Aleksandar Rašković

The Protective Effects of Silymarin against Doxorubicin-Induced Cardiotoxicity and Hepatotoxicity in Rats

Silymarin is a complex of five major compounds, and silibinin is the most biologically active component of the complex. The aim of this study was to investigate, evaluate and confirm the potential cardioprotective and hepatoprotective effects of administration of silymarin, rich in silibinin, at a dose of 60 mg/kg orally for a time-span of 12 days on doxorubicin induced toxicity in male Wistar rats. The in vivo model was used to explore whether silymarin could prevent damage of liver and heart tissue induced by doxorubicin administered every other day at dose of 1.66 mg/kg intraperitoneally for twelve days. In the study the change of body weight, ECG changes, biochemical parameters of oxidative stress, serum activity of alanine and aspartate transaminase, lactate dehydrogenase, creatine kinase and histological preparations of heart and liver samples of treated animals were examined. According to physiological, pharmacological, microscopic and biochemical results, we confirmed that at the examined dose, silymarin exhibits a protective influence on the heart and liver tissue against toxicity induced by doxorubicin.

The influence of 3α,7α-dihydroxy-12-keto-5β-cholanate on gliclazide pharmacokinetics and glucose levels in a rat model of diabetes

SummaryThe aim of this study was to investigate the pharmacokinetics and glucose-lowering activity of gliclazide alone and in combination with the bile acid salt, sodium 3α,7α-dihydroxy-12-keto-5β-cholanate (MKC), in a rat model of type I diabetes. Eighty male Wistar rats were divided into eight groups (n=10). Four groups were treated with alloxan (30 mg/kg) to induce diabetes. One group of healthy and one group of diabetic rats were administered gliclazide (20 mg/kg), MKC (4 mg/kg) or a combination of gliclazide (20 mg/kg) and MKC (4 mg/kg). One group of healthy and one group of diabetic rats were used as controls. Blood samples were collected from the tail vein 6 hours post-dose and the plasma was analyzed for glucose concentrations. It was found that gliclazide bioavailability was increased in healthy rats when coadministered with MKC, but there was no difference in glucose levels. Gliclazide bioavailability was much lower in diabetic rats and was not altered by MKC. However, the hypoglycemic effect of the combination of gliclazide and MKC was significantly greater in diabetic rats than that of gliclazide alone. It was demonstrated that the combination of MKC and gliclazide produced a significant hypoglycemic effect in a rat model of Type I diabetes. As gliclazide alone does not have a hypoglycemic effect on Type 1 diabetic rats, it can be concluded that gliclazide potentiates hypoglycemic effect of MKC in Type 1 diabetic rats.

Effect of stevioside and sodium salt of monoketocholic acid on glycemia in normoglycemic and diabetic rats

SummaryThis study investigated the effect of a commercial preparation of stevioside and a synthetic compound, sodium salt of monketocholic acid (MKC), administered per os (p.o.) and also adminstered via an osmotic pump, on glycemia in normoglycemic and diabetic Wistar rats. Diabetes was induced with alloxan, 100 mg/kg, i.p. Normoglycemic and diabetic rats were treated p.o. for five days either with physiological solution (1 ml/kg, controls), stevioside (20 mg/kg), MKC (4 mg/kg) and a combination of stevioside (20 mg/kg) and MKC (4 mg/kg). Apart from p.o. adminstration, stevioside and MKC were also administered via a subcutaneously (s.c.) implanted osmotic pump. During treatment and upon termination of the latter, glycemia was measured and the rats that were treated p.o. were subjected to the oral glucose tolerance test (OGTT) at a dose of 1 g/kg. Following this animals were anesthetized with urethane (0.75 g/kg, i.p.) and killed by cardiopunction to determine C-peptide levels in the serum. In all three groups of normoglycemic rats highest decrease in glucose levels was observed on the fourth day of the experiment. The stevioside + MKC combination showed a stronger hypoglycemic effect compared to individual treatments with stevioside and MKC (3.73:4.80:4.73 mmol/L). In the group of diabetic rats that received both substances via the osmotic pump, the hypoglycemic action was also stronger compared to the individual treatments with stevioside and MKC (16.15:18.89:18.75 mmol/L). The treatment of healthy rats with both substances p.o. caused no statistically significant difference in glycemia, whereas in diabetic rats the combination of stevioside + MKC showed a statistically significant decrease in glycemia compared to control values. In both groups of rats, treatment with stevioside and MKC and their combination prevented an increase in glucose concentrations in the OGTT. Only the administration of stevioside by osmotic pump yielded a statistically significant increase in the concentrations of C-peptide in the serum of healthy rats. Compared to controls, the concentrations of C-peptide in diabetic rats were significantly higher after treatment with either stevioside or its combination with MKC, irrespective of the mode of administration.

The effect of celery and parsley juices on pharmacodynamic activity of drugs involving cytochrome P450 in their metabolism

SummaryCelery (Apium graveolens) and parsley (Petroselinum sativum), plants used worldwide in human nutrition, are the natural sources of methoxsalen. In this study we investigated the effect of mice pretreatment with juices of this plants on the hypnotic action of pentobarbital and analgesic action of paracetamol and aminopyrine, the drugs involving cytochrome P450 superfamily in their metabolism. In mice pretreated with celery and parsley juices a prolonged action of pentobarbital with respect to control was observed, statistical significance being attained only with parsley-pretreated animals. Both pretreatments increased and prolonged the analgesic action of aminopyrine and paracetamol, pretreatment with parsley being again more effective. Celery and parsley juices given to animals two hours before their decapitation caused a significant decrease of cytochrome P450 in the liver homogenate as compared to control.

Glucose concentration in the blood of intact and alloxan-treated mice after pretreatment with commercial preparations of Stevia rebaudiana (Bertoni).

SummaryThe study was concerned with the effect of mice pretreatment with two commercial products of Stevia rebaudiana Bertoni on the blood glucose concentration. One group of mice was pretreated four days with 200 mg/kg of Stevita (Stevita Co, INC, Arlington Texas) (stevia) and the other with 20 mg/kg of Clear Steviosides liquid (Stevita Co, INC, Herbal supplement, Brazil) (stevioside), whereas the animals of control group received at the same time physiological solution. Blood glucose concentration was measured before pretreatment and four days after that. The changes in glucose level were provoked by glucose-tolerance test (500 mg/kg, p. o. ) and subcutaneous injection of adrenaline (0. 2 mg/kg). The same procedure of measuring blood glucose was applied on the mice with alloxan-induced diabetes mellitus (two doses of 100 mg/kg with a 24-hour interval).Blood glucose levels in mice pretreated with stevia and stevioside were lower compared with control (7. 82: 6. 82: 8. 01). Also, a smaller increase in this parameter compared to control was registered with pretreated mice in thw glucose-tolerance test, pretreatment with stevioside being again more effective (8. 68: 6. 36: 5. 82). Pretreatment with stevioside being caused no significant increase in blood glucose concentration after administering adrenaline, which was not the case with the animals pretreated with stevia and control. Pretreatment with stevia, and to a greater extent with stevioside, protected test animals from the toxic action of alloxan compared with controls.

Effect of rat pretreatment with aqueous solutions of stevioside and bile acids on the action of certain cardioactive drugs

SummaryThe interaction of aqueous solutions of stevioside and bile acids with cardioactive drugs was studied in rats by registering changes in their electrocardiograms (ECG). Wistar rats of both sexes received daily doses of 20 mg/kg (i.p.) of an aqueous solution of stevioside or physiological solution (controls), then were narcotized with urethane and connected to the ECG apparatus for the first recording. The jugular vein was prepared and connected to an infusion pump to administer one of the drugs: adrenaline (0.1 mg/ml), verapamil (2.5 mg/ml) or metoprolol (1 mg/ml) to rats in both groups, while recording their ECGs. In the second part of the study, the animals were treated in the same way but instead of the stevioside solution received a single dose of 4 mg/kg of monoketocholic acid methyl ester (ME) or sodium salt of the same bile acid (MKHNa), 30 minutes before cardioactive drug infusion. The infusion rate of cardioactive drugs was 0.2 ml/min, except for verapamil (0.1 ml/min). The events observed on ECG recordings were the first myocardial reaction to drug infusion, the second longer-lasting reaction (observed as more extended extrasystoles, decrease in intensity of the QRS complex, or changes in heart rate frequency), and toxicity effect. In the control animals, adrenaline induced a decrease in heart rate frequency at a dose of 0.094 mg/kg, while with stevioside-pretreated rats this effect appeared significantly earlier (at a dose of 0.018 mg/kg). No toxic effect of adrenaline was observed, either in control or stevioside-pretreated group. Bile acids caused no changes in myocardial reaction to adrenaline. Only in the group of animals that received MKHNa, a significant decrease in the QRS complex was observed. Finally, the infusion of stevioside to intact animals at doses of 45 and 55 mg/kg caused no significant changes in the ECG patterns. The myocardial reaction to metoprolol remained unchanged in rats of all groups when compared with controls except for a mild decrease in heart rate frequency. Stevioside inducedproduced a significant increase in myocardial sensitivity to verapamil, but no toxic effect was observed in any of the cases. A similar conclusion also holds for the interaction with MKHNa, whereas ME caused an increase in the toxicity of verapamil.

Joint effect of commercial preparations ofStevia rebaudiana Bertoni and sodium monoketocholate on glycemia in mice

SummaryA study was made of the combined effect of two commercial products of Stevia rebaudiana Bertoni and sodium monoketocholate (mkc) on blood glucose concentration in mice. One group of animals was treated four days with mkc, 4 mg/kg, s. c, second with 200 mg/kg, i. p. , of Stevita (Stevita Co, INC, Arlington, Texas) (stevia), third with 20 mg/kg, i. p. , of Clear Steviosides Liquid (Stevita Co, INC, Herbal supplement, Brazil) (stevioside), fourth with the combination of stevia and mkc, and the fifth with stevisode and mkc. Blood glucose concentration was measured before treatment, after the first and fourth dose, as well as after subjecting animals to glucose-tolerance test (500 mg/kg, p. o. ) or provoking glycemia by injecting adrenaline (0. 2 mg/kg, s. c). It was found that one dose of stevioside combined with mkc caused a significant increase of glycemia with respect of mkc alone and control (10. 80:7. 90:8. 01). However, when repeated four days, the same pretreatment resulted in a significant decrease of glycemia compared with single-dose pretreatment (10. 80:7. 20). The increase in glycemia with the mice that received four doses of stevioside and mkc and then were subjected to glucose-tolerance test was significantly lower compared to that in mice that were pretreated four days only with mkc before receiving glucose (6. 33:7. 80). Analogous difference was observed between the animals given mkc alone and mkc plus stevioside after injecting adrenaline ( 13. 33:10. 54). As for the interaction of mkc and stevia it was found that the combined pretreatment yielded lower values of glycemia compared with that measured after treatment with stevia alone (6. 40:7. 82).

Effects of pharmaceutical formulations containing thyme on carbon tetrachloride-induced liver injury in rats

BackgroundHerbal supplements are widely used in the treatment of various liver disases, but some of them may also induce liver injuries. Regarding the infuence of thyme and its constituents on the liver, conflicting results have been reported in the literature. The objective of this study was to examine the influence of two commonly used pharmaceutical formulations containing thyme (Thymus vulgaris L.), tincture and syrup, on carbon tetrachloride-induced acute liver injury in rats.MethodsChemical composition of investigated formulations of thyme was determined by gas chromatography and mass spectrometry. Activities of enzyme markers of hepatocellular damage in serum and antioxidant enzymes in the liver homogenates were measured using the kinetic spectrophotometric methods. Liver morphology was characterized by light microscopy using routine hematoxylin and eosin staining.ResultsThymol was found to be predominant active constituent in both tincture and syrup. Investigated thyme preparations exerted antioxidant effects in liver by preventing carbon tetrachloride-induced increase of lipid peroxidation. Furthermore, co-treatment with thyme preparations reversed the activities of oxidative stress-related enzymes xanthine oxidase, catalase, peroxidase, glutathione peroxidase and glutathione reductase, towards normal values in the liver. Hepatotoxicity induced by carbon tetrachloride was reflected by a marked elevation of AST and ALT activities, and histopathologic alterations. Co-administration of thyme tincture resulted in unexpected exacerbation of AST and ALT values in serum, while thyme syrup managed to reduce activites of aminotransferases, in comparison to carbon tetrachloride-treated animals.ConclusionsDespite demonstrated antioxidant activity, mediated through both direct free radical scavenging and activation of antioxidant defense mechanisms, thyme preparations could not ameliorate liver injury in rats. Molecular mechanisms of diverse effects of thyme preparations on chemical-induced hepatotoxicity should be more in-depth investigated.

The activity of liver oxidative enzymes after single and multiple grapefruit juice ingestion

In the recent time, several in vitro and in vivo studies have shown the inhibitory effect of grapefruit juice on metabolism of xenobiotics catalyzed by liver oxidative enzymes including cytochrome P450 izoenzymes. However, all these experiments were done with a single dose of grapefruit juice. The primary aim of this study was to evaluate if the chronical ingestion of grapefruit juice can cause enzyme activity alteration as well as a single dose. Three groups of male mice were used: the control group, the group which was administered 0.2 mL of grapefruit juice per os 10 days and the group which was administered single dose of 0.5 mL grapefruit juice per os 90 min. before the sacrificing. After the sacrificing of animals, liver was homogenized with appropriate buffer, and the activity of oxidative liver enzymes: xanthine oxidase (XOD), peroxidase (Px), catalase (CAT), lipid peroxidase (LPx), glutathion peroxidase (GSH-Px) and liver glutathion contents (GSH) were detected by standard methods. The results show that the enzyme activity of liver MFO was changed according to a single or multiple grapefruit juice ingestion. The grapefruit juice in a single oral dose significantly decreases the activity of xanthine oxidase, glutathion peroxidase, lipid peroxidase and liver glutathion contents, and has no effect on activity of catalase and peroxidase. The multiple grapefruit ingestion increases the activity of XOD, GSH-Px, LPx, Px and GSH, while the activity of CAT enzyme is unchanged. The chronical and single grapefruit ingestion has no effect on relative liver weight, but the liver protein content is significantly decreased after the multiple oral grapefruit juice ingestion.

Interaction of alcoholic extracts of hops with pentobarbital and diazepam in mice.

SummaryThe interaction of alcoholic extracts of Magnum, Aroma and wild genotype hops with drugs that lower the activity of the central nervous system (CNS) was studied in mice. Hops drying and preparation of extracts were performed according to standard pharmacological procedures for preparing total alcoholic extracts of medicinal plants, i.e. in a ratio of one part dry herbs to two parts of 70% alcohol, with evaporation to dryness so that the extracts no longer contained any alcohol. The mice received four doses intraperitoneally (i.p.) of 0.5% aqueous solutions of the above-mentioned extracts, which were dissolved in warm physiological solution to make up a 0.5% aqueous solution, 24, 16, 4 and 0.5 hours before pentobarbital (40 mg/kg) or diazepam (3 mg/kg) administration. The hypnotic action of pentobarbital and the effect of diazepam on the coordination of movements (rotating rod method) were measured. It was found that hops extracts influenced the action of the investigated drugs, and that the extracts of the Magnum and Aroma genotypes suppressed the hypnotic action of pentobarbital and diazepam.Terr-butanolic extracts also suppressed the action of these two drugs but to a lesser extent, whereas wild hops extracts did not exert any significant effects compared to controls.