| Description |
TLK117, the active metabolite of TLK199, selective inhibits Glutathione S-transferase P1–1 (GSTP1-1) with a Ki of 0.4 μM for GSTP. TLK117 also competitively inhibits glyoxalase I with a Ki of 0.56 μM.
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| Related Catalog |
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| Target |
Ki: 0.4 μM[1], 0.56 μM (glyoxalase I)[2]
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| In Vitro |
TLK117 is the most specific GSTP inhibitor to date, with a binding affinity greater than GSH itself and a selectivity for GSTP over 50-fold greater than the GSTM and GSTA classes (Ki=0.4 μM)[1]. TER 117 is developed as a GST P1-1 isoenzyme inhibitor to circumvent the indicated contribution of GST P1-1 to drug resistance of tumor cells. To facilitate the cellular uptake of TER 117, it is delivered as a diethyl ester (TER 117 DEE, also called TER 199). TER 117 is found to be a competitive inhibitor of both GST P1-1 and glyoxalase I[2].
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| In Vivo |
Oropharyngeal administration of the GSTP inhibitor, TLK117, at a time when fibrosis is already apparent, attenuated bleomycin- and AdTGFβ-induced remodeling, α-SMA, caspase activation, FAS S-glutathionylation, and total protein S-glutathionylation. Four hours after administration of 50 mg/kg TLK117, GSTP activity is strongly decreased and remains decreased by about 60% for at least 24 hours[2].
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| Kinase Assay |
The potency of TER 117 in the inhibition of GST P1-1/Ile-105 and GST P1-1/Val-105 is determined by means of GSH competition experiments using 1 μM TER 117 and three different fixed concentrations of GSH: 0.2, 0.6, and 2.0 mM. The concentration of the second substrate, 1-chloro-2,4-dinitrobenzene (CDNB) ranged between 0.15 and 1.8 mM. In addition, the inhibitor is tested at different concentrations, 0 to 8 μM, at a CDNB concentration of 1 mM and the above GSH concentrations. Initial velocities are determined spectrophotometrically at 30°C. The conjugation reaction between GSH and CDNB is monitored at 340 nm in 1 mL of 0.1 M sodium phosphate, pH 7.0[2].
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| Animal Admin |
Mice[1] TLK117 is administered oropharyngeally at a dose of 50 mg/kg in a 0.375 M Tris-HCl solution, pH =7.4, with 0.02% DMSO. This Tris-HCl/DMSO solution is used as a vehicle control. Treatments are performed once every 3 days from day 14 to day 26 in both >bleomycin and AdTGFβ models
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| References |
[1]. The human glutathione transferase P1-1 specific inhibitor TER 117 designed for overcomingcytostatic-drug resistance is also a strong inhibitor of glyoxalase I. Mol Pharmacol. 2000 Mar;57(3):619-24. [2]. McMillan DH, et al. Attenuation of lung fibrosis in mice with a clinically relevant inhibitor of glutathione-S-transferase π. JCI Insight. 2016 Jun 2;1(8). pii: e85717.
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