Rui Oliveira Macêdo

Thermal characterization of dried extract of medicinal plant by DSC and analytical techniques

The increased search for herbal products has generated an increasing interest in improving the quality control of dried extracts by pharmaceutical industry since these are raw materials of great importance by their quality and versatility. This work aimed at the application of various analytical techniques (thermal analysis, X-ray diffraction, scanning electron microscopy, and infrared Fourier transform spectroscopy) in the characterization of dried extracts of two plants from the Brazilian semiarid region with medicinal properties. The DSC curves for the dried extracts of Ximenia americana L. and Schinopsis brasiliensis Engl. showed that thermal processes occur between 33.50 and 118.58xa0°C and between 39.17 and 126.14xa0°C. The X-ray powder diffraction revealed high degree of amorphization, but the dried extract of X. americana L. showed some diffraction peaks of high intensity. The IR spectra showed high variety of metabolites in the extracts dried. Through this study it was possible to verify the feasibility of applying these techniques in the characterization of raw materials from medicinal plants for use in the herbal medicines production.

THERMAL STABILITY OF PREDNISONE DRUG AND TABLETS

TG and DSC data were used to determine the thermal parameters of prednisone drug and tablets. Two formulations of prednisone 20 mg were analysed in the form of tablets. The TG curves of prednisone drug and tablets A and B displayed six, eight and seven thermal decomposition processes, respectively. Analysis of the DSC data pointed to chemical interactions between prednisone drug and the excipients of tablets A and B, suggested by alterations in the melting temperature of prednisone. The analysis revealed that prednisone drug is more stable than tablets A and B.

Characterization of herbal medicine with different particle sizes using pyrolysis GC/MS, SEM, and thermal techniques

Analytical techniques have been used to characterize compounds from herbal medicine, its products and extracts. The objective of this study was to characterize a variety of particle sizes of Erythrina velutina Willd powder. The samples used in the study were named MUF01 (710xa0μm), MUF03 (180xa0μm) and MUF05 (75xa0μm). The techniques employed were scanning electron microscopy (SEM), thermal analysis such as thermogravimetry (TG) and differential thermal analysis (DTA) together with pyrolysis coupled to gas chromatography/mass spectrometry (Pyr-GC/MS). SEM enabled us to detect the existence of divergences from the expected results from the granulometry process. Thermal analytical techniques (TG and DTA) showed the thermal decomposition profile, corresponding to physical and chemical phenomena. The chromatographic data relative to the peak area of the compounds analyzed evidenced quantitative differences in the chemical compositions of the samples MUF01, MUF03, and MUF05 at 300, 450 and 600xa0°C. Neophytadiene 2,6,10-trimethyl, 14 and 3-eicosyne were identified by Pyr-GC/MS at 300, 450 and 600xa0°C, and it classified the samples according the peak area values, which were MUF05xa0>xa0MUF03xa0>xa0MUF01. SEM, DTA and TG confirmed this through particle size uniformity, heat flow, and mass loss, respectively.

Correlation of thermal analysis and pyrolysis coupled to GC-MS in the characterization of tacrolimus

In recent years, thermal analysis has assumed major role in the pharmaceutical industry because it can be used to evaluate the stability both in the control of raw materials and the finished product, having employment potential in the development and characterization of new products and assessment processes. Tacrolimus (TCR) is a macrolide lactone with potent immunosuppressive activity. The purpose of this study was to characterize tacrolimus raw material using Thermal analysis and Pyrolysis coupled to Gas chromatography-Mass spectrometry (Pyr-GC-MS). It was analyzed four samples of tacrolimus named TCR A, B, C and D. Thermal analysis experiments was performed in Shimadzu equipment, under nitrogen and synthetic air atmosphere in different heating rate. Pyrolysis analysis was conducted in isothermal conditions of 300°C and 400°C coupled to GC-MS, in which the mass spectrometer was operated in scan mode to detect ions in the range of mass of m/z 25-900. The thermal studies by DSC, DTA and DSC-Photovisual showed desolvation process for all tacrolimus raw materials and TG-dynamical demonstrated two pseudo-polymorphic forms (monohydrate and sesquihydrate) of tacrolimus. It was observed good correlation between the stoichiometric mass losses of the TG-dynamical and identification of product ion in Pyr-GC/MS technique. It was possible to correlate the five pyrolytic product ions with the Ozawa kinetic analysis from the thermal decomposition of TG-dynamical. The thermal studies (DSC, DSC-Photovisual, DTA and TG-dynamical) were applied in the thermal characterization of the raw materials of tacrolimus which showed pseudo-polymorphic forms, which must be monitored by pharmaceutical industry, avoiding future problems in pharmaceutical process, chemical stability and bioavailability of the tacrolimus product.

Evaluation of compatibility between dried extracts of Myracrodruon urundeuva Allemão and pharmaceutical excipients by TG and DTA

Thermoanalytical techniques have been applied in studies of herbal products. Myracrodruon urundeuva Allemão (Anacardiaceae) is a native of Brazil with medicinal properties. This study aimed to characterize the dry extracts of M. urundeuva Allemão and to assess the compatibility of extracts with pharmaceutical excipients in physical mixtures using thermogravimetry (TG) and differential thermal analysis (DTA). The TG curve of M. urundeuva dry extract (ES) showed the occurrence of four mass loss events. The most significant mass loss of extract was observed between 193.5 and 267.0xa0°C with a loss of 29.7%. The DTA curve showed the endothermic nature of this event with a peak at 235.8xa0°C (ΔHxa0=xa0568.5xa0Jxa0g−1). This event is associated with the thermal decomposition of carbohydrates and other organic compounds present in the plant. The SEM image showed the particles of dry extract with spherical shapes, irregular sizes and rough surfaces. SEM analysis of physical mixtures showed that extract dry particles maintained their spherical morphology and appeared uniformly dispersed in the excipient particles. The TG and DTA curves showed no thermal incompatibility between the ES and the excipients lactose, cellulose and starch, but indicated a possible interaction with maltodextrin.

Sideroxylon obtusifolium herbal medicine characterization using pyrolysis GC/MS, SEM and different thermoanalytical techniques

This study aimed to characterize by analytical techniques Sideroxylon obtusifolium herbal medicine raw material derived from the leaves in different particle sizes, using scanning electron microscopy (SEM), thermoanalytical techniques [thermogravimetry (TG) and analysis differential thermal (DTA)] and pyrolysis coupled to gas chromatography/mass spectrometry (PYR-GC/MS). The different particle surface area among the samples was differentiated by the techniques. SEM distinguished the particles by its volumetric size, DTA and TG by the thermal and kinetic parameters and the PYR-GC/MS by degradation products chromatographic identification through the pyrograms.

Herbal medicine physical quality evaluation by thermal analysis using adapted Ozawa method

AbstractnThe aim of this study was to evaluate the physical quality of Tabebuia caraiba (Mart.) Bur. powder, separately in three batches of different particle sizes, through the adapted Ozawa method. The Ozawa model was used for thermogravimetry (TG) data analysis in dynamic synthetic air and nitrogen atmospheres in different heating rates (5, 10, 20 and 40xa0°C min−1). The software TA-50 was used to data treatment. Kinetic data showed different values of activation energy and same reaction order according to the particle powder sample size in a specific model (derivative or tangent) of data treatment. The difference factor (F1) was used to compare the parallelism line of the samples constructed by Ozawa graphs. Different kinetic results discriminate the particles size of the samples. TG technique allowed discriminating different particle sizes of herbal medicine powder.

Physical and chemical characteristics of Maytenus rigida in different particle sizes using SEM/EDS, TG/DTA and pyrolysis GC–MS

Thermoanalytical techniques have been widely applied in the characterization of herbal medicines, providing data about the herbal products quality. The objective of this work was to use analytical techniques for the Maytenus rigida powder in different particle sizes characterization. The techniques used were scanning electron microscopy (SEM) with energy-dispersive spectroscopy, differential thermal analysis (DTA), Thermogravimetry (TG), using the model of Ozawa to evaluate the kinetic parameters and gas chromatography coupled to pyrolysis/mass spectrometry (PYR-GC/MS). Different particle morphologies and size were verified by SEM. The thermoanalytical techniques (TG and DTA) showed physical and chemical processes occurred. Different degradation profiles curves were obtained when the samples were exposed to the atmosphere of nitrogen and synthetic air. Kinetic data showed different activation energy values and the same reaction order to the studied samples. Through Ozawa kinetic parameters, it was possible to observe granulometries distinctions to the herbal medicine powder batches. Pyrolysis allowed to correlate TG decomposition data with the identification of its degradation products and showed two similar compounds among the samples at lower temperatures (250xa0°C) and at higher temperatures (600xa0°C). The fingerprint of the degradation components by PYR-GC–MS and the other analytical tools has been utilized as an alternative to the quality control of herbal medicine evaluation. Ea obtained by dynamic TG in air synthetic atmosphere was the parameter which better differentiate the samples.

Thermal analysis study of solid dispersions hydrochlorothiazide

Solid dispersions (SD) are used as a technological strategy to increase the aqueous dissolution rate of poorly soluble active pharmaceutical ingredients, such as hydrochlorothiazide (HCTZ), an antihypertensive used frequently in medical clinics. The aim of this study was to characterize solid dispersions of HCTZ obtained with different processing adjuvants, using the DSC, TG, XRPD, FTIR and SEM techniques, and to evaluate the influence of carriers used in biopharmaceutical performance by analyzing dissolution efficiency. The SDs were obtained using the solvent method, and spray drying was used as the drying technique. The carriers used PEG 1500, sodium lauryl sulfate and PVP K30. The calorimetric analysis and XRPD showed amorphous behavior to SDs that used hydrophilic polymer as a carrier, and thermogravimetric analysis showed maintaining thermal stability of the HCTZ for most dispersions. FTIR detected intermolecular interactions of hydrogen bonds, while SEM showed the formation of microparticles with a tendency to sphericity. Acquired morphology associated with amorphization contributed to the increase in dissolution efficiency of dispersions, being that this SD (HCTZ/PVP K30) showed the best increase in dissolution. We therefore concluded that the analytical techniques used were of fundamental importance to the characterization of pharmaceutical products developed as to their physicochemical properties and the prescience of the oral bioavailability of HCTZ.

Thermal decomposition profile of chitosan microparticles produced with Schinopsis brasiliensis Engler extract

Schinopsis brasiliensis Engler is a plant of Anacardiaceae family, used in the treatment of various diseases. Dried extracts have been used as intermediate product to obtain different pharmaceutical forms. Microparticles are a controlled-release system that protects unstable materials, and assist in increasing bioavailability parameters, while still allowing release to the specific site. This study aimed to trace the profile of microparticles of thermal degradation produced with S. brasiliensis Engl. extract in a chitosan matrix, evaluating some microparticles parameters (encapsulation efficiency, zeta potential, polydispersity index and SPAN factor). Thermal behavior of microparticles showed chitosan is able to protect the S. brasiliensis extract. Encapsulation efficiency and zeta potential are not directly proportional to flow rate, differently to polydispersity index and SPAN factor. This study showed the chitosan potential to protect S. brasiliensis extract of thermal degradation, allowing future applications.