title: Mitochondrial permeability and toxicity of diethylhexyl and monoethylhexyl phthalates on TK6 human lymphoblasts cells.
abstract: Phthalates are ubiquitous compounds used in the manufacturing industry. Some are known endocrine disruptors, acting as xenoestrogens, others induce reproductive toxicity and damage to DNA among other effects. Studies on apoptosis induction and mitochondrial damage capacity of phthalates on the immune system are limited. This study aims to determine cell viability inhibition and apoptosis induction of diethylhexyl phthalate (DEHP) and monoethylhexyl phthalate (MEHP) on the human TK6 lymphoblast cell line at concentrations found in the environment. Key hallmark events, such as mitochondrial membrane permeability, generation of reactive oxygen species (ROS) and activation of caspase 3 and 7 were measured. Concentrations that inhibit viability of 50% (IC50) of the cells were determined at 24, 48 and 72 h with doses ranging from 10 to 500 μM. Changes in mitochondrial membrane permeability, ROS generation and activation of caspases 3 and 7, were measured as part of the cell death mechanism. The IC50 at 24 h was approximately 250 μM for both phthalates; at 48 h were 234 and 196 μM for DEHP and MEHP, respectively and at 72 h IC50s were 100 and 80 μM for DEHP and MEHP, respectively. Overall the longer the time of exposure the lower the IC50's for both compounds. Both compounds affected mitochondrial membrane potential, promoted ROS generation and activated caspases 3 and 7. MEHP is more toxic, promotes higher level of ROS production and caspases activation. Our findings suggest that DEHP and MEHP have the capacity to induce apoptosis in cells of the immune system at concentrations found in the environment.
authors.affiliation: Universidad Metropolitana, School of Environmental Affairs, PO Box 21150, San Juan 00928-1150, Puerto Rico. bzayas@suagm.edu
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Rosado-Berrios
authors.forename: Christian
authors.initials: C
authors.lastname: Vélez
authors.forename: Beatriz
authors.initials: B
authors.lastname: Zayas
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D045744:Cell Line, Tumor; D004785:Environmental Pollutants / Q000633:toxicity*; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D010539:Permeability / Q000187:drug effects; D010795:Phthalic Acids / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects* / Q000502:physiology
chemical_list: D004785:Environmental Pollutants; D010795:Phthalic Acids; D017382:Reactive Oxygen Species; D053148:Caspase 3; D053179:Caspase 7