Protective effect of colchiceine against acute liver damage

Antifungal, anticancer, and docking studies of colchiceine complexes with monovalent metal cation salts

Complexes of colchiceine with monovalent cation perchlorates and iodides have been obtained and characterized by spectroscopic methods. DFT and spectroscopic studies reveal that the dihedral angle ω_1-1a-12-12a , crucial for colchicine biological mechanism of action, that is, binding to tubulins depends on the diameter of the complexed metal cation. Biological tests indicated no antifungal properties of colchicine (it was active only toward A.pullulans), in contrast to its derivative-(colchiceine). Complexation of colchiceine with metal cations improved significantly the antifungal potency, even below MIC <1 μg/ml. The colchiceine complexes were more potent than colchiceine, and some of them were even more potent than the fungicidal standard IPBC. The highest potency of colchiceine complexes was noted against A. pullulans (MIC = 0.5 μg/ml). In contrast to the findings concerning antifungal potency, the anticancer studies showed complexes of colchicine more active (~IC₅₀  = 2 nM) than those of colchiceine (~IC₅₀  = 6 μM). MDA-MB-231 breast cancer cell lines and human lung fibroblasts CCD39Lu were also tested.

The effects of grape seed and colchicine on carbon tetrachloride induced hepatic damage in rats

This study aims to determine the effects of grape seed and colchicine on carbon tetrachloride (CCl4) induced hepatic damage and on some serum biochemical parameters. Sixty male Wistar albino rats (200-250 g) were randomly divided into six groups (ten rats/group) and included the control group the group were given isotonic sodium chloride (1 mL/kg b.w) intraperitonealy (i.p.), group 2 the group treated i.p. injection of CCl4 (1.0 mL/kg b.w) in corn oil twice in the first week, Groups 3 and 4 injected with CCl4 as described for group 2 and the rats were orally given (100 mg/kg b.w) GSE and i.p. injected (10 μg/rat) with colchicine for four weeks, respectively and groups 5 and 6 were the grape seed and colchicine control groups in which rats were orally given grape seed (100 mg/kg b.w) and i.p. injected with colchicine (10 μg/rat), respectively. Anorexia, weight loss, motionlessness and hepatic colour variation at necropsy were observed in groups 2, 3, and 4. Hyperemia, focal bleeding, fat degeneration, changes ranging from degenerative to necrotic, increase in connective tissue elements, pronounced in portal sites in particular, and infiltration of lymphoid series cell observed in the livers of the rats in group 2, treated with CCl4. Histological hepatic changes in the rats in group 3 and 4 were similar to those in group 2. The levels of serum total protein, albumin and globulin decreased in groups 2, 3, and 4, compared with groups 1, 5 and 6; aspartate transaminase (ALT) activities increased. The lowest alkaline phosphatase (ALP) activities were in groups 4 and 5. We concluded that GSE and colchicine have not sufficient ameliorative effects to CCl4 induced acute hepatic damage.

Expression and transcriptional activities of nuclear receptors involved in regulation of drug-metabolizing enzymes are not altered by colchicine: focus on PXR, CAR, and GR in primary human hepatocytes

Recent findings show that colchicine (COL) in submicromolar concentrations downregulates the expression of major drug-metabolizing P450 enzymes in human hepatocytes. Concomitantly, the expression of pregnane X receptor (PXR) and constitutive androstane receptor (CAR) was diminished by COL, whereas expression of glucocorticoid receptor (GR) remained unaltered. A tentative mechanism is perturbation of the GR-PXR/CAR-CYP2/3 signaling cascade, resulting in restricted transcriptional activity of GR receptor by colchicine. In this work we focused on 10-demethylcolchicine (colchiceine; EIN), a structural analogue and a putative metabolite of COL that lacks tubulin-binding activity. We investigated the effects of EIN on the expression of PXR, CAR, and GR receptors in primary cultures of human hepatocytes. In contrast with the effects of COL, EIN does not alter the expression of PXR, CAR, and/or GR receptors mRNAs. In addition, EIN had no effects on transcriptional activities of PXR, CAR, and GR receptors in reporter gene assays using transfected cell lines. Considering that COL and EIN are structurally very close and differ only in their tubulin-binding activity, the data presented imply that the deleterious effects of COL on the GR-PXR/CAR-CYP2/3 cascade are primarily due to perturbation of the microtubule network. Our data support the idea of replacing COL by EIN, which is less toxic and does not interact with xenoreceptors.

Optimization of the dose and route of injection, and characterisation of the time course of carbon tetrachloride-induced hepatotoxicity in the rat

INTRODUCTION

The purpose of this study was to optimize carbon tetrachloride-induced hepatotoxicity in the rat with respect to dose, route of injection, and time course.

METHODS

Male Wistar albino rats, 4 to 6 weeks old and weighing 130-180 g were used. Hepatotoxicity was evaluated by measuring the activity of serum enzymes (alkaline phosphatase [ALP], alanine aminotransferase [ALT], and aspartate aminotransferase [AST]) as well as serum total bilirubin level.

RESULTS

Intraperitoneal injection of carbon tetrachloride (CCl(4)) increased the activity of ALP (from 64.9 to 137.3 U/l), ALT (from 106.6 to 693.1 U/l), and AST (from 113.8 to 693.9 U/l). Plasma bilirubin level increased (from 0.119 to 0.42 mg/dl). In contrast, subcutaneous injection of CCl(4) had no effect on these variables. The optimum intraperitoneal dose of CCl(4) was found to be 2 ml/kg body weight (dissolved in an equal volume of olive oil), and this increased the level of bilirubin and the activity of the three enzymes significantly, without causing death of the animals. Hepatotoxicity was observed within 2 h of intraperitoneal injection of CCl(4) and reached a peak after 24 h. Bilirubin level and serum enzyme activities declined gradually to normal levels by 3 days after CCl(4) injection.

CONCLUSION

It is possible to reliably evoke reversible hepatotoxicity in rats by intraperitoneal injection of 2 ml/kg CCl(4).

Comparative effect of colchicine and colchiceine on cytotoxicity and CYP gene expression in primary human hepatocytes

The aims of the present study were (1) to determine the cytotoxicity of colchiceine (EIN) in comparison with that of colchicine (COL); (2) to evaluate the effect of EIN on cytochrome P450 (CYP) expression and activity. Primary human hepatocytes were the model of choice for cytotoxicity and CYP expression experiments. LDH leakage and albumin secretion served as cytotoxicity parameters. EIN was less toxic than COL based on both parameters within the concentration range 1-100 microM. 10 microM concentration of EIN did not induce the expression of CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2E1 and CYP3A4 isoforms, which were evaluated at the levels of mRNAs, proteins and specific activities in culture. EIN in concentrations up to 200 microM had no effect on marker activities of CYP1A2, 2C9, 2E1 and 3A4 in human liver microsomes. It was concluded that EIN in concentrations up to 10 microM is not cytotoxic in primary human hepatocytes as revealed by albumin secretion and LDH leakage. Possible drug-drug interactions of EIN due to effects on cytochromes P4501A2, 2C9, 2E1 and 3A4 isoforms are unlikely because inhibition/induction studies show any lack of such effects. As EIN was shown to have better antifibrotic properties than COL (European Journal of Clinical Investigation 1997, 2, 77), it can be used as a COL substitute with anticipated fewer side-effects.

Biphasic effect of colchicine on acute liver injury induced by carbon tetrachloride or by dimethylnitrosamine in mice

BACKGROUND/AIMS

The effects of colchicine on acute liver injury induced by carbon tetrachloride or by dimethylnitrosamine in mice were examined.

METHODS

Nonlethal acute liver injury was induced in male BALB/c mice by a single intraperitoneal injection of 0.8 ml/kg carbon tetrachloride or 15 mg/kg dimethylnitrosamine. 0.6 mg/kg colchicine was administered 18 h or 2 h intraperitoneally before hepatotoxin treatment.

RESULTS

Reversible centrilobular to mid-zone necrosis and apoptosis occupying half the liver lobular area was evoked by carbon tetrachloride, and dimethylnitrosamine, respectively. Administration of colchicine 18 h before hepatotoxins markedly suppressed liver injury, whereas colchicine administration 2 h before the hepatotoxins accelerated it. The hepatoprotective effect evoked by colchicine was due to reduction in liver cytochrome P450 content and P450 2E1 activity. In contrast, the hepatodestructive effect seen in the carbon tetrachloride model was related to the extent of lipid peroxidation promoting plasma membrane destruction, while the hepatodestructive effect in the dimethylnitrosamine model was due to suppression of Bcl-X(L) expression, leading to acceleration of apoptosis.

CONCLUSIONS

A biphasic effect of colchicine on carbon tetrachloride- and dimethylnitrosamine-induced acute liver injury was seen. The time interval between colchicine administration and the hepatotoxin treatment is crucial to the subsequent development of liver lesions.

Melatonin counteracts lipid peroxidation induced by carbon tetrachloride but does not restore glucose-6 phosphatase activity

Carbon tetrachloride (CCl4) exerts its toxic effects by the generation of free radicals. In this study we investigated whether melatonin, a potent free radical scavenger, could prevent the deleterious effects of CCl4. Liver homogenates and liver microsomes were incubated with CCl4 in the presence of melatonin and lipid peroxidation and glucose-6 phosphatase (G6Pase) activity were determined. All doses of CCl4 (1, 0.5, 0.1 mM) produced significantly high levels of lipid peroxidation, as reflected by increased levels of malonaldehyde and 4-hydroxyalkenals, in both liver homogenates and liver microsomes. These doses of CCl4 concommitantly reduced the activity of microsomal G6Pase. Co-incubation with melatonin dose-dependently (2, 1, 0.5 mM) inhibited the production of lipid peroxidation, but it was unable to restore the activity of G6Pase. In in vivo studies, rats were also treated with melatonin (10 mg/kg, i.p.), given 30 min before and 60 min after the administration of CCl4 (5 ml/kg, i.p.). Significantly elevated levels of lipid peroxidation were measured in the liver and kidney. Melatonin prevented the CCl4-induced lipid peroxidation in the kidney, but not in the liver. These data suggest that melatonin may provide protection against some of the damaging effects of CCl4, possibly due to its ability to scavenge toxic free radicals.

Decrease in hepatotoxicity by lead exposure is not explained by its mitogenic response

The present research was conducted to evaluate the effect of mitogen pre-exposure on CCl4-induced hepatotoxicity. Male Wistar rats were administered a single i.p. injection of CCl4 (0.3 ml kg-1 in corn oil) 48 h following either a single dose of lead nitrate (0.33 mg kg-1) or distilled water via i.v. injection. Hepatotoxicity, as measured by serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, was monitored 6, 24, 48, 72 and 120 h after CCl4 exposure. The lead nitrate-pretreated rats displayed markedly lower serum ALT and AST levels at 24, 48 and 72 h than rats pretreated with distilled water. However, treatment with the antimitotic agent colchicine did not alter the lead-induced protection. These findings suggest that the lead-induced protection is not associated with the major mitogenic response of lead, despite its strong temporal association. A critical review of the available toxicological data also argues against the lead protection being a function of its capacity to inhibit cytochrome P-450.

Role of lipid peroxidation in biliary obstruction in the rat

There is poor evidence about the participation of lipoperoxidative processes in liver damage induced by biliary obstruction, thus the aim of this work was to study the role of lipid peroxidation in this model of liver injury. Biliary obstruction was induced in male Wistar rats by ligation of the common bile duct; control animals were sham operated. Rats were sacrificed at different times after surgery. Liver sections were used for glycogen and lipoperoxidation quantification. Markers of liver damage were determined in serum. All serum markers of liver damage increased after 1 day of biliary obstruction. Liver glycogen content decreased 1 day after surgery. On the other hand, lipoperoxidation increased later than markers of liver damage, suggesting that it is a consequence rather than the cause of liver injury. Moreover, administration of colchiceine (a good free-radical scavenger) or vitamin E prevented lipoperoxidation but not liver damage, confirming that lipoperoxidation does not play an important role in liver damage induced by biliary obstruction. This model of liver injury seems to be useful for testing hepatoprotective drugs that do not act as free-radical scavengers.