Improving cancer chemotherapy with modulators of ABC drug transporters

ATP-binding cassette (ABC) transporters, P-glycoprotein (P-gp, ABCB1) and ABCG2, are membrane proteins that couple the energy derived from ATP hydrolysis to efflux many chemically diverse compounds across the plasma membrane, thereby playing a critical and important physiological role in protecting cells from xenobiotics. These transporters are also implicated in the development of multidrug resistance (MDR) in cancer cells that have been treated with chemotherapeutics. One approach to blocking the efflux capability of an ABC transporter in a cell or tissue is inhibiting the activity of the transporters with a modulator. Since ABC transporter modulators can be used in combination with chemotherapeutics to increase the effective intracellular concentration of anticancer drugs, the possible impact of modulators of ABC drug transporters is of great clinical interest. Another possible clinical use of modulators that has recently attracted attention is their ability to increase oral bioavailability or increase tissue penetration of drugs transported by the transporters. Several preclinical and clinical studies have been performed to evaluate the feasibility and the safety of this approach. The primary focus of this review is to discuss progress made in recent years in the identification and applicability of compounds that may serve as ABC transporter modulators and the possible role of these compounds in altering the pharmacokinetics and pharmacodynamics of therapeutic drugs used in the clinic.

Imatinib mesylate and nilotinib (AMN107) exhibit high-affinity interaction with ABCG2 on primitive hematopoietic stem cells

The majority of chronic phase chronic myeloid leukemia (CML) patients treated with the tyrosine kinase inhibitor (TKI) imatinib mesylate maintain durable responses to the drug. However, most patients relapse after withdrawal of imatinib and advanced stage patients often develop drug resistance. As CML is considered a hematopoietic stem cell cancer, it has been postulated that inherent protective mechanisms lead to relapse in patients. The ATP binding-cassette transporters ABCB1 (MDR-1; P-glycoprotein) and ABCG2 are highly expressed on primitive hematopoietic stem cells (HSCs) and have been shown to interact with TKIs. Herein we demonstrate a dose-dependent, reversible inhibition of ABCG2-mediated Hoechst 33342 dye efflux in primary human and murine HSC by both imatinib and nilotinib (AMN107), a novel aminopyrimidine inhibitor of BCR-ABL. ABCG2-transduced K562 cells were protected from imatinib and nilotinib-mediated cell death and from downregulation of P-CRKL. Moreover, photoaffinity labeling revealed interaction of both TKIs with ABCG2 at the substrate binding sites as they compete with the binding of [(125)I] IAAP and also stimulate the transporter's ATPase activity. Therefore, our evidence suggests for the role of ABC transporters in resistance to TKI on primitive HSCs and CML stem cells and provides a rationale how TKI resistance can be overcome in vivo.

Meta-analysis: the effects of gut flora modulation using prebiotics, probiotics and synbiotics on minimal hepatic encephalopathy

BACKGROUND

Minimal hepatic encephalopathy (MHE) is characterised by subtle neurocognitive deficits without overt clinical manifestations. Although several trials have individually evaluated the role of prebiotics, probiotics and synbiotics, there is yet no consensus on the management of MHE.

AIM

To estimate the efficacy of prebiotics, probiotics and synbiotics in MHE in randomised controlled trials.

METHODS

MEDLINE, EMBASE, CINAHL and the Cochrane Database of Systematic Reviews were searched for published studies in all languages. Inclusion and exclusion criteria were defined a priori. Pooled relative risk and heterogeneity were estimated as the measures of association.

RESULTS

Nine studies met our inclusion criteria. Use of prebiotics, probiotics and synbiotics significantly reduced the pooled relative risk (RR) of no improvement of MHE (RR 0.40, 95% CI 0.32-0.50; P<0.001). Upon subgroup analysis, five studies with lactulose showed significant reduction of risk of no improvement of MHE (RR 0.34, 95% CI 0.24-0.47; P<0.0001) with no inter-trial heterogeneity. In two trials each of probiotics and synbiotics, their use was associated with significant beneficial effects (RR 0.41, 95% CI 0.26-0.65; P<0.0001 and RR of 0.51, 95% CI 0.32-0.80; P=0.004 respectively). There were no major adverse events though probiotics and synbiotics were better tolerated than lactulose.

CONCLUSIONS

The use of prebiotics, probiotics and synbiotics was associated with significant improvement in minimal hepatic encephalopathy. Among individual agents, lactulose appears to have the most beneficial effect, followed closely by probiotics and synbiotics.

Misdiagnosis of schizophrenia in bipolar patients: a multiethnic comparison

The records of 76 bipolar (DSM-III) patients were reviewed for a history of previous misdiagnosis of schizophrenia. Multivariate analyses identified three variables significantly associated with previous misdiagnosis--auditory hallucinations, early age at onset, and ethnicity. Ethnicity remained significantly associated with misdiagnosis of bipolar patients as schizophrenic even after all other significant variables were partialled out of the equation. It appears from these data that black and Hispanic (Puerto Rican) bipolar patients may be at a higher risk than whites for misdiagnosis as schizophrenic, particularly if they are young and experience auditory hallucinations during affective episodes.

Analyzing the multiple functions of stereotypical behavior for students with autism: implications for assessment and treatment

We studied behavioral functions associated with stereotypical responses for students with autism. In Study 1, analogue functional analyses (attention, demand, no-attention, and recreation conditions) were conducted for 5 students. Results suggested that stereotypy was multiply determined or occurred across all assessment conditions. For 2 students, stereotypy was associated with positive and negative reinforcement and the absence of environmental stimulation. For 2 other students, stereotypy occurred at high levels across all experimental conditions. For the 5th student, stereotypy was associated with negative reinforcement and the absence of environmental stimulation. In Study 2, the stereotypy of 1 student was further analyzed on a function-by-function basis. Within a concurrent-schedules procedure, alternative responses were taught to the student using functional communication training. The results of Study 2 showed that similar topographies of stereotypy, based on qualitatively different reinforcers, were reduced only when differential reinforcement contingencies for alternative forms of communication were implemented for specific response-reinforcer relations. Our results suggest that the causes of stereotypy for students with autism are complex and that the presumed association between response topography and behavioral function may be less important than previously realized.

Lithium-carbamazepine neurotoxicity and risk factors

Five rapid-cycling manic patients developed neurotoxic syndromes when treated with a combination of lithium and carbamazepine, although all five had therapeutic plasma levels of both drugs. The risk factors for development of neurotoxicity with this drug combination are discussed.

Neuroprotective and neurorescue effect of black tea extract in 6-hydroxydopamine-lesioned rat model of Parkinson's disease

In the present study, an attempt has been made to explore the neuroprotective and neuroreparative (neurorescue) effect of black tea extract (BTE) in 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD). In the neuroprotective (BTE + 6-OHDA) and neurorescue (6-OHDA + BTE) experiments, the rats were given 1.5% BTE orally prior to and after intrastriatal 6-OHDA lesion respectively. A significant recovery in d-amphetamine induced circling behavior (stereotypy), spontaneous locomotor activity, dopamine (DA)-D2 receptor binding, striatal DA and 3-4 dihydroxy phenyl acetic acid (DOPAC) level, nigral glutathione level, lipid peroxidation, striatal superoxide dismutase and catalase activity, antiapoptotic and proapoptotic protein level was evident in BTE + 6-OHDA and 6-OHDA + BTE groups, as compared to lesioned animals. BTE treatment, either before or after 6-OHDA administration protected the dopaminergic neurons, as evident by significantly higher number of surviving tyrosine hydroxylase immunoreactive (TH-ir) neurons, increased TH protein level and TH mRNA expression in substantia nigra. However, the degree of improvement in motor and neurochemical deficits was more prominent in rats receiving BTE before 6-OHDA. Results suggest that BTE exerts both neuroprotective and neurorescue effects against 6-OHDA-induced degeneration of the nigrostriatal dopaminergic system, suggesting that possibly daily intake of BTE may slow down the PD progression as well as delay the onset of neurodegenerative processes in PD.

Mania following head trauma

The authors present psychiatric and neurologic data on 20 patients who developed mania after closed head trauma. An association was seen between severity of head trauma (based on length of posttraumatic amnesia), posttraumatic seizure disorder, and type of bipolar disorder. The manic episodes were characterized by irritable mood rather than euphoria and by assaultiveness. Psychosis occurred in only 15% of the sample, and 70% had no depressive episodes. Bipolar disorders were absent among 85 first-degree relatives. The authors suggest that posttraumatic seizures may be a predisposing factor in posttraumatic mania.

Protective effect of Terminalia belerica Roxb. and gallic acid against carbon tetrachloride induced damage in albino rats

Terminalia belerica Roxb. is one of the oldest medicinal herb of India, is an ingredient of Indian Ayurvedic drug 'triphala' used for the treatment of digestion and liver disorders. Present study is aimed to evaluate the protective effect of Terminalia belerica fruit extract and its active principle, gallic acid (3,4,5-trihydroxybenzoic acid) at different doses against carbon tetrachloride intoxication. Toxicant caused significant increase in the activities of serum transaminases and serum alkaline phosphatase. Hepatic lipid peroxidation level increased significantly whereas significant depletion was observed in reduced glutathione level after carbon tetrachloride administration. A minimum elevation was found in protein content on the contrary a significant fall was observed in glycogen content of liver and kidney after toxicant exposure. Activities of adenosine triphosphatase and succinic dehydrogenase inhibited significantly in both the organs after toxicity. Treatment with TB extract (200, 400 and 800mg/kg, p.o.) and gallic acid (50, 100 and 200mg/kg, p.o.) showed dose-dependent recovery in all these biochemical parameters but the effect was more pronounced with gallic acid. Thus it may be concluded that 200mg/kg dose of gallic acid was found to be most effective against carbon tetrachloride induced liver and kidney damage.

Persistent tardive dyskinesia in bipolar patients

The prevalence and outcome of persistent tardive dyskinesia (TD) was studied in 131 bipolar patients. There were 34 cases of persistent TD in the subgroup (n = 96) with a history of neuroleptic treatment (prevalence, 35.4%; 95% confidence interval, 25% to 45%); there were no cases of persistent TD in the subgroup (n = 35) without such treatment history. Except in one patient, signs of TD persisted in spite of lithium carbonate treatment in 23 patients (median duration, 16 months; range, five to 24 months), of whom 15 remained off of a neuroleptic regimen during the study period for a median duration of 14 months (range, four to 24 months). Using multiple regression analysis, two variables were found to predict the presence of persistent TD and account for 36% of the variance: longer cumulative duration of maintenance neuroleptic treatment and shorter duration of previous lithium carbonate treatment. There appears to be a significant risk of persistent TD among neuroleptic-treated bipolar patients. High-risk subgroups within this category need to be identified.

Hepatoprotective potential of Aloe barbadensis Mill. against carbon tetrachloride induced hepatotoxicity

Aloe barbadensis Mill. Syn. Aloe vera Tourn. ex Linn.(Liliaceae) has been used in variety of diseases in traditional Indian system of medicine in India and its use for hepatic ailments is also documented. In the present study an attempt has been made to validate its hepatoprotective activity. The shade dried aerial parts of Aloe barbadensis were extracted with petroleum ether (AB-1), chloroform (AB-2) and methanol (AB-3). The plant marc was extracted with distilled water (AB-4). All the extracts were evaluated for hepatoprotective activity on limited test models as hexobarbitone sleep time, zoxazolamine paralysis time and marker biochemical parameters. AB-1 and AB-2 were observed to be devoid of any hepatoprotective activity. Out of two active extracts (AB-3 and AB-4), the most active AB-4 was studied in detail. AB-4 showed significant hepatoprotective activity against CCl4 induced hepatotoxicity as evident by restoration of serum transaminases, alkaline phosphatase, bilirubin and triglycerides. Hepatoprotective potential was confirmed by the restoration of lipid peroxidation, glutathione, glucose-6-phosphatase and microsomal aniline hydroxylase and amidopyrine N-demethylase towards near normal. Histopathology of the liver tissue further supports the biochemical findings confirming the hepatoprotective potential of AB-4. The present study shows that the aqueous extract of Aloe barbadensis is significantly capable of restoring integrity of hepatocytes indicated by improvement in physiological parameters, excretory capacity (BSP retention) of hepatocytes and also by stimulation of bile flow secretion. AB-4 did not show any sign of toxicity up to oral dose of 2 g/kg in mice.

Treatment of acute herpes zoster: effect of early (< 48 h) versus late (48-72 h) therapy with acyclovir and valaciclovir on prolonged pain

The efficacy of early versus late treatment with acyclovir and valaciclovir on zoster-associated pain was assessed from two databases (1076 patients) that were compiled from randomized trials. Early treatment was started < 48 h and late treatment was started 48-72 h after the onset of cutaneous herpes zoster. Median times to complete resolution of zoster-associated pain were 28 and 62 days, respectively, for patients (> or = 18 years of age) treated with acyclovir and placebo within 48 h (hazard ratio [HR], 1.68; 95% confidence limit [95% CL], 1.19, 2.38) and 28 and 58 days, respectively, for those treated later (HR, 2.20; 95% CL, 1.03, 4.71). In the valaciclovir versus acyclovir study (in patients > or = 50 years of age), the corresponding figures were 44 and 51 days for patients treated early (HR, 1.28; 95% CL, 1.03, 1.60) and 36 and 48 days for those treated later (HR, 1.40; 95% CL, 1.04, 1.87). Acyclovir significantly shortened the time to complete resolution of zoster-associated pain compared with placebo (and valaciclovir was superior to acyclovir in this regard) even when therapy was delayed up to 72 h after rash onset.

Olfactory ensheathing cell transplantation restores functional deficits in rat model of Parkinson's disease: a cotransplantation approach with fetal ventral mesencephalic cells

Different strategies have been worked out to promote survival of transplanted fetal ventral mesencephalic cells (VMCs) using trophic and nontrophic support. Olfactory ensheathing cells (OECs) express high level of growth factors including NGF, bFGF, GDNF, and NT3, which are known to play important role in functional restoration or neurodegeneration. In the present investigation, an attempt has been made to study functional restoration in 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD) following cotransplantation of VMC and OECs (cultured from olfactory bulb, OB) in striatal region. The functional restoration was assessed using neurobehavioral, neurochemical, and immunohistochemical approach. At 12 weeks, post-transplantation, a significant recovery (P < 0.001) in D-amphetamine induced circling behavior (73%), and spontaneous locomotor activity (SLA, 81%) was evident in cotransplanted animals when compared with 6-OHDA-lesioned animals. A significant restoration (P < 0.001) in [3H]-spiperone binding (77%), dopamine (DA) (82%) and 3,4-dihydroxy phenyl acetic acid (DOPAC) level (75%) was observed in animals cotransplanted with OECs and VMC in comparison to lesioned animals. A significantly high expression and quantification of tyrosine hydroxylase (TH)-positive cells in cotransplanted animals further confirmed the supportive role of OECs in viability of transplanted dopaminergic cells, which in turn may be helping in functional restoration. This was further substantiated by our observation of enhanced TH immunoreactivity and differentiation in VMC cocultured with OECs under in vitro conditions as compared to VMC alone cultures. The results suggest that cotransplantation of OECs and VMC may be a better approach for functional restoration in 6-OHDA-induced rat model of Parkinson's disease.

Posterolateral tunnels and ponticuli in human atlas vertebrae

The posterolateral tunnel on the superior surface of the first cervical (atlas) vertebra is of normal occurrence in monkeys and other lower animals, but its presence in the form of a tunnel-like canal, for the passage of the third part of the vertebral artery over the posterior arch of the human atlas vertebra is not reported. The aim of the present study was to detect the presence of such a canal, in addition to other types of ponticuli (little bridges) reported by earlier investigators, in macerated atlas vertebrae and routine cadaveric dissections. The posterolateral tunnel was detected in 1.14%, and the posterior and lateral ponticuli in 6.57 and 2% of vertebrae. Probably the bony roof of the posterolateral tunnel serves the purpose of additional lateral extension for the attachment of the posterior atlanto-occipital membrane in quadrupeds, where the load of the head is supported by the extensor muscles of the neck, ligaments and posterior atlanto-occipital membrane. In man, where the weight of the head is borne by the vertical loading of the superior articular process of the atlas, the roof of the tunnel has disappeared.

The identification of risk factors associated with persistent pain following herpes zoster

Demographic and clinical characteristics of patients with herpes zoster at the time of presentation predict the duration and severity of pain on long-term follow-up. Analyses by Cox's proportional hazard models of six databases from controlled trials of antiviral drugs (total subjects = 2367) identified covariates for zoster-associated pain; all tests for significance were two-sided. Age strongly influenced pain outcome: patients > or = 50 years old were significantly more likely to have prolonged zoster-associated pain compared with those < 30 years old. Patients with prodromal symptoms or moderate or severe pain at presentation were also more likely to experience prolonged zoster-associated pain. Neither time to initiating treatment after rash onset nor sex of patient influenced pain outcome. Advancing age, prodromal symptoms, and acute pain severity at presentation predicted those individuals most at risk of prolonged pain and postherpetic neuralgia. When two or more of these factors were present, the risk of persistent pain was increased.

Factors influencing pain outcome in herpes zoster: an observational study with valaciclovir. Valaciclovir International Zoster Assessment Group (VIZA)

AIM OF THE STUDY

An observational study with valaciclovir was conducted to assess clinical outcome in herpes zoster, especially pain and associated neurological signs and symptoms in relation to a series of demographic and disease characteristics discernible at presentation. The safety and acceptability of valaciclovir for treatment of zoster was assessed in a wide variety of primary care and clinic referral settings.

METHODS

In total, 1897 immunocompetent adults with clinically diagnosed, localized acute herpes zoster were enrolled in this international, open-label study of valaciclovir. All subjects received treatment with oral valaciclovir (1000 mg three times daily) for 7 days from entry to the study and were asked to record the presence of zoster-associated pain and abnormal sensations throughout treatment and 6 months' follow-up. They were seen frequently in clinic to verify subjective assessments and for evaluation of rash healing. Safety and tolerability were assessed by adverse event monitoring.

RESULTS

Overall, 1191 subjects (63%) were aged > or = 50 years, and 203 (11%) had ophthalmic zoster. Cessation of zoster-associated pain was significantly faster in the younger age group; median times to loss of zoster-associated pain were 23 days and 9 days in the > or = 50 and < 50 years age groups, respectively. Similarly, abnormal sensations resolved significantly more rapidly in the younger subjects; the median duration of abnormal sensations was 31 days in the > or = 50 year olds and 16 days in those aged < 50 years. In cases of ophthalmic zoster, the rate of pain resolution was not different from those with zoster in other dermatomes (median duration of pain 18 vs. 16 days). However, abnormal sensations persisted significantly longer in subjects with ophthalmic zoster than in those with zoster at other sites (47 vs. 22 days). In addition to advancing age, subjects suffering moderate to severe prodromal pain or acute pain during the rash phase were at significantly greater risk of zoster-associated pain and abnormal sensations persisting for longer. Subjects with concomitant neurological disorders were also more likely to develop prolonged abnormal sensations. Valaciclovir treatment was well tolerated, and adverse events were rare and generally mild.

CONCLUSION

This study confirmed the prognostic importance of advancing age and the intensity of prodromal or acute pain as risk factors for prolonged zoster-associated pain and persisting abnormal sensations in the affected dermatome. Ophthalmic zoster and pre-existing neurological disorders are also identified as highly significant risk factors for prolonged abnormal sensations in herpes zoster.

Comparative Proteomic Analysis of Aminoglycosides Resistant and Susceptible Mycobacterium tuberculosis Clinical Isolates for Exploring Potential Drug Targets

Aminoglycosides, amikacin (AK) and kanamycin (KM) are second line anti-tuberculosis drugs used to treat tuberculosis (TB) and resistance to them affects the treatment. Membrane and membrane associated proteins have an anticipated role in biological processes and pathogenesis and are potential targets for the development of new diagnostics/vaccine/therapeutics. In this study we compared membrane and membrane associated proteins of AK and KM resistant and susceptible Mycobacterium tuberculosis isolates by 2DE coupled with MALDI-TOF/TOF-MS and bioinformatic tools. Twelve proteins were found to have increased intensities (PDQuest Advanced Software) in resistant isolates and were identified as ATP synthase subunit alpha (Rv1308), Trigger factor (Rv2462c), Dihydrolipoyl dehydrogenase (Rv0462), Elongation factor Tu (Rv0685), Transcriptional regulator MoxR1(Rv1479), Universal stress protein (Rv2005c), 35kDa hypothetical protein (Rv2744c), Proteasome subunit alpha (Rv2109c), Putative short-chain type dehydrogenase/reductase (Rv0148), Bacterioferritin (Rv1876), Ferritin (Rv3841) and Alpha-crystallin/HspX (Rv2031c). Among these Rv2005c, Rv2744c and Rv0148 are proteins with unknown functions. Docking showed that both drugs bind to the conserved domain (Usp, PspA and SDR domain) of these hypothetical proteins and GPS-PUP predicted potential pupylation sites within them. Increased intensities of these proteins and proteasome subunit alpha might not only be neutralized/modulated the drug molecules but also involved in protein turnover to overcome the AK and KM resistance. Besides that Rv1876, Rv3841 and Rv0685 were found to be associated with iron regulation signifying the role of iron in resistance. Further research is needed to explore how these potential protein targets contribute to resistance of AK and KM.

Failure to differentiate bipolar disorder from schizophrenia on measures of neuropsychological function

30 inpatients diagnosed with schizophrenia were compared to 35 inpatients with bipolar affective disorder, manic type, on a large group of neuropsychological measures. Separate factor analyses were performed on measures of verbal, spatial, and speed variables in order to generate summary scales. Controlling for the effects of age, education, sex, duration of illness, number of previous hospitalizations, and medications at time of testing, there were no significant differences between diagnostic groups on the three factors or on individual test variables. Patients on medication performed more poorly on speed variables than those off medication. These findings call into question the notion of differential patterns of cognitive deficit among psychotic diagnoses.

Combination simvastatin and metformin induces G1-phase cell cycle arrest and Ripk1- and Ripk3-dependent necrosis in C4-2B osseous metastatic castration-resistant prostate cancer cells

Castration-resistant prostate cancer (CRPC) cells acquire resistance to chemotherapy and apoptosis, in part, due to enhanced aerobic glycolysis and biomass production, known as the Warburg effect. We previously demonstrated that combination simvastatin (SIM) and metformin (MET) ameliorates critical Warburg effect-related metabolic aberrations of C4-2B cells, synergistically and significantly decreases CRPC cell viability and metastatic properties, with minimal effect on normal prostate epithelial cells, and inhibits primary prostate tumor growth, metastasis, and biochemical failure in an orthotopic model of metastatic CRPC, more effectively than docetaxel chemotherapy. Several modes of cell death activated by individual treatment of SIM or MET have been reported; however, the cell death process induced by combination SIM and MET treatment in metastatic CRPC cells remains unknown. This must be determined prior to advancing combination SIM and MET to clinical trial for metastatic CRPC. Treatment of C4-2B cells with combination 4 μM SIM and 2 mM MET (SIM+MET) led to significant G1-phase cell cycle arrest and decrease in the percentage of DNA-replicating cells in the S-phase by 24 h; arrest was sustained throughout the 96-h treatment. SIM+MET treatment led to enhanced autophagic flux in C4-2B cells by 72–96 h, ascertained by increased LC3B-II (further enhanced with lysosomal inhibitor chloroquine) and reduced Sequestosome-1 protein expression, significantly increased percentage of acidic vesicular organelle-positive cells, and increased autophagic structure accumulation assessed by transmission electron microscopy. Chloroquine, however, could not rescue CRPC cell viability, eliminating autophagic cell death; rather, autophagy was upregulated by C4-2B cells in attempt to withstand chemotherapy. Instead, SIM+MET treatment led to Ripk1- and Ripk3-dependent necrosis by 48–96 h, determined by propidium iodide-Annexin V flow cytometry, increase in Ripk1 and Ripk3 protein expression, necrosome formation, HMGB-1 extracellular release, and necrotic induction and viability rescue with necrostatin-1 and Ripk3-targeting siRNA. The necrosis-inducing capacity of SIM+MET may make these drugs a highly-effective treatment for apoptosis- and chemotherapy-resistant metastatic CRPC cells.

Multiple treatment of propolis extract ameliorates carbon tetrachloride induced liver injury in rats

Propolis, a resinous wax-like beehive product has been used as a traditional remedy for various diseases due to a variety of biological activities of this folk medicine. In the present investigation, an attempt has been made to validate hepatoprotective activity of ethanolic extract of propolis (50-400mg/kg, p.o.) against carbon tetrachloride (CCl(4,) 0.5 ml/kg, p.o.) induced acute liver injury in rats. Silymarin, a known hepatoprotective drug was used as a positive control. Administration of CCl(4) altered various diagnostically important biochemical variables. Multiple treatment of propolis significantly prevented the release of transaminases, alkaline phosphatase, lactate dehydrogenase, gamma-glutamyl transpeptidase, urea and uric acid in serum; improved the activity of hepatic microsomal drug metabolizing enzymes, i.e., aniline hydroxylase and amidopyrine-N-demethylase; significantly inhibited lipid peroxidation and markedly enhanced glutathione in liver and kidney as well as brought altered carbohydrate contents (blood sugar and tissue glycogen), protein contents (serum, microsomal and tissue protein) and lipid contents (serum and tissue triglycerides, serum cholesterol, total and esterified cholesterol in tissue) towards control. Propolis treatment also reversed CCl(4) induced severe alterations in histoarchitecture of liver and kidney in a dose dependent manner. Hepatoprotective activity of propolis at doses of 200 and 400 mg/kg was statistically compared to silymarin and found that propolis exhibited better effectiveness than silymarin in certain parameters, concluded its hepatoprotective potential.