Metabolism of two new benzodiazepine-type anti-leishmanial agents in rat hepatocytes and hepatic microsomes and their interaction with glutathione in macrophages.
OBJECTIVE
To measure the metabolism and toxicity of 7-chloro-4-(cyclohexylmethyl)-1-methyl-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione (BNZ-1) and 4-cyclohexylmethyl-1-methyl-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione (BNZ-2), two new benzodiazepine analogues found to be effective against Leishmania amastigotes in vitro.


METHODS
The metabolism of BNZ-1 and -2 was investigated in isolated rat hepatocytes and rat liver microsomes. The toxicity of the compounds was assessed in a murine macrophage cell line by determining cell viability and reduced glutathione (GSH) content. The metabolism and toxicity of flurazepam was assessed for comparison.


RESULTS
BNZ-1 and BNZ-2 underwent similar metabolic transformations by the liver systems, forming N-demethylated and hydroxylated metabolites, with subsequent O-glucuronidation. Flurazepam and both analogue compounds depleted macrophage GSH levels without affecting cell viability at the concentrations used (up to 100 microM), but only flurazepam inhibited glutathione reductase activity, indicating that it is acting by a different mechanism.


CONCLUSIONS
The exact mechanism responsible for GSH depletion is unknown at present. Further experiments are needed to fully understand the effects of BNZs on the parasite GSH analogue, trypanothione, which may be a direct or indirect target for these agents. Pharmacokinetic evaluation of these compounds is required to further progress their development as potential new treatments for leishmaniasis.
Thi
M Dao Duong
MD
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK.
Grant
M Helen
MH
Mullen
Alexander B
AB
Tettey
Justice N A
JN
MacKay
Simon P
SP
Clark
Rachel L
RL
D000818:Animals; D001569:Benzodiazepines / Q000378:metabolism / Q000633:toxicity*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005479:Flurazepam / Q000378:metabolism / Q000633:toxicity; D005978:Glutathione / Q000187:drug effects* / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018675:Toxicity Tests; D014344:Trypanocidal Agents / Q000378:metabolism / Q000633:toxicity*
C539667:4-cyclohexylmethyl-1-methyl-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione; C539666:7-chloro-4-(cyclohexylmethyl)-1-methyl-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione; D014344:Trypanocidal Agents; D001569:Benzodiazepines; D005978:Glutathione; D005479:Flurazepam