The deleterious effects of cadmium on oxidative stress markers, drug-metabolizing, and antioxidant enzyme activities: Role of Silymarin and Garlic as Antioxidants.

Exposure to cadmium has been related to liver and kidney diseases such as polycystic and nephrotic syndrome. It is still unclear how cadmium contributes to these diseases. It is believed that the induction of oxidative stress resulting from the inhibition of antioxidant enzyme activities and changes in drug-metabolizing enzymes in the liver could explain the role of cadmium in the development of different diseases in the kidney and probably other organs. Changes in oxidative stress markers, antioxidant enzymes, and drug-metabolizing enzyme activities were assessed in the liver of male rats exposed to cadmium chloride. Additionally, the protective effects of silymarin and garlic extract against cadmium toxicosis were evaluated. Rats were randomly divided into eight groups as follows, groups 1, 2, 3, 4, and 5, received orally saline, CdCl2 (1 mg/kg), garlic extract [800 mg/kg], silymarin (25 mg/kg) and silymarin plus garlic extract respectively for 28 consecutive days. Rats in groups 6, 7, and 8 were pretreated with the same doses of garlic, silymarin, and garlic plus silymarin, respectively for two hours before cadmium administration. The Western immunoblotting technique was used to investigate the protein expression of cytochrome P450 isozymes. Spectrophotometric methods were used to assess the activity of both antioxidant- and drug-metabolizing enzymes. Free radical levels [measured as thiobarbituric acid reactive substances (TBARS)], catalase, superoxide dismutase, and glutathione peroxidase activities increased whereas the levels of glutathione and the activities of glutathione S-transferase, glutathione reductase, and glutamyl transferase, cytochrome P450, aryl hydrocarbon dehydrogenase (AHH), dimethylnitrosamine-N-demethylase I (DMN-dI), 7-ethoxycoumarine-O-deethylase (ECOD), cytochrome b5 and NADPH-Cytochrome-c-reductase enzyme activities decreased after cadmium treatment. Furthermore, Western immunoblotting data revealed that glutathione peroxidase protein expression increased following cadmium exposure, but cytochrome P450 2E1 and 3A4 expressions were downregulated. However, pretreatment of rats with silymarin or garlic extract or both before cadmium administration was found to restore the protein expression of cytochrome P450 2E1 and 3A4, the level of free radicals, antioxidant enzymes, drug-metabolizing enzyme activities to their normal levels. Similarly, histological studies revealed that silymarin and/or garlic extract reduced the liver damage caused by cadmium. Silymarin and/or garlic extract reduced the adverse effects of cadmium on the activity of both drug-metabolizing and antioxidant enzymes activity. These antioxidants could be provided to those who work in cadmium-based sectors to help them cope with the adverse effects of cadmium on their kidneys. In addition, Inhibiting drug-metabolizing enzyme activity should be considered when administering therapeutic medications to persons exposed to cadmium because most therapeutic drugs and many endogenous substances are largely metabolized by these enzymes.

Antioxidants (selenium and garlic) alleviated the adverse effects of tramadol on the reproductive system and oxidative stress markers in male rabbits.

Tramadol has been used by millions of patients as an analgesic drug to relief the severe pain caused by cancers and other diseases. The current study aimed to investigate the protective effects of antioxidants (garlic and selenium) against the toxic effects of tramadol on semen characteristics, steroid hormones, the protein expressions of different cytochrome P450 isozymes [CYP 21A2, CYP 19, and 11A1], and on antioxidant enzyme activities in testes of rabbits. Western immunoblotting, spectrophotometric, and histological methods were used in this study. Tramadol (1.5 mg/kg body weight) was administered orally to male rabbits for up to three months (three times/week), and after pretreatment of rabbits with garlic (800 mg/kg) and/or selenium (1 mg/kg body weight) by 2 h. The present study showed that motilities, semen volumes, morphologies, sperm counts, testosterone, and estrogen levels were significantly decreased after 4, 8, and 12 weeks of tramadol treatment. In addition, the protein expressions of CYP 21A2, CYP 19, and 11A1 were down-regulated in the testes of the tramadol-treated rabbits. On the other hand, pretreatment of rabbits with garlic, selenium, and/or garlic-selenium for 2 h before administration of tramadol restored the downregulated CYP 21A2 and 11A1 to their normal levels after 12 weeks of tramadol treatment. Activities of antioxidant enzymes including glutathione reductase, glutathione peroxidase, glutathione S-transferase, catalase, superoxide dismutase, and levels of glutathione were inhibited in the testes of tramadol-treated rabbits. On the other hand, free radical levels were significantly increased in the testes of tramadol-treated rabbits for 12 weeks. Interestingly, such changes in the activities of antioxidant enzymes as well as free radical levels caused by tramadol were restored to their normal levels in the rabbits pretreated with either selenium, garlic, and/or their combination. Histopathological investigations showed that tramadol caused substantial vacuolization with the presence of damaged immature spermatozoid in the testes. However, selenium and garlic treatments showed an increase in healthy sperm production with normal mitotic and meiotic divisions. The present study illustrated for the first time the mechanisms of low steroid hormone levels in the testes of tramadol-treated rabbits which could be due to the downregulation of CYPs proteins, induction of oxidative stress, and inhibition of antioxidant enzyme activities. In addition, the present data showed that such toxic effects of tramadol were attenuated and restored to their normal levels after pretreatment of rabbits with garlic, selenium, and/or their combination. This finding may pave the way for a new approach to reducing the toxicity of tramadol.

Trigonella stellata reduced the deleterious effects of diabetes mellitus through alleviation of oxidative stress, antioxidant- and drug-metabolizing enzymes activities.

ETHNOPHARMACOLOGICAL RELEVANCE: Genus Trigonella has a history of folkloric medicinal uses in China, Japan, Egypt and India. There are a variety of therapeutic actions of Trigonella including hypocholesterolemia, hypoglycemia, antibacterial, antiviral, anti-inflammatory activities, antioxidants and appetite stimulant. AIM OF THE STUDY: The prevalence of diabetes mellitus is increasing annually. The present study aims at investigating the protective effects of Trigonella stellata against the adverse effects of diabetes mellitus through investigation of the changes in phase I & II drug-metabolizing enzyme activities, protein expression of cytochrome P450 isoenzymes [CYP2E1 & 3A4], oxidative stress, antioxidant enzymes as well as histopathology of both liver and kidney tissues. METHODS: GC-MS and MALDI-TOF were used to analyze the main constituents of the aqueous and the ethanolic extract of Trigonella stellata. Western immunoblotting technique used to show the protein expression of CYP450 isozymes in different groups. Spectrophotometric- and fluorophotometric techniques were also used for assessment of different hepatic integrity enzymes. Histopathological techniques used to illustrate the changes in the tissues of both livers and kidneys after different treatments. RESULTS: Trigonelline was found to be the main constituent of both aqueous and ethanolic extract of Trigonella stellata. Administration of the aqueous and/or the ethanolic extracts of Trigonella stellata to the diabetic rats was found to decrease the blood glucose level, the biochemical markers of both liver (transaminases activities, Lactate dehydrogenase, gamma-glutamyl transferase) and the renal functions (urea, creatinine and bilirubin) which were increased in diabetic-treated rats relative to their normal levels. Diabetes mellitus potentially induced the oxidative stress, and also activities of dimethylnitrosamine N-demethylase I, cytochrome c-reductase, ethoxyresourfin O-deethylase, and the total hepatic content of cytochrome P450. On the other hand, the activity of catalase [CAT], superoxide dismutase [SOD], glutathione S-transferase [GST], glutathione reductase [GR], glutathione peroxidase [GPx] and levels of reduced glutathione [GSH] were potentially inhibited in diabetic rats compared to the control rats. However, treatments of diabetic rats with either aqueous and/or ethanolic extracts of Trigonella stellata restored such changes caused by diabetes almost nearly to their normal levels compared to the control group. Supporting the activity of dimethyl nitrosamine N-demethylase I activity, the protein expression of CYP2E1 was also induced in diabetic rats. However, the aqueous extract of Trigonella stellata was more effective than ethanolic extract in restoring the changes in the protein expression of CYP2E. On the other hand, the protein expression of CYP3A4 was markedly decreased in diabetic rats, and this decrease was partially restored to its normal level after treatment of diabetic rats with aqueous and/or ethanolic extracts. In addition, Trigonella stellata extracts alleviated the histopathological changes in livers and kidneys caused by diabetes mellitus. CONCLUSION: It is concluded that diabetes mellitus induced changes in oxidative stress, phase I & II drug-metabolizing enzymes, and antioxidant enzymes activities, whereas both extracts of Trigonella stellata alleviated such changes. Alterations in cytochrome P450 system should be considered when therapeutic drugs are administered to diabetic patients since most of xenobiotic are mainly metabolized by this system.

Protective Effects of Essential Oils as Natural Antioxidants against Hepatotoxicity Induced by Cyclophosphamide in Mice.

Clinical application of cyclophosphamide (CP) as an anticancer drug is often limited due to its toxicity. CP is metabolized mainly in the liver by cytochrome P450 system into acrolein which is the proximate toxic metabolite. Many different natural antioxidants were found to alleviate the toxic effects of various toxic agents via different mechanisms. Therefore, the present study aimed at investigating the role of essential oils extracted from fennel, cumin and clove as natural antioxidants in the alleviation of hepatotoxicity induced by CP through assessment of hepatotoxicity biomarkers (AST, ALT, ALP), histopathology of liver tissues as well as other biochemical parameters involved in the metabolism of CP. The data of the present study showed that treatment of male mice with cyclophosphamide (2.5 mg/Kg BW) as repeated dose for 28 consecutive days was found to induce hepatotoxicity through the elevation in the activities of AST, ALT, and ALP. Combined administration of any of these oils with CP to mice partially normalized the altered hepatic biochemical markers caused by CP, whereas administration of fennel, clove or cumin essential oils alone couldn't change liver function indices. Moreover, CP caused histological changes in livers of mice including swelling and dilation in sinusoidal space, inflammation in portal tract and hepatocytes, as well as, hyperplasia in Kuppfer cells. However, co-administration of any of the essential oils with CP alleviated to some extent the changes caused by CP but not as the normal liver. CP was also found to induce free radical levels (measured as thiobarbituric acid reactive substances) and inhibited the activities of superoxide dismutase, glutathione reductase, and catalase as well as activities and protein expressions of both glutathione S-transferase (GSTπ) and glutathione peroxidase. Essential oils restored changes in activities of antioxidant enzymes (SOD, CAT, GR, GST, and GPx) caused by CP to their normal levels compared to control group. In addition, treatment of mice with CP was found to induce the protein expression of CYP 3A4, 2B1/2, 2C6, 2C23. Moreover, the present study showed that essential oils reduced the expression of CYPs 2E1, 3A4 but could not restore the expression of CYP 2C6 and 2C23 compared to CP-treated mice. Interestingly, pretreatment of mice with essential oil of clove was found to restore activities of DMN-dI, AHH, and ECOD which were induced by CP to their normal control levels. It is concluded that EOs showed a marked hepatoprotective effect against hepatotoxicity induced by CP. In addition, co-administration of CP with any of these oils might be used as a new strategy for cancer treatment to alleviate the hepatotoxicity induced by CP.

Effects of benzo[a]pyrene as an environmental pollutant and two natural antioxidants on biomarkers of reproductive dysfunction in male rats.

Benzo[a]pyrene (B[a]P) is an environmental toxicant and endocrine disruptor. Therefore, the aim of the present study was to investigate the toxicity of B[a]P in testis of rats and also to study the role of silymarin and thymoquinone (TQ) as natural antioxidants in the alleviation of such toxicity. Data of the present study showed that levels of testosterone, estrogen and progesterone were significantly decreased after treatment of rats with B[a]P. In addition, B[a]P caused downregulation of the expressions of steroidogenic enzymes including CYP17A1 and CP19A1, and decreased the activity of 17-ß hydroxysteroid dehydrogenase (17ß-HSD). Moreover, B[a]P decreased the activities of antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD), and significantly increased free radicals levels in testis of male rats. However, pretreatment of rats with silymarin prior to administration of B[a]P was found to restore the level of free radicals, antioxidant status, and activities of steroidogenic enzymes to their normal levels in testicular tissues. Moreover, histopathological finding showed that silymarin recovered the abnormalities occurred in tubules caused by B[a] P in testis of rats. On the other hand, TQ showed pro-oxidant effects and did not ameliorate the toxic effects of B[a] P on the testicular tissue since it decreased antioxidant enzymes activities and inhibited the protein expression of CYP11A1 and CYP21A2 compared to control rats. Moreover, TQ decreased the levels of testosterone, estrogen, and progesterone either in the presence or absence of B[a]P. It is concluded that B[a]P decreased testosterone levels, inhibited antioxidant enzymes activities, caused downregulation of CYP isozymes involved in steroidogenesis, and increased free radical levels in testis. Moreover, silymarin was more effective than TQ in restoring organism health and alleviating the deleterious effects caused by B[a]P in the testis of rats. Due to its negative impact, it is highly recommended to limit the use of TQ as a dietary supplement since millions of people in the Middle East are using it to improve their health.