TY - JOUR
T1 - Hydrolysis of di-n-butyl phthalate, butylbenzyl phthalate and di(2-ethylhexyl) phthalate in human liver microsomes
AU - Hanioka, Nobumitsu
AU - Takahara, Yuusuke
AU - Takahara, Yuka
AU - Tanaka-Kagawa, Toshiko
AU - Jinno, Hideto
AU - Narimatsu, Shizuo
N1 - Funding Information:
This work was supported in part by Health and Labor Sciences Research Grants from the Ministry of Health and Labor and Welfare of Japan.
PY - 2012/11
Y1 - 2012/11
N2 - Diester phthalates are industrial chemicals used primarily as plasticizers to import flexibility to polyvinylchloride plastics. In this study, we examined the hydrolysis of di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) in human liver microsomes. These diester phthalates were hydrolyzed to monoester phthalates (mono-n-butyl phthalate (MBP) from DBP, mono-n-butyl phthalate (MBP) and monobenzyl phthalate (MBzP) from BBzP, and mono(2-ethylhexyl) phthalate (MEHP)) by human liver microsomes. DBP, BBzP and DEHP hydrolysis showed sigmoidal kinetics in V-[S] plots, and the Hill coefficient (n) ranged 1.37-1.96. The S50, Vmax and CLmax values for DBP hydrolysis to MBP were 99.7μM, 17.2nmolmin-1mg-1 protein and 85.6μLmin-1mg-1 protein, respectively. In BBzP hydrolysis, the values of S50 (71.7μM), Vmax (13.0nmolmin-1mg-1 protein) and CLmax (91.3μLmin-1mg-1 protein) for MBzP formation were comparable to those of DBP hydrolysis. Although the S50 value for MBP formation was comparable to that of MBzP formation, the Vmax and CLmax values were markedly lower (<3%) than those for MBzP formation. The S50, Vmax and CLmax values for DEHP hydrolysis were 8.40μM, 0.43nmolmin-1mg-1 protein and 27.5μLmin-1mg-1 protein, respectively. The S50 value was about 10% of DBP and BBzP hydrolysis, and the Vmax value was also markedly lower (<3%) than those for DBP hydrolysis and MBzP formation for BBzP hydrolysis. The ranking order of CLmax values for monoester phthalate formation in DBP, BBzP and DEHP hydrolysis was BBzP to MBzP≥DBP to MBP>DEHP to MEHP>BBzP to MBP. These findings suggest that the hydrolysis activities of diester phthalates by human liver microsomes depend on the chemical structure, and that the metabolism profile may relate to diester phthalate toxicities, such as hormone disruption and reproductive effects.
AB - Diester phthalates are industrial chemicals used primarily as plasticizers to import flexibility to polyvinylchloride plastics. In this study, we examined the hydrolysis of di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) in human liver microsomes. These diester phthalates were hydrolyzed to monoester phthalates (mono-n-butyl phthalate (MBP) from DBP, mono-n-butyl phthalate (MBP) and monobenzyl phthalate (MBzP) from BBzP, and mono(2-ethylhexyl) phthalate (MEHP)) by human liver microsomes. DBP, BBzP and DEHP hydrolysis showed sigmoidal kinetics in V-[S] plots, and the Hill coefficient (n) ranged 1.37-1.96. The S50, Vmax and CLmax values for DBP hydrolysis to MBP were 99.7μM, 17.2nmolmin-1mg-1 protein and 85.6μLmin-1mg-1 protein, respectively. In BBzP hydrolysis, the values of S50 (71.7μM), Vmax (13.0nmolmin-1mg-1 protein) and CLmax (91.3μLmin-1mg-1 protein) for MBzP formation were comparable to those of DBP hydrolysis. Although the S50 value for MBP formation was comparable to that of MBzP formation, the Vmax and CLmax values were markedly lower (<3%) than those for MBzP formation. The S50, Vmax and CLmax values for DEHP hydrolysis were 8.40μM, 0.43nmolmin-1mg-1 protein and 27.5μLmin-1mg-1 protein, respectively. The S50 value was about 10% of DBP and BBzP hydrolysis, and the Vmax value was also markedly lower (<3%) than those for DBP hydrolysis and MBzP formation for BBzP hydrolysis. The ranking order of CLmax values for monoester phthalate formation in DBP, BBzP and DEHP hydrolysis was BBzP to MBzP≥DBP to MBP>DEHP to MEHP>BBzP to MBP. These findings suggest that the hydrolysis activities of diester phthalates by human liver microsomes depend on the chemical structure, and that the metabolism profile may relate to diester phthalate toxicities, such as hormone disruption and reproductive effects.
KW - Butylbenzyl phthalate (BBzP)
KW - Di(2-ethylhexyl) phthalate (DEHP)
KW - Di-n-butyl phthalate (DBP)
KW - Human liver microsomes
KW - Hydrolysis
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U2 - 10.1016/j.chemosphere.2012.05.095
DO - 10.1016/j.chemosphere.2012.05.095
M3 - Article
C2 - 22739543
AN - SCOPUS:84865739029
VL - 89
SP - 1112
EP - 1117
JO - Chemosphere
JF - Chemosphere
SN - 0045-6535
IS - 9
ER -