Identification of estrogenic/anti-estrogenic compounds in diesel exhaust particulate extract.

Keiko Noguchi, Akira Toriba, Sang Woon Chung, Ryoichi Kizu, Kazuichi Hayakawa

Index: Biomed. Chromatogr. 21(11) , 1135-42, (2007)

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Abstract

Diesel exhaust particulate extract (DEPE) was obtained from diesel exhaust particulates with Soxhlet extraction using dichloromethane. After separating DEPE into 11 fractions by liquid-liquid extraction, the neutral fraction (N) showed anti-estrogenic activity and the weak acid (phenol) fraction (WA(P)) showed estrogenic and anti-estrogenic activities by a yeast two-hybrid assay system expressing human estrogen receptor alpha. Both fractions were thoroughly fractionated by silica gel column chromatography and reversed-phase HPLC. In the WA(P) fraction, 3-methyl-4-nitrophenol and 2,6-dimethyl-4-nitrophenol were identified by LC-MS/MS as estrogenic compounds. This is the first study to identify 2,6-dimethyl-4-nitrophenol in DEPE and the first study to show that it is an estrogenic compound. In the N fraction, 1-hydroxypyrene was also identified by LC-MS/MS as an anti-estrogenic compound.Copyright (c) 2007 John Wiley & Sons, Ltd.