0

In Vitro Metabolism of Methiocarb and Carbaryl in Rats, and Its Effect on Their Estrogenic and Antiandrogenic Activities

Satoko Tange, Nariaki Fujimoto, Naoto Uramaru, Fung Fuh Wong, Kazumi Sugihara, Shigeru Ohta, Shigeyuki Kitamura

Environ Toxicol Pharmacol. 2016 Jan;41:289-97.

PMID: 26774076

Abstract:

In this work, we examined the metabolism of the carbamate insecticides methiocarb and carbaryl by rat liver microsomes and plasma, and its effect on their endocrine-disrupting activities. Methiocarb and carbaryl were not enzymatically hydrolyzed by rat liver microsomes, but were hydrolyzed by rat plasma, mainly to methylthio-3,5-xylenol (MX) and 1-naphthol, respectively. When methiocarb was incubated with rat liver microsomes in the presence of NADPH, methiocarb sulfoxide was formed. The hydrolysis product, MX, was also oxidized to the sulfoxide, 3,5-dimethyl-4-(methylsulfinyl)phenol (SP), by rat liver microsomes in the presence of NADPH. These oxidase activities were catalyzed by cytochrome P450 and flavin-containing monooxygenase. Methiocarb and carbaryl both exhibited estrogen receptor α (ERα) and ERβ agonistic activity. MX and 1-naphthol showed similar activities, but methiocarb sulfoxide and SP showed markedly decreased activities. On the other hand, methiocarb and carbaryl exhibited potent antiandrogenic activity in the concentration range of 1×10(-6)-3×10(-5) M. Their hydrolysis products, MX, and 1-naphthol also showed high activity, equivalent to that of flutamide. However, methiocarb sulfoxide and SP showed relatively low activity. Thus, hydrolysis of methiocarb and carbaryl and oxidation of methiocarb to the sulfoxide markedly modified the estrogenic and antiandrogenic activities of methiocarb and carbaryl.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP2635101 Methiocarb sulfoxide Methiocarb sulfoxide 2635-10-1 Price
qrcode