title: Anti-inflammatory, anti-bacterial, and cytotoxic activity of fibrous clays.
abstract: Produced worldwide at 1.2m tons per year, fibrous clays are used in the production of pet litter, animal feed stuff to roof parcels, construction and rheological additives, and other applications needing to replace long-fiber length asbestos. To the authors' knowledge, however, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the anti-inflammatory, anti-bacterial, and cytotoxic activity by sepiolite (Vallecas, Spain) and palygorskite (Torrejon El Rubio, Spain). The anti-inflammatory activity was determined using the 12-O-tetradecanoylphorbol-13-acetate (TPA) and myeloperoxidase (MPO) methods. Histological cuts were obtained for quantifying leukocytes found in the epidermis. Palygorkite and sepiolite caused edema inhibition and migration of neutrophils ca. 68.64 and 45.54%, and 80 and 65%, respectively. Fibrous clays yielded high rates of infiltration, explained by cleavage of polysomes and exposure of silanol groups. Also, fibrous clays showed high inhibition of myeloperoxidase contents shortly after exposure, but decreased sharply afterwards. In contrast, tubular clays caused an increasing inhibition of myeloperoxidase with time. Thus, clay structure restricted the kinetics and mechanism of myeloperoxidase inhibition. Fibrous clays were screened in vitro against human cancer cell lines. Cytotoxicity was determined using the protein-binding dye sulforhodamine B (SRB). Exposing cancer human cells to sepiolite or palygorskite showed growth inhibition varying with cell line. This study shows that fibrous clays served as an effective anti-inflammatory, limited by chemical transfer and cellular-level signals responding exclusively to an early exposure to clay, and cell viability decreasing significantly only after exposure to high concentrations of sepiolite.
authors.affiliation: Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana, Unidad Cuajimalpa, México, Mexico; Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA; NASA Astrobiology Institute, Mountain View, CA, USA. Electronic address: jcervini@correo.cua.uam.mx.
authors.forename: Javiera
authors.initials: J
authors.lastname: Cervini-Silva
authors.affiliation: Laboratorio de Pruebas Biológicas, Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, Mexico.
authors.forename: Antonio-
authors.initials: A
authors.lastname: Nieto-Camacho
authors.affiliation: Laboratorio de Pruebas Biológicas, Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, Mexico.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Ramírez-Apan
authors.affiliation: Laboratorio de Resonancia Paramagnética Electrónica, Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, Mexico.
authors.forename: Virginia
authors.initials: V
authors.lastname: Gómez-Vidales
authors.affiliation: Direccion de Investigación y Posgrado, Instituto Mexicano del Petróleo, Mexico.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Palacios
authors.affiliation: Direccion de Investigación y Posgrado, Instituto Mexicano del Petróleo, Mexico.
authors.forename: Ascención
authors.initials: A
authors.lastname: Montoya
authors.affiliation: Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana, Unidad Cuajimalpa, México, Mexico.
authors.forename: Elba
authors.initials: E
authors.lastname: Ronquillo de Jesús
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D000863:Antacids / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D000931:Antidotes / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D000077215:Clay; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D007700:Kinetics; D008264:Macrophages / Q000166:cytology / Q000187:drug effects; D017616:Magnesium Compounds / Q000494:pharmacology*; D017633:Magnesium Silicates / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017655:Silicon Compounds / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity
chemical_list: D000538:Aluminum Silicates; D000863:Antacids; D000900:Anti-Bacterial Agents; D000893:Anti-Inflammatory Agents; D000931:Antidotes; D000970:Antineoplastic Agents; D017616:Magnesium Compounds; D017633:Magnesium Silicates; D017655:Silicon Compounds; C001671:magnesium trisilicate; D009195:Peroxidase; D013755:Tetradecanoylphorbol Acetate; D000077215:Clay; C026325:attapulgite
keywords: Early anti-inflammatory response; Frequency of inversion sites; Silanol groups