Isolation and identification of new vasodilative substances in diesel exhaust particles.
OBJECTIVE
We recently developed a new isolation method for diesel exhaust particles (DEP), involving successive extraction with H(2)O, sodium bicarbonate, and sodium hydroxide, in which the sodium hydroxide extract was found to consist of phenolic components. Analysis of the extract revealed that vasodilative-active nitrophenols are in DEP in significantly higher concentrations than those estimated by an earlier method involving a combination of solvent extraction and repeated chromatography. These findings indicated that our new procedure offers a simple, efficient, and reliable method for the isolation and identification of bioactive substances in DEP. This encouraged us to extend our work toward investigating new vasodilatory substances in the sodium bicarbonate extract.


METHODS
DEP were collected from the exhaust of a 4JB1-type engine (ISUZU Automobile Co., Tokyo, Japan). GC-MS analysis was performed with a GCMS-QP2010 instrument (Shimadzu, Kyoto, Japan).


RESULTS
DEP dissolved in 1-butanol was successively extracted with water, sodium bicarbonate, and then aqueous sodium hydroxide. The sodium bicarbonate extract was neutralized and the resulting mixture of acidic components was subjected to reverse-phase (RP) column chromatography followed by RP-HPLC with fractions assayed for vasodilative activity. This led to the identification of terephthalic acid, p-hydroxybenzoic acid, isophthalic acid, phthalic acid, 3-hydroxy-4-nitrobenzoic acid, 4-hydroxy-3-nitrophenol, and 1,4,5-naphthalene tricarboxylic acid as components of DEP.


CONCLUSIONS
The sodium bicarbonate extract was rich in aromatic carboxylic acid components. Repeated reverse-phase chromatography resulted in the successful isolation of several acidic substances including the new vasodilative materials, 4-hydroxy-3-nitrobenzoic acid, and 3-hydroxy-4-nitrobenzoic acid.


CONCLUSIONS
Our new fractionation method for DEP has made possible the isolation of new vasodilative compounds from the sodium bicarbonate extract.
Seki
Koh-ichi
K
Central Institute of Isotope Science, Graduate School of Medicine, Hokkaido University, Sapporo, 060-0815, Japan. seki@ric.hokudai.ac.jp
Noya
Yoichi
Y
Mikami
Yusuke
Y
Taneda
Shinji
S
Suzuki
Akira K
AK
Kuge
Yuji
Y
Ohkura
Kazue
K
D000393:Air Pollutants / Q000737:chemistry / Q000302:isolation & purification*; D000818:Animals; D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D008297:Male; D009596:Nitrophenols / Q000302:isolation & purification*; D052638:Particulate Matter / Q000737:chemistry / Q000302:isolation & purification*; D010795:Phthalic Acids / Q000737:chemistry / Q000302:isolation & purification; D051381:Rats; D017693:Sodium Bicarbonate / Q000737:chemistry; D014665:Vasodilator Agents / Q000737:chemistry / Q000302:isolation & purification*; D001335:Vehicle Emissions / Q000032:analysis*
D000393:Air Pollutants; D009596:Nitrophenols; D052638:Particulate Matter; D010795:Phthalic Acids; D014665:Vasodilator Agents; D001335:Vehicle Emissions; C032279:phthalic acid; D017693:Sodium Bicarbonate