ and physical misture (PM, 1:3). XRD results indicate a reduction in PZQ crystallinity while infrared spectra showed that the functional groups of PZQ and SSG were preserved. SEM showed that the physical structure of PZQ was modified from crystalline to amorphous. The amount of PZQ in PM and SD (1:3) that dissolved in 60 min was 70 and 88 %, respectively, and these values increased to 76 and 96 %, respectively. The solid dispersion reduced the mucoadhesive property of the glycolate.Conclusion: Solid dispersion formulation using SSG is a good alternative approach for increasing the dissolution rate of PZQ.Keywords: Praziquantel, Drug bioavailability, Schistosomiasis, Solid dispersion, Co-precipitation, Sodium starch glycolat

In vitro evaluation of copaiba oil as a kojic acid skin enhancer

The capacity or copaiba oil to act as a skin penetration enhancer for the depigmenting agent kojic acid was evaluated using an in vitro diffusion system with static flux and shed rattlesnake skin membrane, Crotalus durissus terrificus, in saline solution at 34 +/- 2 degrees C as the fluid receptor. The quantities of kojic acid liberated into the fluid receptor were determined by spectrophotometry at 268 nin with intervals of one and a half hours. The membranes, pretreated with copaiba oil at 25% and 50% v/v, gave flux values of 8.0 and 12.7 mu g/cm(2)/h, permeability values of 2.0 and 3.3 cmx10(-4)/h, and promotion factors of 4.1 and 3.7, respectively. These results indicate that copaiba oil, at the two concentrations studied, has the capacity to promote penetration of kojic acid.46236337

Determination of salicylate in blood serum by flow injection with immobilized salicylate hydroxylase

A flow injection (FI) enzymatic system, based on the use of immobilized salicylate hydroxylase in glass beads, was developed for the determination of salicylate. Salicylate hydroxylase and nicotinamide adenine dinucleotide (NADH) are used to convert salicylate to catechol. The reaction of catechol with 4-aminophenol at high pH yields a colored product which is detected spectrophotometrically at 565 nm. Ten samples of human serum containing from 5.0 x 10(-4) to 5.0 x 10(-3) mol/L added salicylate were analyzed and the recovery was determined. Eight additional serum samples containing salicylate were analyzed by the Trinder test and the proposed method. The results obtained with the 2 methods showed good agreement by the statistical Student's t-test. The relative precision of the method is about 3.4% (RSD of the mean recovery). Considering the lowest concentration analyzed, the quantitative limit of detection is about 0.2 x 10(-5) mol/L (3 x SD). The volume of the sample used was 150 muL. The proposed method was also used to analyze medicines containing acetylsalicylic acid. The results were statistically compared with those obtained through the U.S. Pharmacopoeia procedure and showed excellent agreement.8451363136

Preparation of iron III aminocarboxylates from hydrolized corn cake from oil extraction. Chemical characterization and evaluation of iron bioavailability

Anemia caused by iron deficiency is the most prevalent nutritional disorder. The main causes are low iron ingestion and/or low bioavailability of the iron ingested. This project aimed at synthesizing an organic compound containing iron, by means of a reaction between Fe3+ ions and an acid hydrolyzed vegetable protein, with low NaCl content, obtained from a corn cake remaining after oil extraction. The product was prepared by the use of a 1: 1 molar relation between the total content of aminoacids and the iron ions. The chemical characterization was made using infrared spectroscopy and C, H, N and iron analyses. The iron analyses were carried out using atomic absorption and presented a value of 25.9%. The iron bioavailability was evaluated using the depletion and repletion method in anemic mice and evaluation using the Hemoglobin Regeneration Index. The compound exhibited 112.8% bioavailability with respect to ferrous sulphate.39478379

A simple device for quantitative colorimetric diffuse reflectance measurements

A very simple and low cost reflectometer, for colorimetric diffuse reflectance measurements is described. The proposed instrument uses a light dependent resistor (LDR), as a sensor, and a light emitter diode (LED), as light source. The performance of the device was compared with that of a commercial instrument, measuring the reflectance of the Pantone(R) Process Black Uncoated Palette. The quantitative analysis of nickel, in a catalyst, using dimethylglyoxime as colorimetric reagent, was also used to test the device. The observed precision was about 6% (R.S.D.). These results were compared with those obtained by the gravimetric method using the same reaction, through the statistical Student's t-test procedure. A complete agreement was observed. The good quality of all the obtained results allows the recommendation of the instrument for diffuse reflectance measurements including quantitative analytical procedures. (C) 2002 Elsevier Science B.V. All rights reserved.881606

Green spectrophotometric method for the quantitative analysis of vancomycin in pharmaceuticals and comparison with HPLC

A spectrophotometric method for the determination of vancomycin base, (VCM), and vancomycin hydrochloride, (HVCM), based on the reaction with copper (II) ions, is presented. The obtained detection limit is about 4.5 x 10(-5) mol L-1. The working analytical range falls between 1.0 x 10(-3) mol L-1 and 1.0 x 10(-2) mol L-1. Recovery studies in presence of excipients were performed. The recovery results were compared with HPLC. For HVCM the proposed method presented similar recovery to that of HPLC, 100.4% vs. 100.2%, but better precision, 1.9% vs. 6.1%. In the VCM case the recovery is quite better, 100.5% vs. 89.6%, with a little smaller precision, 2.1% vs. 1.3%.41582283

Rapid determination of nitrites in food using a diffuse UV-visible reflectance method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)A simple, low-cost, sensitive and selective method for the determination of trace quantities of nitrite in foods such as cheese and cured meat using diffuse ultraviolet-visible reflectance was developed. It is based on the reaction of nitrite with sulphadiazine and alpha-naphthol, which produces a coloured product in basic medium. The reaction is carried out directly in the measuring cell. For cheese the limit of detection (LOD), expressed as NaNO2, was estimated to be about 2.0 x 10(-2) mg l(-1) (2.9 x 10(-7) mol l(-1)) in the final measuring solution and 0.17 mg kg(-1) in cheese (2.5 x 10(-6) mol kg(-1)). The relative standard deviation (RSD) varied from 5% to 8% depending on the sample. For meat the LOD was estimated to be about 2.0 x 10(-2) mg l(-1) (2.9 x 10(-7) mol l(-1)) in the final measuring solution and 0.13 mg kg(-1) in meat (1.9 x 10(-6) mol kg(-1)). The RSD varied from 3% to 6% depending on the sample. The results of the proposed method were also compared with those obtained with the official method using the statistical Student's t-test and F-test procedures.29812561262TWASConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Preparation and Evaluation of Modified Release Zidovudine Tablets

Zidovudine is a drug used for the treatment of AIDS. The objective of this work was to prepare tablets for modified release of zidovudine. Hydroxypropyl methylcellulose HPMC K100LV and HPMC K4M at 1250 %, 18.75 % and 25.00 % were used. The tablets produced with 12.50 % of HPMC reached 100 % of the zidovudine release in 6 hours, while those produced with 18.75 and 25.00 %, released 24 h, following the Higuchi and First Order kinetic models, respectively. The calculated release exponent pointed out that formulations follow the anomalous type of release mechanism, with a combined phenomena of diffusion and erosion.3081512151