Nuestros investigadores

Elena Lizarraga Pérez

Departamento
Facultad de Farmacia y Nutrición. Universidad de Navarra
Líneas de investigación
Análisis instrumental, cromatografía de líquidos, cromatografía de gases, electroforesis capilar, micotoxinas, alimentos, validación métodos analíticos, estabilidad de medicamentos

Publicaciones científicas más recientes (desde 2010)

Autores: Arce-Lopez, Beatriz; Lizarraga, Elena; et al.
Revista: TALANTA
ISSN 1873-3573  Vol. 206  2020 
We report the methodology for the quantification of 19 mycotoxins in human plasma using high performance liquid chromatography-mass spectrometry (triple quadrupole). The studied mycotoxins were: deepoxy-deoxynivalenol, aflatoxins (B1, B2, G1, G2 and M1), T-2 and HT-2, ochratoxins A and B, zearalenone, sterigmatocystin, nivalenol, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, neosolaniol, diacetoxyscirpenol and fusarenon-X. Sample deproteinization and cleanup were performed in one step using Captiva EMR-lipid (3 mL) cartridges and acetonitrile (with 1% formic acid). The extraction step was simple and fast. Validation was based on the evaluation of limits of detection (LOD) and quantification, linearity, precision, recovery, matrix effect, and stability. LOD values ranged from 0.04 ng/mL for aflatoxin B1 to 2.7 ng/mL for HT-2, except for nivalenol, which was 9.1 ng/mL. Recovery was obtained in intermediate precision conditions and at three concentration levels. Mean values ranged from 68.8% for sterigmatocystin to 97.6% for diacetoxyscirpenol (RDS <= 15% for all the mycotoxins). Matrix effects (assessed at three concentration levels and in intermediate conditions) were not significant for most of the mycotoxins and were between 75.4% for sterigmatocystin and 109.3% for ochratoxin B (RDS <= 15% for all the mycotoxins). This methodology will be useful in human bio-monitoring studies of mycotoxins for its reliability.
Autores: González-Peñas, E., (Autor de correspondencia); Vettorazzi, Ariane Renata; Lizarraga, Elena; et al.
Revista: TOXINS
ISSN 2072-6651  Vol. 11  Nº 7  2019 
Autores: Palop, Juan Antonio; Sanmartín, María del Carmen; et al.
Revista: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
ISSN 1388-6150  Vol. 127  Nº 2  2017  págs. 1663 - 1674
The fusion and thermal decomposition of thirty-three diselenide compounds with a urea, thiourea or selenourea group linked with different aliphatic or aromatic substituents have been studied by thermogravimetry, differential scanning calorimetry and mass spectrometry in order to perform comparative thermal stability studies among analogs. A relationship has been found between stability and a series of effects which occur in the compound structures. Analysis of the thermal data indicated that: (a) in general, compounds with a urea or selenourea group are more stable than those with a thiourea group; (b) no difference in stability exists when an aromatic or aliphatic group is linked to the thiourea group but when linked to the urea or selenourea groups, stability does differ; (c) selenourea compounds with aliphatic chain are the most unstable; and (d) the nature of the substituent located on the benzyl ring has no effects on thermal stability. Therefore, criteria for the selection of substituents can be established in order to improve the stability of these drugs. In addition, the mass spectral fragmentation in comparison with thermal analytical data helps in confirming the thermal behavior of the compounds.
Autores: Lizarraga, Elena; Zabaleta, C.; Palop, Juan Antonio;
Revista: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
ISSN 1388-6150  Vol. 127  Nº 2  2017  págs. 1655 - 1661
The thermal hazard of a series of quinoxaline 1,4-di-N-oxide derivatives, designed to act as prodrugs, whose chemical structure undergoes a very rapid decomposition, has been evaluated. The fusion and thermal decomposition of the compounds have been studied by thermogravimetry, differential scanning calorimetry, and mass spectrometry (MS-DIP). The results obtained indicate that the decomposition process from the loss of one of the oxygens linked to a nitrogen of the quinoxaline involves the release of a large quantity of vapor in a very small time interval. The enthalpy is higher than 300 J g(-1); in some cases, it is around 1000 J g(-1).
Autores: Santivañez, Mery Jhenny; Moreno-Viguri, Elsa; Pérez-Silanes, S; et al.
Revista: JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES
ISSN 1570-0232  Vol. 1061  2017  págs. 225 - 232
The development and validation of an analytical method for the simultaneous analysis of five neutral lipids in Trypanosoma cruzi epimastigotes by GC-MS is presented in this study. The validated method meets all validation parameters for all components and the chromatographic conditions have been optimized during its development. This analytical method has demonstrated good selectivity, accuracy, within-day precision, recovery and linearity in each of the established ranges. In addition, detection and quantification limits for squalene, cholesterol, ergosterol and lanosterol have been improved and it is worth highlighting the fact that this is the first time that squalene-2,3-epoxide validation data have been reported. The new validated method has been applied to epimastigotes treated with compounds with in vitro anti-T.cruzi activity. This new methodology is straightforward and constitutes a tool for screening possible sterol biosynthesis pathway inhibitors in Trypanosoma cruzi, one of the most studied targets in Chagas disease treatment. Therefore, it is an interesting and useful contribution to medicinal chemistry research.
Autores: Alcolea, Verónica; Palop, Juan Antonio; et al.
Revista: MOLECULES
ISSN 1420-3049  Vol. 22  Nº 8  2017  págs. 1314
The physicochemical properties of a compound play a crucial role in the cancer development process. In this context, polymorphism can become an important obstacle for the pharmaceutical industry because it frequently leads to the loss of therapeutic effectiveness of some drugs. Stability under manufacturing conditions is also critical to ensure no undesired degradations or transformations occur. In this study, the thermal behaviour of 40 derivatives of a series of sulphur and selenium heteroaryl compounds with potential antitumoural activity were studied. In addition, the most promising cytotoxic derivatives were analysed by a combination of differential scanning calorimetry, X-ray diffraction and thermogravimetric techniques in order to investigate their polymorphism and thermal stability. Moreover, stability under acid, alkaline and oxidative media was tested. Degradation under stress conditions as well as the presence of polymorphism was found for the compounds VA6E and VA7J, which might present a hurdle to carrying on with formulation. On the contrary, these obstacles were not found for derivative VA4J.
Autores: Palop, Juan Antonio; Sanmartín, María del Carmen; et al.
Revista: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
ISSN 1388-6150  Vol. 123  Nº 3  2016  págs. 1951 - 1962
Trace element selenium and its metabolites have received a great deal of attention with regard to the development of new therapies for both cancer prevention and treatment. Following this approach, our research group has synthesized a series of novel selenocarbamates derivatives. We present thermal analysis of the novel compounds, performed with differential scanning calorimetry and thermogravimetric analysis. Relationship is found among thermal analytical data and structure of the different series of compounds. These data allow establishing criteria for the selection of substituents that improve the stability. The most thermally unstable compounds are those with higher cytotoxic activities, suggesting that the release of methylselenol could be implicated in the biological activity.
Autores: Lizarraga, Elena; de Cerain, A.L.; et al.
Revista: FOOD CONTROL
ISSN 0956-7135  Vol. 53  2015  págs. 163 - 176
Mycotoxins can cause toxicity when ingested by humans and animals. Although the rumen is supposed to be a barrier against mycotoxins, some studies demonstrate that carry-over of mycotoxins to milk is possible. Different studies have found mycotoxin levels in animal milk, mainly related to contaminated feed for ruminants. Aflatoxin M1 is the most studied mycotoxin in milk and levels exceeding the EU maximum level for this mycotoxin in this matrix (0.050 mu g/kg) have been found. Maximum levels in milk for other mycotoxins have not been established; however ochratoxin A, aflatoxins G1, G2, B1, B2 and M2, fumonisin B1, cyclopiazonic acid, zearalenone and its metabolites and deepoxy-deoxynivalenol have also been found in milk samples. Taking into account that multi-exposure to mycotoxins is the most likely scenario and co-occurrence of mycotoxins could affect their toxicological effects in humans and animals, there is a need to determine the co-occurrence of mycotoxins in milk.
Autores: Plano, Daniel; Palop, Juan Antonio; et al.
Revista: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
ISSN 1388-6150  Vol. 111  Nº 1  2013  págs. 605-610
Differential scanning calorimetry (DSC) and thermogravimetry (TG) are analytical and quantitative methods capable of providing reliable, fast and reproducible results. These data allow establishing the thermal stability, purity degree and the polymorphic behavior of organic compounds. Thermal analysis of fusion and degradation processes was carried out on organonitrogen, organosulfur and organoselenium phthalazine derivatives to establish thermal stability criteria. Decomposition and fusion temperatures of 27 biological active compounds, synthesized by our research group were determined using TG and DSC. Analysis of the thermal data indicated that: (a) in general, nitrogen compounds are more stable than sulfur and selenium compounds; (b) thioderivatives possess degradation temperatures higher than selenium compounds; (c) the presence of selenium atoms in molecular structure has associated a minor thermal stability; (d) sulfide derivatives decomposition process have higher T-onset values than disulfide compounds; (e) there are differences in the stability due to groups selenol, methylseleno, and cyanoseleno; (f) the nature of the substituent located on the benzyl ring has no effects on selenophthalazines thermal stability.
Autores: Font, María ; Lizarraga, Elena; Ibáñez, Elena; et al.
Revista: EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY
ISSN 0223-5234  Vol. 66  2013  págs. 489 - 498
A molecular modelling study has been carried out on a previously reported series of symmetrically substituted bisacylimidoselenocarbamate (BSeC) derivatives that show remarkable antitumour activity in vitro against a panel of human tumour cell lines. These derivatives can be considered as a central scaffold constructed around a methyl carbamimidoselenoate nucleus in which two heteroarylacyl fragments are located on the scaffold nitrogen atoms, thus forming the different BSeCs. The results reveal that the nature of the selected heteroaryl ring has a marked influence on the antiproliferative activity of the compounds and this can be related, as a first approximation, to the ability to release methylselenol (MeSeH), a compound that, according to our initial hypothesis, is ultimately responsible for the antitumour activity of the compounds under investigation. The release of MeSeH from the active BSeCs has been confirmed by means of Head Space Gas Chromatography Mass Spectrometry techniques. The data that support this connection include the topography of the molecules, the conformational behaviour of the compounds, which influences the accessibility of the hydrolysis point, the interaction map obtained for an O2H type probe, and the location and energy of the HOMO/LUMO orbitals.
Autores: Irigoyen, Ángel María; González-Peñas, E.; et al.
Revista: FOOD CONTROL
ISSN 0956-7135  Vol. 32  Nº 1  2013  págs. 63 - 68
The co-occurrence of ochratoxin A (OTA) and its five analogs (OTB, OTC, MeOTA, MeOTB and EtOTB) in 96 red wine samples from Mediterranean countries has been demonstrated, for the first time, in this study. OTA was detected in 99% of the samples (<LOD - 455 ng L-1). This mycotoxin appeared simultaneously with OTB (2.05-119 ng L-1) in all the samples and in 89.6% of them OTC (<LOD - 31.5 ng L-1) also accompanied both. OTB appears at comparable levels and incidence just like OTA does, and OTC median concentration is approximately 10% of that of OTA. A high statistical association was found between the concentrations of OTA OTB and OTA OTC. MeOTA, MeOTB and EtOTB were detected in 62.5, 83.3 and 83.3% of the samples, respectively. In 44.8% of the wines, the 6 ochratoxins appeared simultaneously. There was no evidence for ochratoxin A levels being greater in wines from Southern Europe than those described from North Europe. Samples from North Africa presented statistically the highest values for OTA, OTB, OTC and EtOTB.
Autores: Ibáñez, María; González-Peñas, E.; Lizarraga, Elena; et al.
Revista: FOOD CHEMISTRY
ISSN 0308-8146  Vol. 132  Nº 1  2012  págs. 35-42
One-hundred and twenty-three barley samples from a region of Spain (Navarra) were analysed in order to evaluate the possible co-occurrence of aflatoxins (AFB1, AFG1, AFB2 and AFG2), ochratoxin A (OTA) and zearalenone (ZEA). The results indicated that 80% of the samples presented detectable, although very low levels, of two or more mycotoxins. The most frequent combinations were AFB1 and OTA; AFB1, ZEA and OTA; and AFB1 and ZEA. In general, the statistical study did not show significant differences between levels or incidence for the mycotoxins in different years of harvest, variety of barley, farming or origin. The calculated values for daily intake were low and the risk to consumers could be assumed to be very low. However, the co-occurrence of several mycotoxins, and therefore synergic or additive effects, should be taken into account when determining permitted levels or risk assessment. (C) 2011 Elsevier Ltd. All rights reserved.
Autores: Ibáñez, María; González-Peñas, E.; Lizarraga, Elena; et al.
Revista: FOOD CONTROL
ISSN 0956-7135  Vol. 28  Nº 2  2012  págs. 295-298
In this paper, a statistical overview of the simultaneous presence of 14 mycotoxins in Spanish barley is presented. The co-occurrence of more than two mycotoxins has been observed in 95% of the samples. From a descriptive standpoint, the results show that the most common combinations were AFB1, OTA and DON (29%), and AFB1, OTA, DON and ZEA (26%), although other combinations could also occur. However, the statistical study determined that other associations had a higher impact or importance. Four factors or combinations of variables could explain the 63% of variability found for the samples. These factors were the associations of: type-B trichothecenes and DAS; type-A trichothecenes and NIV; AFB1, AFG1 and ZEA; and AFB2 and AFG2. The toxin-producing fungi and environmental conditions have been essential in explaining the associations between the toxins. (C) 2012 Elsevier Ltd. All rights reserved.
Autores: González-Peñas, E.; Lizarraga, Elena; et al.
Revista: FOOD CONTROL
ISSN 0956-7135  Vol. 27  Nº 1  2012  págs. 139 - 145
Ochratoxin A (OTA), B (OTB) and their methyl (MeOTA, MeOTB) and ethyl (OTC, EtOTB) esters were evaluated in 51 red wine samples from Navarra (Spain). Detectable levels of OTA and OTB were found in 100% of the samples, and 71% showed the presence of OTC. The six ochratoxins appeared simultaneously in 18% of the samples. Results indicated that OTC is hydrolyzed to OTA in red wine. Therefore, ochratoxin intake from wine can be underestimated when only assessed by OTA analysis. Analyzed Navarra wines are scarcely contaminated with ochratoxins and their contribution to human intake is low, with the worst case being 4.7% and 6.6% of the provisional tolerable weekly intake (PTWI) for OTA and for the sum of ochratoxins, respectively. No significant differences were generally found between vintages. With the exception of OTA, no significant differences were observed between organic and traditional farming. Levels of ochratoxins were positively correlated with temperature and inversely correlated with humidity and rainfall.
Autores: Ibáñez, María; Lizarraga, Elena; González-Peñas, E.; et al.
Revista: FOOD CONTROL
ISSN 0956-7135  Vol. 25  Nº 1  2012  págs. 81-88
In this survey, 123 barley samples from a northern region of Spain (Navarra) have been analyzed for co-occurrence of eight type-A and type-B trichothecenes (DON, NIV, 3-ADON, 15-ADON, FUS-X, T-2, HT-2 and DAS). Samples were classified according to place and year of harvest (2007 and 2008), type of farming (organic or traditional) and variety of barley. The rains during anthesis had a great influence on the trichothecene levels, observing higher contaminations in samples collected during 2008. In addition, type-A trichothecenes tend to be more present in cooler areas, while type-B appears more often in warmer regions. The type of farming has not led to significant differences in mycotoxins levels, although a trend toward higher incidence and contamination in traditional samples has been observed. On the other hand, it was observed that Pewter, the favorite barley variety for the malting industry in Spain, has been the most susceptible to contamination with trichothecenes. (c) 2011 Elsevier Ltd. All rights reserved.
Autores: Plano, Daniel; et al.
Revista: CHEMICAL RESEARCH IN TOXICOLOGY
ISSN 0893-228X  Vol. 25  Nº 11  2012  págs. 2479-2489
In the search for new molecules with potential antiangiogenic activity, we found that several imidoselenocarbamate derivatives effectively suppressed the expression of vascular endothelial growth factor (VEGF) induced by hypoxia in NCI-H157 tumor cells. Mechanistic studies indicated that these compounds inhibited STAT3 phosphorylation triggered by hypoxia, suggesting that inhibition of STAT3 function may play a role in VEGF inhibition. Moreover, these molecules showed interesting proapoptotic and antiproliferative effects. Both the presence of selenium, but not sulfur, and the nature of the radical substituents were important for activity. Interestingly, under hypoxic conditions, several methyl imidoselenocarbamate derivatives released methylselenol, a highly reactive and cytotoxic gas, which was responsible for their biological activities. The kinetics of the release of methylselenol by these molecules was highly dependent on the nature of the substituent radicals and correlated with their early proapoptotic activity. Our results support the notion that pharmacological activities reported for methyl imidoselenocarbamate derivatives are dependent on the release of methylselenol. Given the well-known antitumor activities of this compound, imidoselenocarbamate derivatives represent a promising approach to develop new drugs that release methylselenol in a controlled way.
Autores: Ibáñez, María; Martínez, R.; González-Peñas, E.; et al.
Revista: FOOD CONTROL
ISSN 0956-7135  Vol. 22  Nº 12  2011  págs. 1949 - 1955
Forty-six breakfast cereal samples from the Spanish market have been analyzed for the occurrence of aflatoxins (AFB1, AFG1, AFB2 and AFG2), ochratoxin A (OTA) and zearalenone (ZEA). According to the results, 9% of the samples were contaminated with AFB1 although no sample exceeded the LOQ (0.2 mu g kg(-1)), and no sample presented detectable levels of the other aflatoxins (AFB2, AFG1 and AFG2). Zearalenone and OTA contaminated 48 and 39% of the samples, respectively, with mean values of the samples having quantification levels of 25.40 and 0.37 mu g kg(-1), respectively. The co-occurrence of OTA and ZEA was observed in 28% of the samples. Aflatoxin B1 appeared only in the corn-based breakfast cereals, whereas ZEA and OTA showed the highest contamination rates in the samples containing wheat and wheat and rice, respectively. No sample of high-fiber content was contaminated with AFB1, whereas OTA and ZEA occurred with higher incidence in high-fiber content samples. Moreover, the daily exposure to AFB1, OTA and ZEA is discussed.
Autores: Plano, Daniel; Lizarraga, Elena; Palop, Juan Antonio; et al.
Revista: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
ISSN 1388-6150  Vol. 105  Nº 3  2011  págs. 1007 - 1013
The thermal behavior of a series of organosulfur and organoselenium compounds has been studied by means of differential scanning calorimetry, X-ray diffraction, and thermomicroscopy in order to investigate their polymorphism. In this study, the polymorphism of some of the products has been established. The results of the experiments show that there are four types of thermal behavior for compounds studied. The physicochemical characterization of sulfur and selenium compounds showed differences in structural parameters and fusion temperatures among polymorphic forms.
Autores: Ibáñez, María; Lizarraga, Elena; González-Peñas, E.;
Revista: FOOD CONTROL
ISSN 0956-7135  Vol. 22  Nº 8  2011  págs. 1428 - 1434
A validated method for the simultaneous determination of eight type-A and type-B trichothecenes in barley has been applied to the analysis of 44 samples from the 2007 harvest in Navarra (Spain). The procedure included simultaneous extraction of trichothecenes with acetonitrile and water (84:16), clean up with Multisep columns, derivatization of the extract and GC-MS analysis. During method validation, selectivity, linearity, precision and accuracy, limits of detection and quantification and recovery were evaluated. Recovery ranged from 92.0 to 101.9% (RSD < 15%), except for nivalenol (NIV) (63.1%), and the limits of detection and quantification ranged from 0.31 to 3.87 mu g kg(-1) and from 10 to 20 mu g kg(-1), respectively. The higher occurrence was found for deoxynivalenol (DON) (89% of the samples), although at concentrations below the maximum permitted level. The calculated dietary intakes of DON, NIV and the sum of T-2 and HT-2 were below the TDI values proposed. Two or more trichothecenes were present in 41% of the samples and so, the mycotoxin co-occurrence, and therefore synergic or additive effects, should be taking into account when determining permitted levels or risk assessment.
Autores: Ibáñez, María; et al.
Revista: FOOD CHEMISTRY
ISSN 1873-7072  Vol. 127  Nº 1  2011  págs. 351 - 358
A fast and simple UHPLC-FLD method has been developed for the simultaneous determination in barley of aflatoxins (B1, G1, B2 and G2), ochratoxin A (OTA) and zearalenone (ZEA), some of the most important mycotoxins due to their toxicity and occurrence. The procedure is based on the extraction of the six mycotoxins with a mixture of acetonitrile and water, and the purification of the extract with immunoaffinity columns before analysis. Detection of AFB1 and AFG1 is improved using a photochemical reaction. The method has been validated with satisfactory results. Limits of detection were 340 ng kg(-1) for ZEA, 13 ng kg(-1) for OTA and varied from 0.5 to 15 ng kg(-1) for aflatoxins. Recovery percentages were between 78.2% and 109.2%. After being validated, the method has been successfully applied to 20 barley samples cultivated in a region of northern Spain (Navarra).
Autores: Ibáñez, María; González-Peñas, E.; et al.
Revista: JOURNAL OF CHROMATOGRAPHY A
ISSN 0021-9673  Vol. 1217  Nº 52  2010  págs. 8249 - 8256
A validated high-performance liquid chromatography (HPLC) method with fluorescence detection for the simultaneous quantification of ochratoxin A (OTA) and its analogues (ochratoxin B (OTB), ochratoxin C (OTC) and methyl ochratoxin A (MeOTA)) in red wine at trace levels is described. Before their analysis by HPLC-FLD, ochratoxins were extracted and purified with immunoaffinity columns from 50 mL of red wine at pH 7.2. Validation of the analytical method was based on the following parameters: selectivity, linearity. robustness, limits of detection and quantification, precision (within-day and between-day variability), recovery and stability. The limits of detection (LOD) in red wine were established at 0.16, 0.32. 0.27 and 0.17 ng L(-1) for OTA, OTB, MeOTA and OTC, respectively. The limit of quantification (LOQ) was established as 0.50 ng L(-1) for all of the ochratoxins. The LOD and LOQ obtained are the lowest found for OTA in the reference literature up to now. Recovery values were 93.5, 81.7, 76.0 and 73.4% for OTA, OTB, MeOTA and OTC, respectively. For the first time, this validated method permits the investigation of the co-occurrence of ochratoxins A. B. C and methyl ochratoxin A in 20 red wine samples from Spain