Rocío Castro-Ríos

Autonomous University of Nuevo León, San Nicolás de los Garza, Nuevo León, Mexico

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Publications (6)6.28 Total impact

  • Paolo Lucci · Rocío Castro-Ríos · Oscar Núñez
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    ABSTRACT: Fumonisins are mycotoxins produced by various Fusarium spp. Fungi (mainly Fusarium verticillioides and Fusarium proliferatum) commonly found in maize. They were first discovered in the late 80s by Gelderblon et al. who studied the incidence rate of esophageal cancer in the South African population. More than ten different fumonisins have been isolated and characterized. Of these, fumonisins B1, B2 and B3 (FB1, FB2 and FB3, respectively) are the major ones naturally occurring in maize or maize-based products. Fumonisins are toxic toward many different animals. Known animal diseases caused by these mycotoxins are hepatocarcinogenic effects of rats and mice, equine leukoencephalomalacia in horses, and pulmonary edema in pigs. However, their toxicity toward humans is still unclear. There is some evidence that fumonisins might be involved in the formation of esophageal cancer and might have a negative effect on neural tube development in embryos. The International Agency for Research on Cancer classified FB1 as a Group 2B carcinogen (possibly carcinogenic to humans). For these reasons, maximum levels for fumonisin contamination have been decreed by many countries. For instance, in the European Union, the maximum permitted levels for fumonisins (sum of FB1 and FB2) in maize and its derived products are 0.2 to 4 mg/Kg. Therefore, the development of analytical methodologies for the routine control of fumonisins in food is necessary. Various methodologies have been employed for the analysis of fumonisins. Although fumonisins molecules neither selectively absorb UV light nor exhibit any fluorescence, since they lack chromophores in their molecular structure, liquid chromatography (LC) with fluorescence detection have been employed after fumonisin derivatization into compounds that exhibit fluorescence. But nowadays, liquid chromatography-mass spectrometry (LC-MS(/MS)) and liquid chromatography-high resolution mass spectrometry (LC-HRMS) are the techniques of choice for the analysis and characterization of fumonisins in foodstuffs. However, it should be pointed out that regardless of the employed detection system, sample preparation procedures (especially extraction and clean-up procedures) is maybe the most important issue in the determination of fumonisins. Various extraction techniques have been reported for the clean-up and extraction of fumonisins including simple solid-liquid extraction (SLE), solid-phase extraction (SPE), immunoaffinity procedures, the use of molecularly imprinted polymers (MIPs), and even QuEChERS methods. This chapter will review the state-of-the-art of liquid chromatography-mass spectrometry techniques for the analysis and characterization of fumonisins in food-based products and other matrices. Because of their importance in fumonisin analysis, commonly used as well as novel sample treatment procedures will be addressed. LC-MS chromatographic conditions, ionization sources, and MS and HRMS analyzers frequently used, as well as strategies for the structural characterization and the qualitative and quantitative analysis of fumonisins will be discussed by means of relevant applications. Coverage of all kind of applications is beyond the scope of the present contribution, so we will focus on the most relevant applications published in the last years.
    No preview · Chapter · Apr 2015
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    ABSTRACT: In this review, the composition, actions, and clinical applications of acemannan in medicine and its effectiveness as an adjunct in the treatment of diseases are presented. An electronic literature search was performed up to January 2014 for studies and research presenting data to validate the efficacy of acemannan. A total of 50 titles, abstracts and full-text studies were selected and reviewed. Acemannan has various medicinal properties like osteogenic, anti-inflammatory, and antibacterial, which accelerate healing of lesions. Also, acemannan is known to have antiviral and antitumor activities in vivo through activation of immune responses. It was concluded that Aloe vera has immense potential as a therapeutic agent. Even though the plant is a promising herb with various clinical applications in medicine and dentistry, more clinical research needs to be undertaken to validate and explain the action of acemannan in healing, so that it can be established in the field of medicine and a more precise understanding of the biological activities of these is required to develop Aloe vera as a pharmaceutical source.
    Full-text · Article · Aug 2014 · Natural product communications
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    ABSTRACT: In research laboratories of both organic synthesis and extraction of natural products, every day a lot of products that can potentially introduce some biological activity are obtained. Therefore it is necessary to have in vitro assays, which provide reliable information for further evaluation in in vivo systems. From this point of view, in recent years has intensified the use of high-throughput screening assays. Such trials should be optimized and validated for accurate and precise results, i.e. reliable. The present review addresses the steps needed to develop and validate bioanalytical methods, emphasizing UV-Visible spectrophotometry as detection system. Particularly focuses on the selection of the method, the optimization to determine the best experimental conditions, validation, implementation of optimized and validated method to real samples, and finally maintenance and possible transfer it to a new laboratory.
    No preview · Article · Feb 2014
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    ABSTRACT: Poloxamers (PXMs) are amphiphilic non-ionic block polymers commonly used in the cosmetic and pharmaceutical industries. In spite of the wide use of PXMs, few studies have dealt with the analysis of these polymers in pharmaceutical preparations. In this work, high-performance thin-layer chromatography (HPTLC) has been used to quantify both PXM-188 and PXM-407 in pharmaceutical preparations. The separation of these compounds was carried out using reverse phase HPTLC plates with a chloroform-methanol mixture as the mobile phase. Detection was performed densitometrically using the Dragendorff's reagent for the visualization of PXMs. Quality parameters were established, and the detection limits ranged from 24 to 47ng/spot. A good precision (day to day and run to run), with relative standard deviations <11.18%, was obtained. The proposed method was satisfactorily applied to the analysis of laboratory-made and commercial pharmaceutical products.
    No preview · Article · Mar 2008 · Journal of Pharmaceutical and Biomedical Analysis
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    ABSTRACT: We have developed a solid-phase microextraction procedure for polycyclic aromatic hydrocarbons. A simplex experimental design was employed to optimize the process. A polydimethylsiloxane/divinylbenzene fiber was selected. The optimum conditions were: an extraction step in the immersion mode, over a period of 60min at 70 degrees C using high-speed stirring, and an 8min desorption step using acetonitrile (90 mu l). Linear relationships were obtained for all compounds, except for naphthalene. Our method showed a good precision and accuracy with a detection limit between 0.005 and 0.306 mu g1(-1). Our method was used to detect PAHs in real water samples.
    No preview · Article · Jan 2008 · Analytical Letters
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    ABSTRACT: The aim of this work is to establish a sensitive and reliable method for the analysis of the 16 priority Environmental Protection Agency-defined polycyclic aromatic hydrocarbons (PAHs) found in water samples. Gas chromatography (GC)-mass spectrometry (MS) and high-performance liquid chromatography (HPLC)-fluorescence detection (FLD)-UV techniques are optimized to obtain an adequate resolution of all compounds. Validation of the methods is carried out, and a good performance is observed for both techniques. The HPLC-FLD-UV technique is somewhat more sensitive than the GC-MS technique for the determination of PAHs; thus, the HPLC-FLD-UV method is used to follow up both the solid-phase extraction (SPE) analysis using cartridges and discs and the liquid-liquid extraction (LLE), which are also evaluated for the extraction of the PAHs. Low recoveries between 43% and 79% are obtained using SPE cartridges, and higher values are obtained using SPE discs (56-96%) and LLE (60-105%). Better results are obtained using the LLE technique, and, thus, analysis of real water samples is carried out using this technique. LODs between 0.6 and 21 ng/L and relative standard deviations less than 15% are obtained using a spiked water sample analyzed using the full LLE HPLC-FLD-UV method.
    Full-text · Article · Feb 2007 · Journal of chromatographic science