Characterization of phenoxyacetic acid compounds in inhibition of human glutathione-S-transferase Mu

Abstract

Objective To design and synthesize 4 phenoxyacetic acid compounds, characterize their inhibitory potencies on human glutathione-S-transferase Mu (glutathione-S-transferase Mu, GSTM) by different methods, and investigate the structure-activity relationship between phenoxyacetic acid compounds and GSTM. Methods Four phenoxyacetic acid compounds were designed and synthesized, and they are ethyl 2-(4-acryloylphenoxy)acetate (Ⅰa) and N, N'-(butane-1, 4-diyl)-bis-(4-acryloyl phenoxyacetic amide) (Ⅱa) containing α, β-unsaturated ketone structure, and ethyl 2-(4-propionylphenoxy)acetate (Ⅰb), N, N'-(butane-1, 4-diyl)-bis-(4-propionyl phenoxyacetic amide) (Ⅱb) not containing α, β-unsaturated ketone structure. They were characterized by the half-maximal inhibitory concentration (IC50) and apparent inhibition constant (Ki) using initial velocity method, and the dissociation constants (Kd) for GSTM utilizing fluorescence analysis. Results Ⅰa and Ⅱa contained α, β-unsaturated ketone structure that undergoes electrophilic addition reaction with GSH. After incubation with enzyme and GSH, Ⅰa and Ⅱa generated products in situ, with a IC50 value of 67.00±6.00 and 0.10±0.02 μmol/L for GSTM respectively (n=2). Ⅰb and Ⅱb without α, β -unsaturated ketone structures had no inhibitory potencies for GSTM. The Ki of Ⅰa against GSH was 19.9±1.6 μmol/L, and the Ki against CDNB was 9.1±0.7 μmol/L (n=3). The Ki of Ⅱa against GSH was 0.063±0.005 μmol/L, and against CDNB was 0.079±0.006 μmol/L (n=3). The Ki of Ⅱa was lower than that ofⅠa (P 0.05). The Kd of Ⅱa was lower than that of Ⅰa, and the Kd of Ⅱb was lower than that of Ⅰb (P < 0.05). Conclusion α, β-unsaturated ketone structure is the essential functional group of phenoxyacetic acid compounds for inhibition on GSTM. Comparing with monovalent Ⅰa and Ⅰb, divalent Ⅱa and Ⅱb have higher affinity for GSTM. The product of Ⅱa has inhibitory potency significantly higher than that of Ⅰa.

Keywords

• phenoxyacetic acid compound
• glutathione-s-transferase mu
• inhibitory property
• characterization