[Metabolites of R, S-1-(2-methoxyphenyl)-4-[3-(naphtha-1-yl-oxy)-2-hydroxypropyl]-piperazin in rat plasma].
OBJECTIVE
To study the metabolites of R, S-1-(2-methoxypheyl)-4-[3-(naphthal-yl-oxy)-2-hydroxypropyl] -piperazine, (naftopidil, NAF), a novel antihypertensive drug in rat plasma.


METHODS
The rat plasma samples were analyzed by LC/MS after oral administration of NAF. According to MS relativity of metabolites and parent compound (NAF) and metabolic rule of compound with similar structure, the structure of potential metabolites were postulated. Phase I metabolites were identified by HPLC/MS and by comparison with authentic standards, phase II conjugates were indirectly identified with beta-D-glucuronidase in presence or absence of glucuronidase selective inhibitor D-saccharric acid beta-1,4-Lactone.


RESULTS
Phase I metabolites desmethyl-naftopidil (DMN), (phenyl) hydroxynaftopidil (PHN), (naphthyl) -hydroxy-naftopidil (NHN) were separated and identified in rat plasma by comparison with reference substances, phase II conjugates, NAF and NHN glucuronide conjugates were separated and tentatively identified by hydrolysis with glucuronidase, the aglycones, NAF and NHN, were identified in rat plasma.


CONCLUSIONS
The major metabolic pathway of NAF in rat plasma should be the hydroxylation of the phenyl or nephthyl moiety of NAF and demethylation of NAF. Therefore, (naphthyl) hydroxyl-metabolite and NAF followed by conjugation with beta-glueuronic acid.
Li
Li
L
Key Lab of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences, Guiyang 550002, China.
Zhou
Xin
X
Yuan
Mu
M
Zhou
Hong
H
Wang
Dao-Ping
DP