STUDIES ON THE EFFECTS OF DIESEL EXHAUST PARTICLES ON HUMAN HEALTH

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Diesel cars exhaust 30-100 times more particles (DEP) than do gasoline engine cars. DEP is one of the most important air pollution substances, especially, in the big city. Previously, the authors found that DEP could react with oxygen to produce superoxide anion radicals (O_2^-・) in vitro without any biological activating systems. In order to know, furthermore, the mechanism of biological effects of DEP on human health related to reactive oxygen intermediates, we aimed to 1) isolate and identify the compounds responsible for generation of O_2^-・in DEP,and 2) estimate the inhibitory activity of DEP components on catalase activity which is the scavenger of reactive oxygen intermediate. And furthermore, the effects of DEP on the complement activity was evaluated.1) DEP were extracted serially, with hexane, benzene, dichloromethane, and methanol, and it was found that O_2^-・generation substances were distributed to each 4 extracts indicating that heterogeneous compounds in DEP could generate O_2^-・Superoxide anion producing activity of these extracts were increased seriously by reduction with NADPH and P450 reductase. With column chromatography and HPLC,a O_2^-・producing substance was isolated and the chemical structure was identified as 1-methyl-3-hydroxyphthalate. 2) Buffer extract of DEP could inhibit the activity of catalase, in the presence of chloride ion. Thus, DEP could injury human health by producing reactive oxygen intermediates (ROI), and inhibition of degradation of ROI.Furthermore, DEP extract could activate the alternative pathway of human complement system.From these studies, it was found that DEP inhaled and deposed in trachea could injury cells and induce pulmonary disease with some different mechanisms.