Enhanced Glutathione S-transferase Activity Research Articles

Clotrimazole is effective, safe and tolerable for the treatment of endometriosis and functions by downregulating inducible nitric oxide synthase and modulating oxidative stress biomarkers

This study investigated the mechanism of action of clotrimazole (CTZ) and its adverse effects in a model of endometriosis. After autologous endometrial implantation, 18 rats were randomized into two treatment groups: 200 mg/kg CTZ or vehicle for 15 consecutive days. The lesion growth, implant size, glandular atrophy, nitric oxide (NO) serum levels, number of macrophage cells and inducible nitric oxide synthase (iNOS) immunoreactivity were significantly reduced in the CTZ group compared with the control. CTZ (p < 0.05) reduced the lipid peroxidation and protein carbonylation levels in the liver but did not alter the superoxide dismutase (SOD), glutathione (GSH) or glutathione S-transferase (GST) levels in the brain; however, the drug significantly reduced SOD activity and enhanced GST activity in the liver. These results suggest that CTZ interferes with reactive nitrogen species production by downregulating iNOS expression and thus enhances the antioxidant system to promote atrophy and regression of endometriotic lesions, without adverse effects on the brain and/or liver.

MOSQUITO LARVICIDAL POTENCY OF SELECTED HALOPHYTE SPECIES AND THEIR MODULATION ON ACETYLCHOLINESTERASE AND GLUTATHIONE S-TRANSFERASE AGAINST DENGUE VECTOR: Aedes aegypti

A mangrove is an ecosystem that represents a natural product reservoir of biotechnological interest. They have been advocated as environmentally benign alternatives to synthetic pesticides against all vector mosquitos. The purpose of this study was to determine the larvicidal activities of selected mangrove plant extracts against Aedes aegypti mosquito larvae. Methanol extracts of three selected halophytes viz. Lumnitzera racemosa, Bruguiera cylindrica, and Excoecaria agallocha were made, phytochemically investigated and evaluated against A. aegypti early 4th instar larvae. Acetylcholinesterase (AChE) activity and Glutathione S-transferase (GST) activity were evaluated, followed by DNA extraction and fragmentation tests. GC-MS technique was used to determine the presence of bioactive chemicals. Alkaloids, flavonoids, terpenoids, anthocyanin, coumarins, phenolic compounds, and quinones were found in all plants. The best larvicidal activity was recorded in the L. racemosa flower buds (LC50- 0.766 mg/ml) and E. agallocha stem extract (LC50- 0.986 mg/ml). L. racemosa flower buds and E. agallocha stem exhibited higher inhibition in Acetylcholinesterase (AChE) activity with the rate of 1.39 μmol ACT/min/mg protein and 1.65 μmol ACT/min/mg protein (p &lt; 0.05) in treated larvae. In the case of L. racemosa flower buds, however, enhanced GST activity was detected. Plant extracts were found not to cause any fragmentation activity in the larval DNA. 5 major peaks of chemical compounds were analyzed in L. racemosa and E. agallocha. Because of the possible larvicidal action of selected halophyte extracts, they can be utilized as ecologically friendly mosquitocide for eradicating dengue vector larvae in their early stages.

Effect of Acrylamide Treatment on Cyp2e1 Expression and Redox Status in Rat Hepatocytes.

Acrylamide (AA) toxicity is associated with oxidative stress. During detoxification, AA is either coupled to gluthatione or biotransformed to glycidamide by the enzyme cytochrome P450 2E1 (CYP2E1). The aim of our study was to examine the hepatotoxicity of AA in vivo and in vitro. Thirty male Wistar rats were treated with 25 or 50 mg/kg b.w. of AA for 3 weeks. Qualitative and quantitative immunohistochemical evaluation of inducible nitric oxide synthase (iNOS), CYP2E1, catalase (CAT), superoxide dismutase 1 (SOD1), and SOD2 expression in liver was carried out. Bearing in mind that the liver is consisted mainly of hepatocytes, in a parallel study, we used the rat hepatoma cell line H4IIE to investigate the effects of AA at IC20 and IC50 concentrations on the redox status and the activity of CAT, SOD, and glutathione-S-transferase (GST), their gene expression, and CYP2E1 and iNOS expression. Immunohistochemically stained liver sections showed that treatment with AA25mg induced a significant decrease of CYP2E1 protein expression (p < 0.05), while treatment with AA50mg led to a significant increase of iNOS protein expression (p < 0.05). AA treatment dose-dependently elevated SOD2 protein expression (p < 0.05), while SOD1 protein expression was significantly increased only at AA50mg (p < 0.05). CAT protein expression was not significantly affected by AA treatments (p > 0.05). In AA-treated H4IIE cells, a concentration-dependent significant increase in lipid peroxidation and nitrite levels was observed (p < 0.05), while GSH content and SOD activity significantly decreased in a concentration-dependent manner (p < 0.05). AA IC50 significantly enhanced GST activity (p < 0.05). The level of mRNA significantly increased in a concentration-dependent manner for iNOS, SOD2, and CAT in AA-treated H4IIE cells (p < 0.05). AA IC50 significantly increased the transcription of SOD1, GSTA2, and GSTP1 genes (p < 0.05), while AA IC20 significantly decreased mRNA for CYP2E1 in H4IIE cells (p < 0.05). Obtained results indicate that AA treatments, both in vivo and in vitro, change hepatocytes; drug-metabolizing potential and disturb its redox status.

Multiple effects of silicon on alleviation of arsenic and cadmium toxicity in hyperaccumulator Isatis cappadocica Desv.

Arsenic (As) and cadmium (Cd) belong to the group of major pollutants extremely toxic to plants. Metal hyperaccumulating plants play an important role in phytoextraction of heavy metals. Silicon (Si) plays an important role in the amelioration of heavy metal stress through physio-biochemical mechanisms, which remain poorly understood in hyperaccumulators. The main purpose of this study was to determine the impact of Si on growth and performance of As hyperaccumulator Isatis cappadocica Desv., exposed to As and Cd. Results showed that Si (especially at 1 mM level) alleviated the harmful impact of As/Cd and significantly increased the root and shoot biomass, root and shoot length and chlorophyll contents of I. cappadocica by enhancing the plant defense mechanisms. Between the two investigated harmful elements, As was accumulated in plant parts significantly more than Cd, however with considerably lower toxic growth effects. The As/Cd concentration, bioaccumulation and translocation factor and total As content both in roots and shoots of Si-supplied plant were significantly reduced as a protective mechanism, especially in Cd exposed plant. In comparison with single As/Cd treatment, Si supply reduced H2O2 content, increased total soluble protein content and enhanced glutathione S-transferase activity in shoots. The results of this study clearly showed that Si minimized As/Cd uptake and root to shoot translocation, and therefore Si cannot enhance the phytoextraction potential of this plant species. Additionally, Si-improved growth and reduced oxidative damages caused by excess of As and Cd suggested that the similar mechanisms of metal(loid) alleviation are adopted in hyperaccumulators as well as non-hyperaccumulating plants.

Ammonia exposure and subsequent recovery trigger oxidative stress responses in juveniles of Brazilian flounder Paralichthys orbignyanus.

The effects of ammonia exposure and recovery on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus were evaluated. The fish were exposed to 0.12, 0.28 and 0.57mgNH3-NL-1, plus a control, for 10days followed by the same recovery time in ammonia-free water. Gill, liver and muscle samples (n=9) were collected after 1, 5 and 10days of exposure and after recovery for oxidative stress analysis (antioxidant capacity against peroxyl radicals (ACAP); glutathione S-transferase (GST) activity; lipoperoxidation levels measured through thiobarbituric acid reactive substances (TBARS) content). For histological assessment, gill, liver and brain samples were collected. Exposure to all NH3-N concentrations induced different time- and dose-dependent changes in oxidative stress parameters. Reduced antioxidant capacity of the liver and muscle and enhanced TBARS levels in the gills and liver were demonstrated. Differently, a high ammonia concentration elicited lower hepatic TBARS levels. Enhanced GST activity in all organs and increased antioxidant capacity of the gills were also observed. No ammonia-induced histopathological effects were demonstrated. After recovery, most parameters (liver ACAP, GST activity in the muscle and liver and TBARS in the gills) returned to baseline levels. However, liver TBARS and gill GST activity remained altered 0.57mgNH3-NL-1 treatment. The recovery period also led to a decrease in gill antioxidant capacity and an increase in muscle antioxidant capacity. In conclusion, a concentration of 0.12mgNH3-NL-1 induces oxidative stress and antioxidant responses in juvenile Brazilian flounder. Moreover, a 10-day recovery period is not sufficient to restore fish homeostasis.

Environmental Tobacco Smoke Induces Oxidative Stress in Distinct Brain Regions of Infant Mice

Environmental tobacco smoke (ETS) leads to the death of 600,000 nonsmokers annually and is associated with disturbances in antioxidant enzyme capacity in the adult rodent brain. However, little is known regarding the influence of ETS on brain development. The aim of this study was to determine levels of malonaldehyde (MDA) and 3-nitrotyrosine (3-NT), as well as enzymatic antioxidant activities of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione S-transferase (GST), and superoxide dismutase (SOD), in distinct brain structures. BALB/c mice were exposed to ETS twice daily for 1 h from postnatal day 5 through postnatal day 18. Acute exposure was performed for 1 h on postnatal day 18. Mice were euthanized either immediately (0) or 3 h after the last exposure. Immediately after an acute exposure there were higher GR and GST activities and MDA levels in the hippocampus, higher GPx and SOD activities in the prefrontal cortex, and higher GST activity and MDA levels in the striatum and cerebellum. Three hours later there was an increase in SOD activity and MDA levels in the hippocampus and a decrease in the activity of all enzymes in the prefrontal cortex. Immediately after final repeated exposure there were elevated levels of GST and GR activity and decreased GPx activity in the hippocampus. Moreover, a rise was found in GPx and GST activities in the prefrontal cortex and increased GST and GPx activity in the striatum and cerebellum, respectively. After 3 h the prefrontal cortex showed elevated GR and GST activities, and the striatum displayed enhanced GST activity. Data showed that enzymatic antioxidant system in the central nervous system responds to ETS differently in different regions of the brain and that a form of adaptation occurs after several days of exposure.

Sublethal Effects of Three Pesticides on Activities of Selected Target and Detoxification Enzymes in the Aquatic Midge, Chironomus tentans (Diptera: Chironomidae)

Sublethal effects of three pesticides including atrazine (triazine herbicide), DDT (organochlorinated insecticide), and chlorpyrifos (organophosphate insecticide) on acetylcholinesterase (AChE), general esterase (GE), glutathione S-transferase (GST), and cytochrome P450 monooxygenase (P450) activities were evaluated in the aquatic midge Chironomus tentans. Exposures of midges to atrazine at 30 and 150 micrograms per liter (microg/L) for 20 d (i.e., from the first- to fourth-instar larvae) enhanced P450 O-deethylation activity by 12.5- and 15.5-fold, respectively, but did not significantly change AChE, GST, and GE activities. Similar exposures to DDT at 0.01 and 0.05 microg/L did not significantly affect AChE, GE, and P450 activities; however, DDT at 0.05 microg/L enhanced GST activity toward the substrate 1-chloro-2, 4-dinitrobenzene by 33.6%. Exposures of midges to chlorpyrifos at 0.10 microg/L for 20 d reduced AChE activity by 59.8%, and GE activities toward the substrates alpha-naphthyl acetate and beta-naphthyl acetate by 30.7 and 48.8%, respectively. The reduced GE activities appear to be due to the inhibition of several esterases, particularly the one with a slow migration, by chlorpyrifos as demonstrated by non-denaturing polyacrylamide gel electrophoresis. Furthermore, exposure of midges to chlorpyrifos at 0.10 microg/L for 20 d enhanced the P450 O-deethylation activity by 3.3-fold although no significant effect was observed at 0.02 microg/L for the same enzyme. These results provide insights into the sublethal effects of these commonly detected pesticides in aquatic environments on important enzymes in aquatic midges.

PLASMA GLUTATHIONE S-TRANSFERASE π1-1 AND α1-1 LEVELS IN PATIENTS WITH BLADDER CANCER

No AccessJournal of UrologyINVESTIGATIVE UROLOGY1 Dec 2000PLASMA GLUTATHIONE S-TRANSFERASE π1-1 AND α1-1 LEVELS IN PATIENTS WITH BLADDER CANCER CHRIS L. BERENDSEN, THEO P.J. MULDER, and WILBERT H.M. PETERS CHRIS L. BERENDSENCHRIS L. BERENDSEN More articles by this author , THEO P.J. MULDERTHEO P.J. MULDER More articles by this author , and WILBERT H.M. PETERSWILBERT H.M. PETERS More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(05)66982-0AboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract Purpose: Transitional cell carcinomas of the human bladder and many gastrointestinal tumors often contain high amounts of the detoxification enzyme glutathione S-transferase π (GSTP1-1). Elevated levels of GSTP1-1 have been found in serum and plasma from patients with gastrointestinal, lung or head and neck cancer. GSTP1-1 and glutathione S-transferase α (GSTA1-1) have been reported to be increased in 10 of 15 patients (67%) with bladder cancer. We evaluate the role of GSTP1-1 and GSTA1-1 as plasma tumor markers in 50 patients with bladder cancer before and after treatment. Materials and Methods: Blood from patients with bladder cancer was sampled in ethylenediaminetetraacetic acid tubes. Plasma GSTA1-1 and GSTP1-1 were measured using the sensitive and specific sandwich enzyme-linked immunosorbent assay. Results: Respective plasma GSTA1-1 and GSTP1-1 levels were above the upper normal reference limit in 2 (4%) and 14 (28%) of the 50 patients with bladder cancer. No significant decrease in plasma GSTA1-1 or GSTP1-1 was noted in matched pairs of plasma samples collected before and after treatment. Conclusions: In contrast to earlier reports, only a limited number of patients with bladder cancer had increased plasma GSTA1-1 or GSTP1-1, which did not decrease after tumor resection. These findings argue against the use of GSTP1-1 or GSTA1-1 as plasma markers for bladder cancer. References 1 : The glutathione S-transferase supergene family: regulation of GST and the contribution of the isoenzymes to cancer chemoprotection and drug resistance. Crit Rev Biochem Mol Biol1995; 30: 445. Google Scholar 2 : Nomenclature for human glutathione transferases. Biochem J1992; 282: 305. Google Scholar 3 : Preparation, characterization and properties of glutathione S-transferases. In: . Edited by . New York: Wiley J and Sons1985: 297. Google Scholar 4 : The isoenzymes of glutathione S-transferase. In: Advances in Enzymology. Edited by . New York: Wiley J and Sons1985: 357. Google Scholar 5 : Glutathione S-transferases: biomedical applications. Adv Clin Chem1993; 30: 282. Google Scholar 6 : Glutathione transferases and cancer. Crit Rev Biochem Mol Biol1992; 27: 337. Google Scholar 7 : Glutathione S-transferase activity and subunit composition in transitional cell cancer and mucosa of the human bladder. Urology1997; 49: 644. Google Scholar 8 : Enhanced glutathione S-transferase activity and glutathione content in human bladder cancer. Follow up study: influence of smoking. J Urol1993; 149: 1452. Google Scholar 9 : Glutathione S-transferase activity in human superficial transitional cell carcinoma of the bladder. Cancer1990; 9: 2064. Google Scholar 10 : Enzyme immunoassay for human serum glutathione S-transferase pi using monoclonal and polyclonal antibodies. Cancer J1989; 2: 225. Google Scholar 11 : Serum glutathione S-transferase-pi as a tumor marker for gastrointestinal malignancies. Cancer1989; 63: 317. Google Scholar 12 : Elevation of the placental glutathione S-transferase form (GST-pi) in tumor tissues and the level in sera of patients with cancer. Cancer Res1989; 49: 5225. Google Scholar 13 : Serum glutathione S-transferase-pi level as a tumor marker for non-small cell lung cancer. Cancer1994; 73: 1377. Google Scholar 14 : Radioimmunoassay for plasma glutathione S-transferase-pi and its clinical application in gastrointestinal cancer. Cancer1995; 76: 1363. Google Scholar 15 : Significance of glutathione S-transferase-pi as a tumor marker in patients with oral cancer. Cancer1992; 70: 2381. Google Scholar 16 : Isoenzyme-specific quantitative immunoassays for cytosolic glutathione transferases and measurement of the enzymes in blood plasma from cancer patients and in tumor cell lines. Biochim Biophys Acta1994; 1225: 223. Google Scholar 17 : Sandwich ELISA for glutathione S-transferase Alpha 1-1: plasma concentrations in controls and in patients with gastrointestinal disorders. Clin Chem1996; 42: 416. Google Scholar 18 : Measurement of glutathione S-transferase P1–1 in plasma; pitfalls and significance for screening and follow-up of patients with gastrointestinal cancer. Cancer1997; 80: 873. Google Scholar 19 : Hepatocellular integrity in liver donors and recipients indicated by glutathione transferase alpha. Transplantation1996; 61: 904. Google Scholar 20 : Glutathione S-transferase alpha as a marker for hepatocellular damage in pre-eclampsia and HELLP syndrome. Lancet1995; 345: 1571. Google Scholar From the Department of Urology, Atrium Medical Center Heerlen, Heerlen and Department of Gastroenterology, University Hospital St. Radboud, Nijmegen, The Netherlands© 2000 by American Urological Association, Inc.FiguresReferencesRelatedDetails Volume 164Issue 6December 2000Page: 2126-2128 Advertisement Copyright & Permissions© 2000 by American Urological Association, Inc.Keywordsglutathione transferasetumor markers, biologicalenzyme-linked immunosorbent assaybladder neoplasmsMetricsAuthor Information CHRIS L. BERENDSEN More articles by this author THEO P.J. MULDER More articles by this author WILBERT H.M. PETERS More articles by this author Expand All Advertisement PDF downloadLoading ...

Contribution of Caffeine and Flavanols in the Induction of Hepatic Phase II Activities by Green Tea

Aqueous extracts of green tea, at concentrations of 2.5, 5.0 and 7.5%, were administered to rats as the sole drinking fluid for 4 weeks. Hepatic glutathione S-transferase (GST) activity, determined using 1-chloro-2,4-dinitrobenzene (CDNB) and 3,4-dichloronitrobenzene (DCNB) as substrates, and UDP-glucuronosyl transferase activity, determined using 2-aminophenol as substrate, were induced but the effect was not always dose dependent. At the two highest doses, hepatic catalase activity was inhibited. In a second study, animals were exposed for 4 weeks to aqueous extracts (2.5%, v/v) of green tea, black tea (which has a much lower content of flavanols compared with green tea) and decaffeinated black tea. Treatment with the black tea enhanced GST activity, whether monitored using CDNB or DCNB, and the glucuronidation of 2-aminophenol. Treatment with decaffeinated black tea failed to modulate any of these activities, whereas treatment with green tea only enhanced the glucuronidation of 2-aminophenol. Finally, at this concentration of tea extract administration, black and decaffeinated black tea, but not green tea, suppressed catalase activity. It is concluded that neither flavanols nor caffeine are responsible for the induction of hepatic Phase II activities and inhibition of catalase activity in the rat.

Effects of Neem Flowers, Thai and Chinese Bitter Gourd Fruits and Sweet Basil Leaves on Hepatic Monooxygenases and Glutathione S-transferase Activities, and In Vitro Metabolic Activation of Chemical Carcinogens in Rats

The objectives of this study were to determine the effects of feeding of four vegetables commonly consumed in Thailand, namely, flowers of the neem tree ( Azadirachta indica var. siamensis), fruits of Thai and the Chinese bitter gourd ( Momordica charantia Linn.) and leaves of sweet basil ( Ocimum basilicum Linn) on the levels of phase I enzymes, which include cytochrome P450 ( P450), aniline hydroxylase (ANH) and aminopyrine- N-demethylase (AMD) as well as the capacity to activate the mutagenicities of aflatoxin B 1 (AFB 1) and benzo[ a]pyrene (BaP), and to induce the phase II enzymes [i.e. glutathione S-transferase (GST)] in rat liver. It was found that feeding of the diets containing 12.5% neem flowers and Thai bitter gourd fruits for 2 weeks strongly enhanced GST activity, 2.7- and 1.6- fold of the pair-fed control values, respectively, while resulting in a marked reduction of the levels of most phase I reactions. Fruits of the Chinese bitter gourd, which is in the same species as Thai bitter gourd, had no effect on GST activity but decreased AMD activity and the in vitro metabolic activation of AFB 1 and BaP. On the other hand, however, dietary sweet basil leaves caused a significant increase in the levels of both GST and all phase I enzymes. Results in the present study clearly demonstrate that neem flowers and Thai bitter gourd fruits contain monofunctional phase II enzyme inducers and compounds capable of repressing some monooxygenases, especially those involved in the metabolic activation of chemical carcinogens, while sweet basil leaves contain compounds, probably bifunctional inducers, capable of inducing both phase I and phase II enzymes and Chinese bitter gourd fruits contain only compounds capable of repressing some monooxygenases. These results therefore suggest that neem flowers and Thai bitter gourd fruits may possess chemopreventive potential, while those of Chinese bitter gourd fruits and sweet basil leaves are uncertain.

Effects of the sulforaphane analog compound 30, indole-3-carbinol, d-limonene or relafen on glutathione S-transferases and glutathione peroxidase of the rat digestive tract

Several dietary compounds have been demonstrated to reduce gastrointestinal cancer rates in both humans and animals. We showed that high human gastrointestinal tissue levels of glutathione S-transferase (GST), a family of detoxification enzymes consisting of class Alpha, Mu, Pi and Theta isoforms, were inversely correlated with cancer risk. We now investigated whether the sulforaphane analog compound 30, indole-3-carbinol, d-limonene or relafen, supplemented in the diet for two weeks at 1450, 250, 10 000, and 200 ppm, respectively, influenced (i) GST activity, (ii) GST isoenzyme levels, (iii) GSH levels, or (iv) glutathione peroxidase (GPx) activity in the gastrointestinal tract of male Wistar rats. Sulforaphane analog compound 30 enhanced GST activity in all organs studied (1.2–2.4×). It induced GST Alpha levels in small intestine and liver, GST Mu levels in stomach and small intestine, GST Pi levels in stomach and small and large intestine, and GSH levels in stomach and proximal and middle small intestine. Indole-3-carbinol induced gastric GST Mu and hepatic GST Alpha levels. d-limonene induced hepatic GST Alpha, colonic GST Pi levels and proximal small intestinal GST enzyme activity and GST Pi levels. Relafen induced hepatic GST Alpha levels, distal small intestinal and gastric GST Pi levels, and oesophageal and proximal small intestinal GSH levels. GPx activity was enhanced by relafen in oesophagus, and in distal small intestine by sulforaphane analog compound 30. Enhancement of GSTs and to a lesser extent GPx and GSH, resulting in a more efficient detoxification, may explain at least in part the anticarcinogenic properties of sulforaphane analog compound 30, and to a much lesser extent of indole-3-carbinol and d-limonene.

Benomyl

The objectives of this study were to determine the effects of feeding of four vegetables commonly consumed in Thailand, namely, flowers of the neem tree (Azadirachta indica var. siamensis), fruits of Thai and the Chinese bitter gourd (Momordica charantia Linn.) and leaves of sweet basil (Ocimum basilicum Linn) on the levels of phase I enzymes, which include cytochrome P450 (P450), aniline hydroxylase (ANH) and aminopyrine-N-demethylase (AMD) as well as the capacity to activate the mutagenicities of aflatoxin B1 (AFB1) and benzo[a]pyrene (BaP), and to induce the phase II enzymes [i.e. glutathione S-transferase (GST)] in rat liver. It was found that feeding of the diets containing 12.5% neem flowers and Thai bitter gourd fruits for 2 weeks strongly enhanced GST activity, 2.7- and 1.6- fold of the pair-fed control values, respectively, while resulting in a marked reduction of the levels of most phase I reactions. Fruits of the Chinese bitter gourd, which is in the same species as Thai bitter gourd, had no effect on GST activity but decreased AMD activity and the in vitro metabolic activation of AFB1 and BaP. On the other hand, however, dietary sweet basil leaves caused a significant increase in the levels of both GST and all phase I enzymes. Results in the present study clearly demonstrate that neem flowers and Thai bitter gourd fruits contain monofunctional phase II enzyme inducers and compounds capable of repressing some monooxygenases, especially those involved in the metabolic activation of chemical carcinogens, while sweet basil leaves contain compounds, probably bifunctional inducers, capable of inducing both phase I and phase II enzymes and Chinese bitter gourd fruits contain only compounds capable of repressing some monooxygenases. These results therefore suggest that neem flowers and Thai bitter gourd fruits may possess chemopreventive potential, while those of Chinese bitter gourd fruits and sweet basil leaves are uncertain.

Enhanced Glutathione S-transferase Activity and Glutathione Content in Human Bladder Cancer. Followup Study: Influence of Smoking

Glutathione content and glutathione S-transferase activity have been studied in human bladder specimens obtained from controls and from patients with superficial transitional cell carcinoma (tumor samples and peri-tumor normal tissues from the same patient). After combining an earlier study from our laboratory with the additional material presented (9 healthy controls and 25 transitional cell carcinoma patients), it can be observed that glutathione S-transferase activity was significantly greater in tumor than in peri-tumor normal tissue (34 patients, p <1×10−7) or in normal mucosa (17 controls, p <1×10−3). Glutathione content was significantly greater in tumor than in peri-tumor normal tissue (p <5×10−3) or in normal mucosa (p <2×10−2), with this increase being evident only in smokers. When comparing normal mucosa and peri-tumor samples no significant differences were found either for glutathione S-transferase activity or for glutathione content. Results demonstrate the relationship between the glutathione S-transferase/glutathione system and development of transitional cell carcinoma, as well as its role in cellular resistance to chemotherapy.

Suppressive effect of geniposide on the hepatotoxicity and hepatic DNA binding of aflatoxin B1 in rats

The effects of geniposide pretreatment on both hepatic aflatoxin B1 (AFB1)-DNA binding and AFB1 hepatotoxicity in rats has been examined. For these studies, male Sprague-Dawley rats were treated with AFB1 (2 mg/kg) by i.p. administration, and the different degrees of hepatic damage were revealed by the elevations of levels of serum marker enzymes such as aspartate aminotransferase (AST), alanine amino-transferase (ALT) and gamma-glutamyltranspeptidase (gamma-GT). After pretreatment of animals with geniposide (10 mg/kg) daily for 3 consecutive days, the enzyme elevations were significantly suppressed. This suggested that the geniposide possessed chemopreventive effects on the early acute hepatic damage induced by AFB1. Under these experimental conditions, consistent elevation of the activities of glutathione S-transferase (GST) and gamma-glutamylcysteine synthetase but not glutathione peroxidase (GSH-Px) and gamma-glutamyltranspeptidase were observed. Treatment of rats with geniposide significantly lowered hepatic GSH and GSSG levels, but the ratio of GSH to GSSG was not changed. Geniposide treatment also decreased AFB1-DNA adduct formation in AFB1-treated animals. From these results, we suggest that the protective effect of geniposide on AFB1 hepatotoxicity in rats might be due to the hepatic tissues' defense mechanisms that involve the enhanced GST activity for AFB1 detoxication and induction gamma-glutamylcysteine synthetase for GSH biosynthesis.

Age-development and inducibility of hepatic glutathione S-transferase activities in mice, rats, rabbits and guinea-pigs

1. Hepatic glutathione S-transferase (GST) activities towards l-chloro-3,4-dinitrobenzene (DNCB), 3,4-dichloronitrobenzene (DCNB), sulfobromophthalein (BSP), p-nitrobenzyl chloride (NBC), ethacrynic acid (EA), trans-4-phenyl-3-buten-2-one (TPBO) and 1,2-epoxy-3-( p-nitrophenoxy)propane (ENPP) were determined in mice, rats, rabbits and guinea-pigs during ageing and after pretreatment with enzyme inducers. 2. Variations were observed (a) in the developmental patterns and (b) in the phenobarbital-, benzo(a)pyrene-, pregnenolone-16α-carbonitrile-, butylated hydroxyanisole-, trans-stilbene oxide-inducibility of hepatic GST activities in the same species towards different substrates. 3. For example, in rats GST activities for EA, DCNB and TPBO increased respectively, 2.3-, 4.8- and 25-fold during age-development, and after treatment with TSO 1.2-, 3.6- and 1.3-fold. 4. Species differences were found (a) in the maturation and (b) in the inducibility of GST activities. For instance, GST activity toward EA at birth is mature in guinea pigs but not in the other species; phenobarbital treatment increased GST activities in mice and rats but not in rabbits and guinea-pigs; treatment with trans-stilbene oxide enhanced GST activity for TPBO 4.5-fold in mice but not at all in rats. 5. It is concluded that hepatic glutathione conjugation exhibits functional heterogeneity which may be due to species dependent variations in the responsiveness of GST isoenzymes to endogenous and exogenous influences.