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Hydroxyl radical generating activity of hydrous but not calcined kaolin is prevented by surface modification with dipalmitoyl lecithin.

Authors
Baser-ME; Kennedy-TP; Dodson-R; Rao-NV; Rawlings-W Jr.; Hoidal-JR
Source
J Toxicol Environ Health 1990 Jan; 29(1):99-108
NIOSHTIC No.
00195118
Abstract
The effect of surface modification with dipalmitoyl-lecithin (DPL) on the radical generating activity of hydrous and calcined kaolin (1332587) was determined in a chemical system that measured hydroxyl radicals ((-)OH) as the evolution of methane (CH4) from dimethyl- sulfoxide (67685) (DMSO). Both hydrous and calcined kaolin exhibited marked activity as catalysts for producing (-)OH from hydrogen-peroxide (H2O2). In the presence of a reducing agent and 10 millimolar H2O2, hydrous and calcined kaolin generated mean CH4 concentrations of 1634 and 1395 parts per million (ppm), respectively. Surface modification with DPL, the lipid of pulmonary surfactant, blocked generation of (-)OH in hydrous kaolin (38ppm CH4) but not in calcined kaolin (875ppm CH4). Catalytic activity was prevented by preincubating kaolin with deferoxamine. The authors conclude that the catalytic activity of kaolin for producing (-)OH from H2O2 may be important in the pathogenesis of kaolin toxicity. Calcined kaolin may be more toxic than hydrous kaolin because the calcined form is resistant to surface modification by lipids of pulmonary surfactant.
Keywords
NIOSH-Author; Toxicology; Aluminum-compounds; Free-radical-generation; Chemical-reactions; Chemical-properties; Toxic-materials; Lung-disorders; Lung-irritants
CODEN
JTEHD6
CAS No.
1332-58-7; 67-68-5
Publication Date
19900101
Document Type
Journal Article
Funding Amount
574424
Funding Type
Grant
Fiscal Year
1990
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-02264
Issue of Publication
1
ISSN
0098-4108
Priority Area
Pulmonary-system-disorders
Source Name
Journal of Toxicology and Environmental Health
State
TN
Performing Organization
University of Tenn Center Health Scien, Memphis, Tennessee
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