Maria Irene Yoshida

Federal University of Minas Gerais, Cidade de Minas, Minas Gerais, Brazil

Are you Maria Irene Yoshida?

Claim your profile

Publications (59)92.73 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: This work aimed to develop solid lipid nanoparticles (SLN) co-loaded with doxorubicin and α-tocopheryl succinate (TS), a succinic acid ester of α-tocopherol that exhibits anticancer actions, evaluating the influence of TS on drug encapsulation efficiency. The SLN were characterized for size, zeta potential, entrapment efficiency (EE), and drug release. Studies of in vitro anticancer activity were also conducted. The EE was significantly improved from 30 ± 1% to 96 ± 2% for SLN without and with TS at 0.4%, respectively. In contrast, a reduction in particle size from 298 ± 1 to 79 ± 1 nm was observed for SLN without and with TS respectively. The doxorubicin release data show that SLN provide a controlled drug release. The in vitro studies showed higher cytotoxicity for doxorubicin-TS-loaded SLN than for free doxorubicin in breast cancer cells. These findings suggest that TS-doxorubicin-loaded SLN is a promising alternative for the treatment of cancer.
    No preview · Article · Apr 2016 · Colloids and surfaces B: Biointerfaces
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Resumo Implantes poliméricos biodegradáveis para o tratamento do câncer, contendo Sirolimus (SRL), foram desenvolvidos utilizando o copolímero derivado dos ácidos lático e glicólico (PLGA 50:50 e 75:25), poliprolactona (PCL) e quitosana como matrizes poliméricas, à 25% p/p com o fármaco. Para o desenvolvimento das formulações farmacêuticas, os estudos por Termogravimetria (TG) e Calorimetria Exploratória Diferencial (DSC) demonstraram que os polímeros são compatíveis com o fármaco, no entanto o processo de elaboração dos implantes compromete a fusão do SRL, o que pode estar relacionado à degradação do fármaco ou alteração cristalina do SRL.
    Full-text · Conference Paper · Nov 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: abStract Despite the considerable environmental importance of mercury (hg), given its high toxicity and ability to contaminate large areas via atmospheric deposition, little is known about its activity in soils, especially tropical soils, in comparison with other heavy metals. this lack of information about hg arises because analytical methods for determination of hg are more laborious and expensive compared to methods for other heavy metals. the situation is even more precarious regarding speciation of hg in soils since sequential extraction methods are also inefficient for this metal. The aim of this paper is to present a technique of thermal desorption associated with atomic absorption spectrometry, TDAAS, as an efficient tool for quantitative determination of hg in soils. the method consists of the release of hg by heating, followed by its quantification by atomic absorption spectrometry. It was developed by constructing calibration curves in different soil samples based on increasing volumes of standard hg 2+ solutions. Performance, accuracy, precision, and quantification and detection limit parameters were evaluated. No matrix interference was detected. Certified reference samples and comparison with a Direct Mercury analyzer, DMa (another highly recognized technique), were used in validation of the method, which proved to be accurate and precise.
    Full-text · Article · Sep 2015 · Revista Brasileira de Ciência do Solo
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Topical therapy is the first choice for the treatment of mild to moderate acne and all-trans retinoic acid is one of the most used drugs. The combination of retinoids and antimicrobials is an innovative approach for acne therapy. Recently, lauric acid, a saturated fatty acid, has shown strong antimicrobial activity against Propionibacterium acnes. However, topical application of retinoic acid is followed by high incidence of side-effects, including erythema and irritation. Solid lipid nanoparticles represent an alternative to overcome these side-effects. This work aims to develop solid lipid nanoparticles loaded with retinoic acid and lauric acid and evaluate their antibacterial activity. The influence of lipophilic stearylamine on the characteristics of solid lipid nanoparticles was investigated. Solid lipid nanoparticles were characterized for size, zeta potential, encapsulation efficiency, differential scanning calorimetry and X-ray diffraction. The in vitro inhibitory activity of retinoic acidlauric acid-loaded solid lipid nanoparticles was evaluated against Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. High encapsulation efficiency was obtained at initial time (94±7% and 100±4% for retinoic acid and lauric acid, respectively) and it was demonstrated that lauric acid-loaded-solid lipid nanoparticles provided the incorporation of retinoic acid. However, the presence of stearylamine is necessary to ensure stability of encapsulation. Moreover, retinoic acid-lauric acid-loaded solid lipid nanoparticles showed growth inhibitory activity against Staphylococcus epidermidis, Propionibacterium acnes and Staphylococcus aureus, representing an interesting alternative for the topical therapy of acne vulgaris.
    Full-text · Article · Sep 2015 · Journal of Nanoscience and Nanotechnology
  • Source

    Full-text · Conference Paper · Aug 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Three copper(II) complexes, [Cu2(O2CC4H3O)4(H2O)2]·H2O (1), {[Cu2(O2CC4H3O)4(bipy)2(H2O)2]·2H2O}n(2), and {[Cu(bpp)2(H2O)](O2CC4H3O)2·7H2O} (3) [O2CC4H3O = 2-furanocarboxylate anion, bipy = 4, 4′-bipyridine, and bpp = 1, 3-bis(4-pyridyl)propane] were synthesized and their crystal and molecular structures were determined by single-crystal X-ray diffraction analysis. Compound 1 consists on bimetallic tetracarboxylate units exhibiting a common paddle wheel structure. The paddle wheel units are connected by hydrogen bonding along the crystallographic b axis and π–π stacking interactions between the furano rings along the crystallographic c axis, giving rise to a 2D supramolecular array. Compounds 2 and 3 were made up in the presence of 4, 4′-bipyridine and 1, 3-bis(4-pyridyl)propane ligands, respectively, to produce 1D polymeric chains by metal-ligand interactions. The presence of other weak non-covalent interactions in these compounds extends the systems dimensionality to form 3D supramolecular networks.
    No preview · Article · Aug 2015 · Zeitschrift für anorganische Chemie
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to develop and evaluate the effects of chitosan inserts for sustained release of the angiotensin-converting enzyme 2 (ACE2) activator, diminazene aceturate (DIZE), in experimental glaucoma. Monolayer DIZE loaded inserts (D+I) were prepared and characterized through swelling, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC) and in vitro drug release. Functionally, the effects of D+I were tested in glaucomatous rats. Glaucoma was induced by weekly injections of hyaluronic acid (HA) into the anterior chamber and intraocular pressure (IOP) measurements were performed. Retinal ganglion cells (RGC) and optic nerve head cupping were evaluated in histological sections. Biodistribution of the drug was accessed by scintigraphic images and ex vivo radiation counting. We found that DIZE increased the swelling index of the inserts. Also, it was molecularly dispersed and interspersed in the polymeric matrix as a freebase. DIZE did not lose its chemical integrity and activity when loaded in the inserts. The functional evaluation demonstrated that D+I decreased the IOP and maintained the IOP lowered for up to one month (last week: 11.0± 0.7 mmHg). This effect of D+I prevented the loss of RGC and degeneration of the optic nerve. No toxic effects in the eyes related to application of the inserts were observed. Moreover, biodistribution studies showed that D+I prolonged the retention of DIZE in the corneal site. We concluded that D+I provided sustained DIZE delivery in vivo, thereby evidencing the potential application of polymeric-based DIZE inserts for glaucoma management.
    Full-text · Article · Jul 2015 · PLoS ONE
  • Source

    Full-text · Conference Paper · Jun 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: reSuMo a correlação entre as características físicas e químicas do solo e o teor de mercúrio natural é importante para identificar aquelas que mais influenciam na retenção desse elemento nesses solos e sua distribuição nos diversos compartimentos ambientais. esse estudo teve por objetivos determinar o teor de Hg de solos sem influência antropogênica e correlacionar esse teor com as características físicas e químicas dos solos. a relevância deste trabalho se deve ao fato que a maioria das pesquisas é focada em solos contaminados e, em caso de solos tropicais, as pesquisas são ainda mais escassas. as características físicas e químicas de diferentes solos de mata natural do estado de Minas gerias e de um solo do estado do rio de Janeiro foram correlacionadas com os teores naturais de Hg dos solos. o teor de Hg foi determinado empregando-se o analisador direto de Hg dMa-80. a faixa de concentração de Hg encontrada foi de 0 a 215 µg kg-1 com média de 81 µg kg-1. o teor de Hg dos solos correlacionou-se principalmente com o teor de argila e o pH do solo. Não houve correlação entre o teor de Hg e o de c. para solos com teores mais altos de Hg e mesma textura, a capacidade de troca catiônica passa a ser uma variável importante. palavras-chave: metal pesado, solos tropicais, pH, textura.
    Full-text · Article · Jun 2015 · Revista Brasileira de Ciência do Solo
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The role of chemical and mineralogical soil properties in the retention and oxidation of atmospheric mercury in tropical soils is discussed based on thermal desorption analysis. The retention of gaseous mercury by tropical soils varied greatly both quantitatively and qualitatively with soil type. The average natural mercury content of soils was 0.08±0.06μgg(-1) with a maximum of 0.215±0.009μgg(-1). After gaseous Hg(0) incubation experiments, mercury content of investigated soils ranged from 0.6±0.2 to 735±23μgg(-1), with a mean value of 44±146μgg(-1). Comparatively, A horizon of almost all soil types adsorbed more mercury than B horizon from the same soil, which demonstrates the key role of organic matter in mercury adsorption. In addition to organic matter, pH and CEC also appear to be important soil characteristics for the adsorption of mercury. All thermograms showed Hg(2+) peaks, which were predominant in most of them, indicating that elemental mercury oxidized in tropical soils. After four months of incubation, the thermograms showed oxidation levels from 70% to 100%. As none of the samples presented only the Hg(0) peak, and the soils retained varying amounts of mercury despite exposure under the same incubation conditions, it became clear that oxidation occurred on soil surface. Organic matter seemed to play a key role in mercury oxidation through complexation/stabilization of the oxidized forms. The lower percentages of available mercury (extracted with KNO3) in A horizons when compared to B horizons support this idea. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · May 2015 · Chemosphere
  • Source

    Full-text · Dataset · Mar 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the present study were evaluated the compatibility of ciprofibrate (CIP) with pharmaceutical excipients usually used in the solid forms by analytical techniques. Binary mixtures with pharmaceutical excipients were examined by Differential Screening Calorimetry (DSC) initially used to assess compatibility of mixtures of CIP and each selected excipients in a 1:1 (w/w) physical mixtures. The Fourier Transform Infrared (FTIR) spectroscopy and X-ray Powder Diffractometry were used to provide a complete investigation of the binary mixtures. The CIP:hydroxypropylmethylcellulose mixture displayed some physical interaction based on the DSC results, but the FTIR study ruled out any chemical change. The binary mixture with microcrystalline cellulose showed changes in the XRDP. Keywords: Ciprofibrate. Drug-excipient interaction. Thermal analysis. FTIR. XRPD.
    Full-text · Conference Paper · Nov 2014
  • Source

    Full-text · Dataset · Oct 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this study, the physical and thermal properties of essential oil microparticles of oregano (Origanum vulgare L.) dried via spray drying were examined. The product was characterized by morphology, mean diameter, particle size distribution, moisture sorption curve, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The process promoted the formation of spherical capsules with high polydispersity. The isotherm exhibited type II behavior (sigmoidal curve), and the best fit was obtained by the Guggenheim–Anderson–de Boer (GAB) model (E = 6.748%). The DSC analysis showed that the increase equilibrium moisture content reduced the Tg value of the microparticles (164.47–91.29C). The samples stored at low humidity resulted in more thermally stable particles, and the samples with equilibrium moisture content of 4.74% showed higher thermal stability.Practical ApplicationsThe applications of essential oils with relevant antioxidant activities, such as oregano essential oil, as a food additive is limited in the conventional form, due to their fast degradation triggered by temperature, light, presence of oxygen and humidity, among others. The encapsulation technique by spray drying has been successfully used to overcome this drawback. However, the spray-dried products may present some technological problems, such as high hygroscopicity and low resistance when subjected to high temperatures. The evaluation of microparticle stability is a relevant and important issue when desiring to ensure their quality and application. Studies of the functional properties such as hygroscopicity, sorption behavior and thermal resistance determine the ideal conditions for the storage of this type of product.
    Full-text · Article · Oct 2014 · Journal of Food Process Engineering
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hydrochlorothiazide is a diuretic used to treat hypertension that belongs to class IV of the Biopharmaceutics Classification System. The drug was evaluated by quality control, thermal characterization tests, and pharmaceutical formulation compatibility studies. It was concluded that the generic drug, Lab 2, was not a pharmaceutical equivalent. The compounded drugs, Lab 5 and Lab 6, produced unsatisfactory but expected results, since there is no requirement for dissolution and dissolution profile testing for the commercialization of these products. In a compatibility study, lactose and mannitol were shown to be incompatible with HCTZ, which may explain the lack of equivalence of the generic pharmaceutical product, associated with other situations.
    Preview · Article · Oct 2014 · Molecules
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study was conducted to evaluate the effects of the partial substitution of whey protein isolate (WPI) by inulin (IN) or maltodextrin (MD) as wall materials on the characteristics of microparticles containing fish produced by spray drying. Three treatments, WPI, WPI/MD (1:1) and WPI/IN (1:1), were evaluated in a completely randomised design with three replicates. The solubility and hygroscopicity of the particles were not affected by the wall material, attaining average values of 79% and 5.5 g.100g- 1, respectively. The partial substitution of WPI by inulin improved the wettability properties of the powders and reduced the occurrence of surface oil on the particles. The surface oil content was 5.6%, 6.5% and 7.7% for the particles produced using WPI/IN, WPI/MD and WPI, respectively. The particles presented smoother surfaces, with a smaller number of folds, when inulin was present. The GAB model was chosen as the model best adjusted to the isotherms, with values of moisture content on the monolayer (Xm) equal to 0.036 g.g- 1, 0.026 g.g- 1 and 0.074 g.g- 1 for the WPI, WPI/MD and WPI/IN microparticles, respectively. All of the powders obtained from these treatments exhibited a no crystalline structure, and the glass transition temperatures of these anhydrous powders were 168 °C, 149 °C and 131 °C for the WPI, WPI/MD and WPI/IN microparticles, respectively. The use of inulin and maltodextrin proved to be good alternatives secondary wall materials for fish oil together with WPI.
    Full-text · Article · Aug 2014 · Food Research International
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of the present study was to develop and assess a novel sustained-release drug delivery system of Bimatoprost (BIM). Chitosan polymeric inserts were prepared using the solvent casting method and characterized by swelling studies, infrared spectroscopy, differential scanning calorimetry, drug content, scanning electron microscopy and in vitro drug release. Biodistribution of 99mTc-BIM eye drops and 99mTc-BIM-loaded inserts, after ocular administration in Wistar rats, was accessed by ex vivo radiation counting. The inserts were evaluated for their therapeutic efficacy in glaucomatous Wistar rats. Glaucoma was induced by weekly intracameral injection of hyaluronic acid. BIM-loaded inserts (equivalent to 9.0 µg BIM) were administered once into conjunctival sac, after ocular hypertension confirmation. BIM eye drop was topically instilled in a second group of glaucomatous rats for 15 days days, while placebo inserts were administered once in a third group. An untreated glaucomatous group was used as control. Intraocular pressure (IOP) was monitored for four consecutive weeks after treatment began. At the end of the experiment, retinal ganglion cells and optic nerve head cupping were evaluated in the histological eye sections. Characterization results revealed that the drug physically interacted, but did not chemically react with the polymeric matrix. Inserts sustainedly released BIM in vitro during 8 hours. Biodistribution studies showed that the amount of 99mTc-BIM that remained in the eye was significantly lower after eye drop instillation than after chitosan insert implantation. BIM-loaded inserts lowered IOP for 4 weeks, after one application, while IOP values remained significantly high for the placebo and untreated groups. Eye drops were only effective during the daily treatment period. IOP results were reflected in RGC counting and optic nerve head cupping damage. BIM-loaded inserts provided sustained release of BIM and seem to be a promising system for glaucoma management.
    Full-text · Article · Apr 2014 · PLoS ONE
  • [Show abstract] [Hide abstract]
    ABSTRACT: Viscoelastic polyurethane (PU) foams based on modified tung oil, ethylene glycol and polymeric MDI, and reinforced with rice husk ash (RHA), were prepared by a free-rise pouring method and characterized in terms of density, compression and dynamic mechanical behavior. The density of foams ranged between 50 and 90 kg/m3, depending on the position of the sample with respect to the foam rise direction and filler content. As revealed by dynamic mechanical tests, the foams exhibited two different and broad thermal transitions, the temperature of their maxima depending on filler concentration. Compression modulus, compressive strength and storage modulus increase as foam density increases but decreases as rice husk ash concentration increases due to the detrimental changes induced by the filler in the foam cellular structure. However, densification strain exhibits the opposite behavior, indicating that reinforced foams can sustain slightly higher deformations without collapsing, probably due to a reduced reactivity of the components induced by the filler.
    No preview · Article · Jun 2013 · Polymer Testing
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Co{[14HBDC][14BDC]0,5[INH]} (1) coordination polymer was synthesised by a solvothermal route using the ligands 1,4-benzenedicarboxylic acid [14BDC], isonicotinylhydrazine [INH] and Co(NO3)·6H2O. It was characterised by elemental analysis (CHN), infrared vibrational spectroscopy, thermal analysis (TGA, DrTGA and DSC) and single-crystal X-ray diffraction analysis. In this coordination polymer, the ligand INH is coordinated to the metal site in two ways, acting as a bridging ligand. Unlike INH, 14BDC acts as a bridging ligand between two metal sites, coordinated in a bidentate manner, and between a metal site by a carboxyl group. According to the X-ray diffraction analysis, this compound is an interpenetrated 2D coordination polymer with pores along the crystallographic axis c. These small pores have interesting potential application in the adsorption of small gas molecules, such as H2.
    No preview · Article · Jun 2013 · Inorganica Chimica Acta
  • [Show abstract] [Hide abstract]
    ABSTRACT: A chemically modified tung oil was used as the main polyol component in the formulation of viscoelastic (low resilience) polyurethane foams. Rice Husk Ash (RHA), a residue from the rice process industry, was chosen to be incorporated as rigid filler in these materials because of its high silica content. Water was used as blowing agent in order to increase the green nature of the reinforced foams. Physico-chemical and thermal properties of the neat and reinforced foams were measured and analyzed. RHA addition leads to noticeable changes in several properties, mainly thermal conductivity, density and foam morphology, even at the low filler content used in this work. Although the thermal stability was almost unaffected by ash content, a stabilizing effect of the inorganic filler was identified, since the residual char was higher than predicted from theoretical calculations.
    No preview · Article · Apr 2013 · Polymer Testing