In Vitro Inhibition of Glutathione-S-Transferase by Some Plant Extracts and Chemical Compounds

Abstract Glutathione-S-transferase (GST, EC 2.5.1.18) is a detoxification enzyme which belongs to the transferase enzyme family. This enzyme is found in many prokaryotic and all eukaryotic cells. GST catalyzes conjugation of reduced glutathione with exogen, mutagens, etc. The relation between increased GST activities and cancer cases have directed researchers to investigate the possible inhibition of this enzyme. For this reason, phytochemicals are at the center of this research due to their useful properties. In this study, we aimed to investigate the potentials of plant extracts and chemical compounds to inhibit GST. GST inhibitory effects of various samples were determined according to Habig et al. method. The inhibition assays were determined spectrophotometrically at 340 nm as considering absorbance alteration between zero and third minutes. 1‑Chloro-2,4-dinitro benzene was used as substrate. In our study, aqueous plant extracts were prepared. Among the plant extracts, chard (IC50 = 17.01 ± 1.16 mg/mL), spinach (IC50 = 24.93 ± 2.86 mg/mL), and lemon (IC50 = 29.32 ± 2.98 mg/mL) showed the best inhibition. Among the chemical substances, bivalent compounds of copper (IC50 = 5.72 ± 0.13 mM), cadmium (IC50 = 5.86 ± 0.55 mM), zinc (IC50 = 25.68 ± 1.62 mM), and vitamin B6 (IC50 = 16.26 ± 2.72 mM) were observed as the best inhibitory chemical compounds. When we consider the phytochemical screening of plant extracts and the structures of chemical compounds, we can hypothesize that they could be new targets in cancer treatments as targets for GST inhibition.