RT Journal Article
SR Electronic
T1 Xanthates: Metabolism by Flavoprotein-Containing Monooxygenases and Antimycobacterial Activity
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1091
OP 1095
DO 10.1124/dmd.118.081984
VO 46
IS 8
A1 Stanislav G. Yanev
A1 Tsveta D. Stoyanova
A1 Violeta V. Valcheva
A1 Paul R. Ortiz de Montellano
YR 2018
UL http://dmd.aspetjournals.org/content/46/8/1091.abstract
AB Ethionamide (ETH) plays a central role in the treatment of tuberculosis in patients resistant to the first-line drugs. The ETH, thioamide, and thiourea class of antituberculosis agents are prodrugs that are oxidatively converted to their active S-oxides by the mycobacterial flavin-dependent monooxygenase (EtaA) of Mycobacterium tuberculosis, thus initiating the chain of reactions that result in inhibition of mycolic acid biosynthesis and cell lysis. As part of a search for new lead candidates, we report here that several xanthates are oxidized by purified EtaA to S-oxide metabolites (perxanthates), which are implicated in the antimycobacterial activity of these compounds. This process, which is analogous to that responsible for activation of ETH, is also catalyzed by human flavoprotein monooxygenase 3. EtaA was not inhibited in a time-dependent manner during the reaction. Xanthates with longer alkyl chains were oxidized more efficiently. EtaA oxidized octyl-xanthate (Km = 5 µM; Vmax = 1.023 nmolP/min; kcat = 5.2 molP/min/molE) more efficiently than ETH (194 µM; 1.46 nmolP/min; 7.73 nmolP/min/molE, respectively). Furthermore, the in vitro antimycobacterial activity of four xanthates against M. tuberculosis H37Hv was higher (minimum inhibitory concentration of around 1 µM) than that of ETH (12 µM).