Investigation of Vasodilatory Substances in Diesel Exhaust Particles (DEP): Isolation and Identification of Nitrophenol Derivatives

Vasodilatory compounds in the weak acidic fraction of a benzene extract of diesel exhaust particles (DEP) were fractionated by column chromatography through silica gel, and the chemical structures of these compounds were analyzed using GC-MS and 1H-NMR. The compounds in DEP that cause vasodilation — 3- and 4-nitrophenol, 2-methyl-4-nitrophenol, 3-methy-4-nitrophenol, and 4-nitro-3-phenylphenol — were isolated and identified. All five of these nitrophenols had vasodilatory activities (10-4 to 10-6 M) in rat thoracic artery assays, and 4-nitro-3-phenylphenol was the most potent vasodilator among these compounds. In addition, nine other alkylnitrophenols were isolated from the benzene extract of DEP and characterized.