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Pregnancy-Related Proteins Detected by Their Biological Activities
Published in Gábor N. Than, Hans Bohn, Dénes G. Szabó, Advances in Pregnancy-Related Protein Research, 2020
Glutathione S-transferase acts as a detoxicating enzyme for electrophilic compounds. It promotes the first step in the synthesis of mercapturic acid by catalyzing the conjugation of glutathione with several electrophilic compounds.101 Its activity is very high in early placentas. γ-Glutamyl transpeptidase, which catalyzes the second step in the biosynthesis of mercapturic acid by metabolizing glutathione conjugates formed by glutathione S-transferase, reaches its peak in specific activity by the 8th week of pregnancy. The absence of these enzymes from amniotic fluid and their highest activity during early pregnancy seem to indicate a protective mechanism for the fetus during its organogenesis phase when it is at its most vulnerable.66
Overview of the Biotransformation of Antiepileptic Drugs
Published in Carl L. Faingold, Gerhard H. Fromm, Drugs for Control of Epilepsy:, 2019
Glutathione Reactions. Glutathione conjugation is most important for the detoxification of several reactive metabolites, e.g., arene oxides, formed by phase I reactions. Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. Conjugation of drug metabolites is with the SH-group in cysteine. Glutathione interactions are catalyzed often by glutathione-S-transferase. However, glutathione may react nonenzymatically with some drug molecules, because transfer of glutathione does not require a high-energy activation as does glucuronic acid. Glutathione-S-transferase exists in many forms and is inducible by many xenobiotics. The enzyme is located in the cytosol of hepatic cells.
Inhibition of Colon Carcinogenesis*
Published in Herman Autrup, Gary M. Williams, Experimental Colon Carcinogenesis, 2019
Another important enzyme, glutathione S-transferase, is stimulated by many inhibitors of carcinogenesis.31,32 With respect to colon carcinogenesis, some inhibitors, butylated hydroxy toluene and disulfiram, have been found to enhance glutathione S-transferase activity. One mechanism of inhibition by these compounds is possibly related to the role of the transferase in carcinogen detoxification reactions catalyzing the binding of electrophiles to glutathione.33,34
The effects of REG4 expression on chemoresistance of ovarian cancer
Published in Journal of Obstetrics and Gynaecology, 2022
Li-Wei Xiang, Hang Xue, Min-Wen Ha, Da-Yong Yu, Li-Jun Xiao, Hua-Chuan Zheng
In addition, we found that the expression of GST-π, survivin, and Bcl-2 in REG4-overexpressing CAOV3 cells treated with cisplatin and paclitaxel were up-regulated compared with mock-transfected cells. Glutathione S-transferases are a family of isoenzymes that detoxify electrophiles by conjugation to thiol-reduced glutathione. Therefore, they are essential to protect cells from toxins (drugs, pesticides, carcinogens) and oxidative stress (Chatterjee and Gupta 2018). Glutathione S-transferases in human cells can be divided into three subclasses: alkaline (α), neutral (μ), and acidic (π); GST-π is the most closely related to drug resistance in tumours. The main function of GST is to catalyse the combination of glutathione with chemical drugs, thereby reducing their cytotoxic effect (Matsui et al. 2020). Therefore, REG4 may also increase the expression of GST-π and Bcl-2 allowing ovarian cancer cells to become resistant to cisplatin and paclitaxel.
Azithromycin effects on the European sea bass (Dicentrarchus labrax) early life stages following acute and chronic exposure: Laboratory bioassays
Published in Drug and Chemical Toxicology, 2022
Lazhar Mhadhbi, Tahani El Ayari, Meriam Tir, Dorra Kadri
Malondialdehyde (MDA) a biomarker of lipid peroxidation was measured by thiobarbituric acid reactive substances (TBARS) assay at 535 nm as described in Buege and Aust (1978) and Gutteridge and Halliwell (1990). The concentration of MDA was expressed in the units of µmol of MDA per g of fresh weight tissue. The activity of Glutathione S-transferase (GST) was determined following the method described by Habig et al. (1974), by measuring the conjugation of 1-chloro-2, 4-dinitrobenzene with reduced glutathione (GSH) at 340 nm. The specific activity was expressed as µmol/min/mg of hydrolyzed substrate relative to the total protein content. The catalase activity was determined by a spectrophotometrical measurement of H2O2 at 240 nm as described by Aebi (1984). The specific activity was expressed as μmol of decomposed H2O2 per min per mg of protein. The AChE activity was measured using a spectrophotometric method (Ellman et al. 1961). We used acetylcholine as substrate; the enzyme activity was expressed in µmol/min/mg, absorbance was read by spectrophotometer at 405 nm.
The effect of co-administration of berberine, resveratrol, and glibenclamide on xenobiotic metabolizing enzyme activities in diabetic rat liver
Published in Drug and Chemical Toxicology, 2022
Azra Bozcaarmutlu, Canan Sapmaz, Ömer Bozdoğan, Aysel Kükner, Leyla Kılınç, Salih Tunç Kaya, Oğulcan Talat Özarslan, Didem Ekşioğlu
Co-administration of R+B in the diabetic rats decreased CYP2B-associated PROD activity to the non-diabetic control activity level. Co-administration of R+G and R+B in diabetic rats significantly decreased CYP3A-associated ERND activities compared to the non-diabetic control group. CYP3A is responsible for the metabolism of both endogenous and exogenous molecules such as drugs. Similarly, GST activities of D+R+G and D+R+B groups were less than the non-diabetic control group. Glutathione S-transferases are also responsible for the elimination of many exogenous molecules and they generally catalyze detoxification reactions. Co-administration of these chemicals may inhibit the metabolism of endogenous and exogenous molecules and may cause a toxic reaction by inhibiting the metabolism of drugs metabolized by CYP3A and GST.