Grethel León-Mejía
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Research Interests
Grethel León-Mejía has a total of 130 co-authors. Here are the top co-authors by number of shared publications:
- Juliana da Silva
Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970, Brazil
10 shared publications Milton Quintana-Sosa
Facultad de Ciencias Básicas, Centro de Investigaciones en Ciencias de La Vida (CICV), Universidad Simón Bolívar, Barranquilla, Colombia
6 shared publicationsAlvaro Miranda-Guevara
Facultad de Ciencias Básicas, Centro de Investigaciones en Ciencias de La Vida (CICV), Universidad Simón Bolívar, Barranquilla, Colombia
5 shared publicationsAntonio Acosta-Hoyos
Facultad de Ciencias Básicas, Centro de Investigaciones en Ciencias de La Vida (CICV), Universidad Simón Bolívar, Barranquilla, Colombia
5 shared publicationsJoão Antonio Pêgas Henriques
Programa de Pós-Graduação em Genética e Biologia Molecular (PPGBM), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil
5 shared publicationsAndreas Hartmann
Novartis Pharma AG, Basel, Switzerland
4 shared publications
Latest Publications
- Open Access
- 16 May 2026
- Published by Elsevier in Mutation Research - Genetic Toxicology and Environmental Mutagenesis
- Vol. 912, 503940
Alkaline comet assay in human biomonitoring studies by the Latin America / LA-COMET group
- 16 May 2026
- Published by Elsevier in Mutation Research - Genetic Toxicology and Environmental Mutagenesis
- Vol. 912, 503940
Open AccessAlkaline comet assay in human biomonitoring studies by the Latin America / LA-COMET group
- 12 May 2026
- Published by Elsevier in Mutation Research - Genetic Toxicology and Environmental Mutagenesis
- Vol. 912, 503939
Analysis of the trends in in vitro studies of the Latin America-Comet assay (LA-COMET) Group
- 12 May 2026
- Published by Elsevier in Mutation Research - Genetic Toxicology and Environmental Mutagenesis
- Vol. 912, 503939
Analysis of the trends in in vitro studies of the Latin America-Comet assay (LA-COMET) Group
- Open Access
- 28 April 2026
- Published by Springer Nature in Archives of Toxicology
- Vol. 100 (8) , 1-15
Assessment of cytotoxicity and genomic instability induced by coal-derived nanoparticles in V79 and HaCaT Cells
Coal is a major global energy resource, but its extraction raises significant environmental and health concerns. Mining activities release large amounts of particulate matter, including nanoparticles (NPs), into the environment. These NPs are hazardous due to their content of polycyclic aromatic hydrocarbons (PAHs), metals, oxides, and other compounds capable of disrupting cellular and molecular processes. This study evaluated the cytotoxic and genotoxic effects of coal-derived NPs on V79 and HaCaT cell lines, focusing on their impact on DNA stability and the mechanisms responsible for cellular damage. NPs were isolated using an acid-based separation method and applied to cells at concentrations of 50, 150, and 300 μg/mL. Atomic force microscopy (AFM) provided topographical characterization, while dynamic light scattering (DLS) confirmed their tendency to agglomerate. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) confirmed NP morphology and elemental composition, including carbon, oxygen, iron, calcium, silicon, aluminum, and copper. Cytotoxicity was assessed using resazurin and sulforhodamine B assays, and genotoxicity was evaluated using the comet assay, micronucleus test, and γH2AX immunostaining. Results showed a clear dose-dependent effect, with coal NPs inducing genomic instability and increased cell mortality, mainly through apoptosis. These findings highlight the importance of characterizing coal-derived NPs to better assess their environmental and health risks, particularly regarding respiratory diseases.
- 28 April 2026
- Published by Springer Nature in Archives of Toxicology
- Vol. 100 (8) , 1-15
Open AccessAssessment of cytotoxicity and genomic instability induced by coal-derived nanoparticles in V79 and HaCaT Cells
Coal is a major global energy resource, but its extraction raises significant environmental and health concerns. Mining activities release large amounts of particulate matter, including nanoparticles (NPs), into the environment. These NPs are hazardous due to their content of polycyclic aromatic hydrocarbons (PAHs), metals, oxides, and other compounds capable of disrupting cellular and molecular processes. This study evaluated the cytotoxic and genotoxic effects of coal-derived NPs on V79 and HaCaT cell lines, focusing on their impact on DNA stability and the mechanisms responsible for cellular damage. NPs were isolated using an acid-based separation method and applied to cells at concentrations of 50, 150, and 300 μg/mL. Atomic force microscopy (AFM) provided topographical characterization, while dynamic light scattering (DLS) confirmed their tendency to agglomerate. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) confirmed NP morphology and elemental composition, including carbon, oxygen, iron, calcium, silicon, aluminum, and copper. Cytotoxicity was assessed using resazurin and sulforhodamine B assays, and genotoxicity was evaluated using the comet assay, micronucleus test, and γH2AX immunostaining. Results showed a clear dose-dependent effect, with coal NPs inducing genomic instability and increased cell mortality, mainly through apoptosis. These findings highlight the importance of characterizing coal-derived NPs to better assess their environmental and health risks, particularly regarding respiratory diseases.
- Open Access
- 18 July 2025
- Published by MDPI AG in Antioxidants
- Vol. 14 (7) , 881
Guarana, Selenium, and L-Carnitine Supplementation Improves the Oxidative Profile but Fails to Reduce Tissue Damage in Rats with Osteoarthritis
Osteoarthritis (OA) is a progressive joint disease that is commonly managed with palliative drugs, many of which are associated with undesirable side effects. This study investigated the therapeutic potential of a novel supplementation with guarana, selenium, and L-carnitine (GSC) in a rat model of chemically induced OA. Forty male Wistar rats (8–9 weeks old) received intra-articular sodium monoiodoacetate (Mia) to induce OA, and were subsequently treated with GSC. Inflammatory and oxidative stress parameters were analyzed at the end of the experiment. GSC supplementation enhanced endogenous antioxidant defenses, suggesting systemic antioxidant activity. However, no histological improvement was observed. In silico analyses indicated that Mia-induced OA may involve a complex molecular environment that GSC, at the tested dose, failed to modulate at the site of injury. Despite the limited local effects, these findings support the systemic benefits of GSC and highlight the potential of natural compound-based strategies in OA management. Given the adverse effects of conventional pharmacotherapy, the development of alternative, naturally derived treatments remains a promising avenue for future research.
- 18 July 2025
- Published by MDPI AG in Antioxidants
- Vol. 14 (7) , 881
Open AccessGuarana, Selenium, and L-Carnitine Supplementation Improves the Oxidative Profile but Fails to Reduce Tissue Damage in Rats with Osteoarthritis
Osteoarthritis (OA) is a progressive joint disease that is commonly managed with palliative drugs, many of which are associated with undesirable side effects. This study investigated the therapeutic potential of a novel supplementation with guarana, selenium, and L-carnitine (GSC) in a rat model of chemically induced OA. Forty male Wistar rats (8–9 weeks old) received intra-articular sodium monoiodoacetate (Mia) to induce OA, and were subsequently treated with GSC. Inflammatory and oxidative stress parameters were analyzed at the end of the experiment. GSC supplementation enhanced endogenous antioxidant defenses, suggesting systemic antioxidant activity. However, no histological improvement was observed. In silico analyses indicated that Mia-induced OA may involve a complex molecular environment that GSC, at the tested dose, failed to modulate at the site of injury. Despite the limited local effects, these findings support the systemic benefits of GSC and highlight the potential of natural compound-based strategies in OA management. Given the adverse effects of conventional pharmacotherapy, the development of alternative, naturally derived treatments remains a promising avenue for future research.
- Open Access
- 2 July 2025
- Published by Asociacion Espanola de Ecologia Terrestre (AEET) in Ecosistemas
- p. 2865
Evaluación de la genotoxicidad inducida por algunos metales presentes en aguas fluviales: Un Estudio con Allium cepa en el Cesar-Colombia
Las actividades antropogénicas tienen un impacto significativo en los ecosistemas acuáticos en muchas regiones de Colombia. En este estudio, se evaluó la genotoxicidad del agua de dos ríos importantes de la región de La Loma – Cesar: el río Calenturitas y el río Cesar, utilizando el modelo biológico Allium cepa. Se recolectaron muestras de agua en diferentes puntos durante las épocas seca y lluviosa, realizando análisis macroscópicos y microscópicos para observar cambios en la viabilidad celular tras exposiciones de 24 y 48 horas. Los análisis químicos realizados mediante espectrofotometría de absorción atómica revelaron la presencia de mercurio y arsénico en el agua, lo que resultó en efectos adversos sobre el crecimiento y la división celular en A. cepa. Entre los hallazgos se destacan la disminución del índice mitótico, la formación de micronúcleos y la desintegración nuclear, indicativa de muerte celular. Además, se observó una reducción significativa en la longitud de la raíz y en el número de células que completaron la telofase. Estos resultados sugieren que los contaminantes presentes en los cuerpos de agua estudiados tienen un efecto genotóxico y citotóxico constante, independientemente de la variación estacional. La persistencia de estos contaminantes resalta la necesidad urgente de implementar medidas de control más rigurosas y estudiar los efectos a largo plazo en los ecosistemas acuáticos de la región.
- 2 July 2025
- Published by Asociacion Espanola de Ecologia Terrestre (AEET) in Ecosistemas
- p. 2865
Open AccessEvaluación de la genotoxicidad inducida por algunos metales presentes en aguas fluviales: Un Estudio con Allium cepa en el Cesar-Colombia
Las actividades antropogénicas tienen un impacto significativo en los ecosistemas acuáticos en muchas regiones de Colombia. En este estudio, se evaluó la genotoxicidad del agua de dos ríos importantes de la región de La Loma – Cesar: el río Calenturitas y el río Cesar, utilizando el modelo biológico Allium cepa. Se recolectaron muestras de agua en diferentes puntos durante las épocas seca y lluviosa, realizando análisis macroscópicos y microscópicos para observar cambios en la viabilidad celular tras exposiciones de 24 y 48 horas. Los análisis químicos realizados mediante espectrofotometría de absorción atómica revelaron la presencia de mercurio y arsénico en el agua, lo que resultó en efectos adversos sobre el crecimiento y la división celular en A. cepa. Entre los hallazgos se destacan la disminución del índice mitótico, la formación de micronúcleos y la desintegración nuclear, indicativa de muerte celular. Además, se observó una reducción significativa en la longitud de la raíz y en el número de células que completaron la telofase. Estos resultados sugieren que los contaminantes presentes en los cuerpos de agua estudiados tienen un efecto genotóxico y citotóxico constante, independientemente de la variación estacional. La persistencia de estos contaminantes resalta la necesidad urgente de implementar medidas de control más rigurosas y estudiar los efectos a largo plazo en los ecosistemas acuáticos de la región.
- Open Access
- 25 December 2023
- Published by MDPI AG in Scientia Pharmaceutica
- Vol. 92 (1) , 2
Polymorphisms in Drug Transporter and Metabolism Genes Associated with Resistance to Imatinib in Chronic Myeloid Leukemia: A Systematic Review and Meta-Analysis
The aim of this study was to establish the relationship between different polymorphisms in drug transporter and metabolizer genes and resistance to imatinib in chronic myeloid leukemia (CML). For this purpose, an exhaustive search was carried out in the Scopus, Web of Science, and PubMed databases using different combinations of keywords with different inclusion and exclusion criteria. The meta-analysis included nine studies that met the established criteria. The results of the study showed that the polymorphic variants AG and GG of CYP3A5*3 are associated with response to treatment, presenting a significantly lower risk with resistance to imatinib. Likewise, the variants T1236C and G2677T/A of the ABCB1 gene show a significant association with treatment efficacy. In addition, the genetic polymorphism 1236T, homozygous CC of the MDR1 gene, significantly influences the increased risk of cytogenetic relapse and the polymorphic variant 361G>A GA of the SLCO1A2 gene significantly affects the complete molecular response.
- 25 December 2023
- Published by MDPI AG in Scientia Pharmaceutica
- Vol. 92 (1) , 2
Open AccessPolymorphisms in Drug Transporter and Metabolism Genes Associated with Resistance to Imatinib in Chronic Myeloid Leukemia: A Systematic Review and Meta-Analysis
The aim of this study was to establish the relationship between different polymorphisms in drug transporter and metabolizer genes and resistance to imatinib in chronic myeloid leukemia (CML). For this purpose, an exhaustive search was carried out in the Scopus, Web of Science, and PubMed databases using different combinations of keywords with different inclusion and exclusion criteria. The meta-analysis included nine studies that met the established criteria. The results of the study showed that the polymorphic variants AG and GG of CYP3A5*3 are associated with response to treatment, presenting a significantly lower risk with resistance to imatinib. Likewise, the variants T1236C and G2677T/A of the ABCB1 gene show a significant association with treatment efficacy. In addition, the genetic polymorphism 1236T, homozygous CC of the MDR1 gene, significantly influences the increased risk of cytogenetic relapse and the polymorphic variant 361G>A GA of the SLCO1A2 gene significantly affects the complete molecular response.
- Open Access
- 4 August 2023
- Published by Springer Nature in Environmental Geochemistry and Health
- Vol. 45 (10) , 7081-7097
The dangerous link between coal dust exposure and DNA damage: unraveling the role of some of the chemical agents and oxidative stress
Exposure to coal mining dust poses a substantial health hazard to individuals due to the complex mixture of components released during the extraction process. This study aimed to assess the oxidative potential of residual coal mining dust on human lymphocyte DNA and telomeres and to perform a chemical characterization of coal dust and urine samples. The study included 150 individuals exposed to coal dust for over ten years, along with 120 control individuals. The results revealed significantly higher levels of DNA damage in the exposed group, as indicated by the standard comet assay, and oxidative damage, as determined by the FPG-modified comet assay. Moreover, the exposed individuals exhibited significantly shorter telomeres compared to the control group, and a significant correlation was found between telomere length and oxidative DNA damage. Using the PIXE method on urine samples, significantly higher concentrations of sodium (Na), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K), iron (Fe), zinc (Zn), and bromine (Br) were observed in the exposed group compared to the control group. Furthermore, men showed shorter telomeres, greater DNA damage, and higher concentrations of nickel (Ni), calcium (Ca), and chromium (Cr) compared to exposed women. Additionally, the study characterized the particles released into the environment through GC–MS analysis, identifying several compounds, including polycyclic aromatic hydrocarbons (PAHs) such as fluoranthene, naphthalene, anthracene, 7H-benzo[c]fluorene, phenanthrene, pyrene, benz[a]anthracene, chrysene, and some alkyl derivatives. These findings underscore the significant health risks associated with exposure to coal mining dust, emphasizing the importance of further research and the implementation of regulatory measures to safeguard the health of individuals in affected populations. Graphic abstract
- 4 August 2023
- Published by Springer Nature in Environmental Geochemistry and Health
- Vol. 45 (10) , 7081-7097
Open AccessThe dangerous link between coal dust exposure and DNA damage: unraveling the role of some of the chemical agents and oxidative stress
Exposure to coal mining dust poses a substantial health hazard to individuals due to the complex mixture of components released during the extraction process. This study aimed to assess the oxidative potential of residual coal mining dust on human lymphocyte DNA and telomeres and to perform a chemical characterization of coal dust and urine samples. The study included 150 individuals exposed to coal dust for over ten years, along with 120 control individuals. The results revealed significantly higher levels of DNA damage in the exposed group, as indicated by the standard comet assay, and oxidative damage, as determined by the FPG-modified comet assay. Moreover, the exposed individuals exhibited significantly shorter telomeres compared to the control group, and a significant correlation was found between telomere length and oxidative DNA damage. Using the PIXE method on urine samples, significantly higher concentrations of sodium (Na), phosphorus (P), sulfur (S), chlorine (Cl), potassium (K), iron (Fe), zinc (Zn), and bromine (Br) were observed in the exposed group compared to the control group. Furthermore, men showed shorter telomeres, greater DNA damage, and higher concentrations of nickel (Ni), calcium (Ca), and chromium (Cr) compared to exposed women. Additionally, the study characterized the particles released into the environment through GC–MS analysis, identifying several compounds, including polycyclic aromatic hydrocarbons (PAHs) such as fluoranthene, naphthalene, anthracene, 7H-benzo[c]fluorene, phenanthrene, pyrene, benz[a]anthracene, chrysene, and some alkyl derivatives. These findings underscore the significant health risks associated with exposure to coal mining dust, emphasizing the importance of further research and the implementation of regulatory measures to safeguard the health of individuals in affected populations. Graphic abstract
- Open Access
- 24 March 2023
- Published by Elsevier in Environmental Research
- Vol. 227, 115773
Exposure to coal mining can lead to imbalanced levels of inorganic elements and DNA damage in individuals living near open-pit mining sites
- 24 March 2023
- Published by Elsevier in Environmental Research
- Vol. 227, 115773
Open AccessExposure to coal mining can lead to imbalanced levels of inorganic elements and DNA damage in individuals living near open-pit mining sites
- Open Access
- 4 March 2023
- Published by Springer Nature in Environmental Science and Pollution Research
- Vol. 30 (18) , 54095-54105
Analysis of the cytotoxic and genotoxic effects in a population chronically exposed to coal mining residues
During coal mining activities, many compounds are released into the environment that can negatively impact human health. Particulate matter, polycyclic aromatic hydrocarbons (PAHs), metals, and oxides are part of the complex mixture that can affect nearby populations. Therefore, we designed this study to evaluate the potential cytotoxic and genotoxic effects in individuals chronically exposed to coal residues from peripheral blood lymphocytes and buccal cells. We recruited 150 individuals who lived more than 20 years in La Loma-Colombia and 120 control individuals from the city of Barranquilla without a history of exposure to coal mining. In the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay, significant differences in the frequency of micronucleus (MN), nucleoplasmic bridge (NPB), nuclear bud (NBUD), and apoptotic cells (APOP) were observed between the two groups. In the buccal micronucleus cytome (BM-Cyt) assay, a significant formation of NBUD, karyorrhexis (KRX), karyolysis (KRL), condensed chromatin (CC), and binucleated (BN) cells was observed in the exposed group. Considering the characteristics of the study group, a significant correlation for CBMN-Cyt was found between NBUD and vitamin consumption, between MN or APOP and meat consumption, and between MN and age. Moreover, a significant correlation for BM-Cyt was found between KRL and vitamin consumption or age, and BN versus alcohol consumption. Using Raman spectroscopy, a significant increase in the concentration of DNA/RNA bases, creatinine, polysaccharides, and fatty acids was detected in the urine of individuals exposed to coal mining compared to the control group. These results contribute to the discussion on the effects of coal mining on nearby populations and the development of diseases due to chronic exposure to these residues.
- 4 March 2023
- Published by Springer Nature in Environmental Science and Pollution Research
- Vol. 30 (18) , 54095-54105
Open AccessAnalysis of the cytotoxic and genotoxic effects in a population chronically exposed to coal mining residues
During coal mining activities, many compounds are released into the environment that can negatively impact human health. Particulate matter, polycyclic aromatic hydrocarbons (PAHs), metals, and oxides are part of the complex mixture that can affect nearby populations. Therefore, we designed this study to evaluate the potential cytotoxic and genotoxic effects in individuals chronically exposed to coal residues from peripheral blood lymphocytes and buccal cells. We recruited 150 individuals who lived more than 20 years in La Loma-Colombia and 120 control individuals from the city of Barranquilla without a history of exposure to coal mining. In the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay, significant differences in the frequency of micronucleus (MN), nucleoplasmic bridge (NPB), nuclear bud (NBUD), and apoptotic cells (APOP) were observed between the two groups. In the buccal micronucleus cytome (BM-Cyt) assay, a significant formation of NBUD, karyorrhexis (KRX), karyolysis (KRL), condensed chromatin (CC), and binucleated (BN) cells was observed in the exposed group. Considering the characteristics of the study group, a significant correlation for CBMN-Cyt was found between NBUD and vitamin consumption, between MN or APOP and meat consumption, and between MN and age. Moreover, a significant correlation for BM-Cyt was found between KRL and vitamin consumption or age, and BN versus alcohol consumption. Using Raman spectroscopy, a significant increase in the concentration of DNA/RNA bases, creatinine, polysaccharides, and fatty acids was detected in the urine of individuals exposed to coal mining compared to the control group. These results contribute to the discussion on the effects of coal mining on nearby populations and the development of diseases due to chronic exposure to these residues.