Studies on the activity of bepridil as a scavenger of free radicals

Suppression of Metastatic Ovarian Cancer Cells by Bepridil, a Calcium Channel Blocker

Although surgery followed by platinum-based therapy is effective as a standard treatment in the early stages of ovarian cancer, the majority of cases are diagnosed at advanced stages, leading to poor prognosis. Thus, the identification of novel therapeutic drugs is needed. In this study, we assessed the effectiveness of bepridil-a calcium channel blocker-in ovarian cancer cells using two cell lines: SKOV-3, and SKOV-3-13 (a highly metastatic clone of SKOV-3). Treatment of these cell lines with bepridil significantly reduced cell viability, migration, and invasion. Notably, SKOV-3-13 was more sensitive to bepridil than SKOV-3. The TGF-β1-induced epithelial-mesenchymal transition (EMT)-like phenotype was reversed by treatment with bepridil in both cell lines. Consistently, expression levels of EMT-related markers, including vimentin, β-catenin, and Snail, were also substantially decreased by the treatment with bepridil. An in vivo mouse xenograft model was used to confirm these findings. Tumor growth was significantly reduced by bepridil treatment in SKOV-3-13-inoculated mice, and immunohistochemistry showed consistently decreased expression of EMT-related markers. Our findings are the first to report anticancer effects of bepridil in ovarian cancer, and they suggest that bepridil holds significant promise as an effective therapeutic agent for targeting metastatic ovarian cancer.

Eleusine indica L. possesses antioxidant activity and precludes carbon tetrachloride (CCl₄)-mediated oxidative hepatic damage in rats

OBJECTIVES

The purpose of this study was to evaluate the ability of aqueous extract of Eleusine indica to protect against carbon tetrachloride (CCl₄)-induced hepatic injury in rats.

METHODS

The antioxidant activity of E. indica was evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. The total phenolic content of E. indica was also determined. Biochemical parameters [e.g. alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), glutathione (GSH), catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase and quinone reductase] were used to evaluate hepatic damage in animals pretreated with E. indica and intoxicated with CCl₄. CCl₄-mediated hepatic damage was also evaluated by histopathologically.

RESULTS

E. indica extract was able to reduce the stable DPPH level in a dose-dependent manner. The half maximal inhibitory concentration (IC₅₀) value was 2350 μg/ml. Total phenolic content was found to be 14.9 ± 0.002 mg/g total phenolic expressed as gallic acid equivalent per gram of extract. Groups pretreated with E. indica showed significantly increased activity of antioxidant enzymes compared to the CCl₄-intoxicated group (p < 0.05). The increased levels of serum ALT and AST were significantly prevented by E. indica pretreatment (p < 0.05). The extent of MDA formation due to lipid peroxidation was significantly reduced (p < 0.05), and reduced GSH was significantly increased in a dose-dependently manner (p < 0.05) in the E. indica-pretreated groups as compared to the CCl₄-intoxicated group. The protective effect of E. indica was further evident through decreased histopathological alterations in the liver.

CONCLUSION

The results of our study indicate that the hepatoprotective effects of E. indica might be ascribable to its antioxidant and free radical scavenging property.

Protective effect of partially purified 35 kDa protein from silk worm (Bombyx mori) fecal matter against carbon tetrachloride induced hepatotoxicity and in vitro anti-viral properties

CONTEXT

It has been found that many proteins from silkworm (Bombyx mori L.) fecal matter have been active against human immunodeficiency virus, Sendai virus, herpes simplex virus type-1, and nuclear polyhedrosis virus.

OBJECTIVE

A partially purified 35 kDa protein from silkworm was screened for its hepatoprotective activity, and in vitro antioxidant, and antiviral properties against camelpox and goatpox viruses.

MATERIALS AND METHODS

The study investigated the efficiency of the partially purified 35 kDa protein from silk worm fecal matter against CCl₄-induced liver damage measured in terms of enzyme levels such as aspartate aminotransferase (AST), alanine amino transferase(ALT), alkaline phosphatase (ALP) and total bilirubin, which maintain liver integrity. In vitro antioxidant potential of this protein was determined based on its ability to scavenge 2, 2-diphenylpicrylhydrazyl (DPPH) and superoxide anions scavenging activity. Further, in vitro cytotoxic effect on Vero cells and antiviral activity against goatpox and camelpox viruses were also studied.

RESULTS

The protein had significant hepatoprotection against CCl₄-induced liver damage and scavenging of DPPH radical and superoxide anion activity. However, the protein did not inhibit the multiplication of either virus tested at its maximum non-toxic concentration (MNTC) in vitro.

DISCUSSION AND CONCLUSION

The partially purified 35 kDa protein from silk worm Bombyx mori L fecal matter possessed protective effect against CCl₄-induced oxidative stress in rat model. The protein was found to be ineffective against camelpox and goatpox viruses at its MNTC in vitro.

Potent hepatoprotective effect in CCl(4)-induced hepatic injury in mice of phloroacetophenone from Myrcia multiflora

Background

This study investigated the hepatoprotective effect and antioxidant properties of phloroacetophenone (2′,4′,6′-trihydroxyacetophenone – THA), an acetophenone derived from the plant Myrcia multiflora.

Material & Method

The free radical scavenging activity in vitro and induction of oxidative hepatic damage by carbon tetrachloride (CCl₄) (0.5 ml/kg, i.p.) were tested in male Swiss mice (25±5 g).

Results

This compound exhibited in vitro antioxidant effects on FeCl₂–ascorbate-induced lipid peroxidation (LPO) in mouse liver homogenate, scavenging hydroxyl and superoxide radicals, and 2,2-diphenyl-1-picrylhydrazyl. The in vivo assays showed that THA significantly (p<0.01) prevented the increases of hepatic LPO as measured by the levels of thiobarbituric acid-reactive substances, mitochondrial swelling. It also protected hepatocytes against protein carbonylation and oxidative DNA damage. Consistent with these observations, THA pre-treatment normalized the activities of antioxidant enzymes, such as catalase, glutathione peroxidase, and superoxide dismutase, and increased the levels of reduced glutathione (GSH) in CCl₄-treated mice. In addition, THA treatment significantly prevented the elevation of serum enzymatic activities of alanine amino transferase, aspartate amino transferase, and lactate dehydrogenase, as well as histological alterations induced by CCl₄. Silymarin (SIL) (24 mg/kg), a known hepatoprotective drug used for comparison, led to a significant decrease (p<0.01) in activities of theses enzymes in way very similar to that observed in pre-treatment with THA.

Conclusion

These results suggest that the protective effects are due to reduction of oxidative damage induced by CCl₄ resulting from the antioxidant properties of THA.

Antioxidant and hepatoprotective activity of ethanolic and aqueous extracts of Momordica dioica Roxb. leaves

In present study, the hepatoprotective activity of ethanolic and aqueous extracts of Momordica dioica Roxb. leaves were evaluated against carbon tetrachloride (CCl4) induced hepatic damage in rats. The extracts at dose of 200mg/kg were administered orally once daily. The substantially elevated serum enzymatic levels of serum glutamate oxaloacetate transaminase (AST), serum glutamate pyruvate transaminase (ALT), serum alkaline phosphatase (SALP) and total bilirubin were restored towards normalization significantly by the extracts. Silymarin was used as standard reference and exhibited significant hepatoprotective activity against carbon tetrachloride induced haptotoxicity in rats. The biochemical observations were supplemented with histopathological examination of rat liver sections. The results of this study strongly indicate that Momordica dioica Roxb. leaves have potent hepatoprotective action against carbon tetrachloride induced hepatic damage in rats. Ethanolic extract was found more potent hepatoprotective. Meanwhile, in vivo antioxidant and free radical scavenging activities were also screened which were positive for both ethanolic and aqueous extracts. This study suggests that possible mechanism of this activity may be due to free radical-scavenging and antioxidant activities which may be due to the presence of flavonoids in the extracts.

Bepridil Reverses Atrial Electrical Remodeling and L-Type Calcium Channel Downregulation in a Canine Model of Persistent Atrial Tachycardia

INTRODUCTION

This study tested whether bepridil, a multichannel blocker, would reverse electrical remodeling induced by persistent atrial tachycardia.

METHODS AND RESULTS

Fourteen dogs were subjected to rapid atrial pacing at 400 bpm for 6 weeks after atrioventricular block was created to control the ventricular rate. During the study period, seven dogs were given placebo for 6 weeks (Control group), and seven were given placebo for 3 weeks, followed by 3 weeks of bepridil (10 mg/kg/day, Bepridil group). The atrial effective refractory period (ERP) and the inducibility and duration of atrial fibrillation (AF) were determined on a weekly basis. After 6 weeks, expression of L-type calcium channel alpha1C messenger ribonucleic acid (mRNA) was quantified by real-time reverse transcription-polymerase chain reaction. In the Control group, ERP was shortened and the inducibility and duration of AF increased through the 6-week period. In the Bepridil group, the same changes occurred during the first 3 weeks, but were gradually reversed with bepridil. After 6 weeks, ERP was longer, AF inducibility was lower, and AF duration was shorter in Bepridil group than in the Control group. Expression of alpha1C mRNA was decreased by 64% in the Control group (P < 0.05 vs sham), but in the Bepridil group, it was not different compared with the sham dogs. As a whole group of dogs, ERP was positively correlated with alpha1C mRNA expression.

CONCLUSION

Bepridil reverses the electrophysiological consequences of atrial remodeling to some extent and L-type calcium channel downregulation in a canine model of atrial tachycardia.

Free-radical scavenging by Ouratea parviflora in experimentally-induced liver injuries

The antioxidant potential of crude extracts and fractions from leaves of Ouratea parviflora, a Brazilian medicinal plant used for the treatment of inflammatory diseases, was investigated in vitro through the scavenging of radicals 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydroxyl radical (HO*), superoxide anion (O2*-), and lipid peroxidation in rat liver homogenate. The crude extract (CEOP) and hydro-alcoholic fraction (OP4) showed strong inhibitory activity toward lipid peroxidation induced by tert-butyl peroxide (IC50 = 2.3 +/- 0.2 and 1.9 +/- 0.1 microg/ml, respectively). The same products exhibited a strong concentration-dependent inhibition of deoxyribose oxidation (14.9 +/- 0.2 and 0.2 +/- 0.1 microg/ml, respectively), and also showed a considerable antioxidant activity against O2*- (87.3 +/- 0.1 and 73.1 +/- 0.4 microg/ml, respectively) and DPPH radicals (55.4 +/- 0.3 and 38.3 +/- 0.4 microg/ml, respectively). The protective effects of CEOP and OP4 were also studied in mouse liver. CCl4 significantly increased (by 90%) levels of lipid hydroperoxides, carbonyl protein content (64%), DNA damage index (133%), aspartate aminotransferase (261%), alanine aminotransferase (212%), catalase activity (23%), and also caused a decrease of 60% in GSH content. The results showed that CEOP and OP4 exerted cytoprotective effects against oxidative injury caused by CCl4 in rat liver, probably related to the antioxidant activity showed by the in vitro free radical scavenging property.

Hepatoprotective and free radical scavenging effects of Nelumbo nucifera

Ethanol extracts from Nelumbo nucifera (ENN) seeds were studied for possible antioxidative and hepatoprotective effects. Antioxidative effects were measured spectrophotometrically by reduction of 2,2'-Diphenyl-1-picrylhydrazyl (DPPH) radicals. Hepatoprotective effects were tested using carbon tetrachloride (CCl4) and aflatoxin B1 (AFB1)-induced hepatocyte toxicity models. ENN showed potent free radical scavenging effects with a median inhibition concentration of 6.49 microg/ml. Treatment of hepatocytes with ENN inhibited both the production of serum enzymes and cytotoxicity by CCl4. The genotoxic and cytotoxic effects of AFB1 were also inhibited by ENN in dose-dependent manners. These hepatoprotective effects of ENN against CCl4 and AFB1 might result from its potent antioxidative properties.

2,2'-Diphenyl-1-picrylhydrazyl radical-scavenging active components from adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) hulls

An activity-directed fractionation and purification process was used to identify the antioxidative components of adlay hulls. Hulls of adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) were extracted with methanol and then separated into water, 1-butanol, ethyl acetate, and hexane fractions. The 1-butanol-soluble fraction exhibited greater capacity to scavenge 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radicals when compared with fractions soluble in water, ethyl acetate, and hexane phases. The 1-butanol fraction was then subjected to separation and purification using Diaion HP-20 chromatography, silica gel chromatography, and HPLC. Six compounds showing strong antioxidant activity were identified by spectroscopic methods ((1)H NMR, (13)C NMR, IR, and MS) and by comparison with authentic samples to be coniferyl alcohol (1), syringic acid (2), ferulic acid (3), syringaresinol (4), 4-ketopinoresinol (5), and a new lignan, mayuenolide (6).

Free radical scavenging action of the medicinal herb Limonium wrightii from the Okinawa islands

Free radical scavenging action of Limonium wrightii O. kunthe was examined in vitro and in vivo by using electron spin resonance spectrometer and chemiluminescence analyzer. A water extract of L. wrightii showed a strong scavenging action for the 1,1-diphenyl-2-picrylhydrazyl, or superoxide anion and moderate for hydroxyl radical. The extract also depressed production of reactive oxygen species from polymorphonuclear leukocytes stimulated by phorbor-12-mysistate acetate and inhibited lipid peroxidation in rat liver microsomes. When the extract was given intraperitoneally to mice prior to carbon tetrachloride (CCl4) treatment, CCl4-induced liver toxicity, as seen by an elevation of serum aspartate aminotransferase and alanine aminotransferase activities, was significantly reduced. Gallic acid was identified as the active component of L. wrightii with a strong free radical scavenging action. Our results demonstrate the free radical scavenging action of L. wrightii and that gallic acid contributes to these actions.

Free-radical scavenging action of medicinal herbs from Ghana: Thonningia sanguinea on experimentally-induced liver injuries

The antioxidant action of medicinal herbs used in Ghana for treating various ailments was evaluated in vitro and in vivo. Five plants, Desmodium adscendens, Indigofera arrecta, Trema occidentalis, Caparis erythrocarpus, and Thonningia sanguinea were tested for their free radical scavenging action by their interaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH). Of these five plants, only Thonningia sanguinea was found to scavenge the DPPH radical. Lipid peroxidation in liver microsomes induced by H2O2 was also inhibited by T. sanguinea. The hepatoprotective effect of T. sanguinea was studied on acute hepatitis induced in rats by a single dose of galactosamine (GalN, 400 mg/kg, IP) and in mice by carbon tetrachloride (CCl4, 25 microl/kg, IP). GalN induced hepatotoxicity in rats as evidenced by an increase in alanine aminotransferase (ALT) and glutathione (GSH) S-transferase activities in serum was significantly inhibited when T. sanguinea extract (5 ml/kg, IP) was given to rats 12 hr and 1 hr before GalN treatment. The activity of liver microsomal GSH S-transferase, which is known to be activated by oxidative stress, was increased by the GaIN treatment and this increase was blocked by T. sanguinea pretreatment. Similarly, T. sanguinea pretreatment also inhibited CCl4-induced hepatotoxicity in mice. These data indicate that T. sanguinea is a potent antioxidant and can offer protection against GalN- or CCl4-induced hepatotoxicity.

Structure-property relationships of trimetazidine derivatives and model compounds as potential antioxidants

Twenty-five compounds (trimetazidine derivatives and other compounds, mostly having a free phenolic group) were examined for their radical scavenging and antioxidant properties. Their reaction with DPPH (2,2-diphenyl-1-picrylhydrazyl) as a measure of radical scavenging capacity was assessed by two parameters, namely EC50 (the concentration of antioxidant decreasing DPPH by 50%), and log Z, a kinetic parameter proposed here and derived from initial second-order rate constants and antioxidant/DPPH ratios. Antioxidant activities were determined by the inhibition of lipid peroxidation and albumin oxidation. The most active compounds were derivatives having a trolox or hydroquinone moiety. Physicochemical and structural properties were determined by molecular modeling as lipophilicity (virtual log P calculations) and H-Surf (solvent-accessible surface of hydroxyl hydrogen) and by quantum mechanical calculations (deltaH(ox) = oxidation enthalpy; deltaH(abs) = enthalpy of hydrogen abstraction). QSAR models were derived to identify molecular mechanisms responsible for the reactivity toward the DPPH radical and for the inhibition of lipid peroxidation. A useful prediction of antioxidant capacity could be achieved from calculated molecular properties and the kinetic parameter developed here.

Are the reactive oxygen-derived species (ROS) interactive properties of the many therapeutic drugs from various categories pertinent to their beneficial effects?

Many pathologic states are known to involve the generation of reactive oxygen species, (ROS). It is not known at present to what extent these phenomena are due to ROS formation, or if their formation is a result of the disease. Many therapeutic drugs either scavenge ROS or inhibit their formation. The purpose of this review is to match the drugs used for certain diseases with their anti-ROS actions. This attempted correlation is made to try to give an answer to the title question.

Characterization of drugs as antioxidant prophylactics

There is growing interest in the evaluation of drugs (prescription only medicines and over-the-counter medicines) as antioxidant prophylactics. Although free radical mechanism in human degenerative diseases is now generally recognised, the mechanisms of tissue injury in humans are very complex and it may not be possible to clearly identify the role played by free radicals in the process. This review examines the current evidence to support the notion that drugs for a particular therapeutic category might possess useful antioxidant capacity hence minimising tissue injury due to free radicals.

Antioxidative action of the beta-adrenoceptor antagonist bopindolol and its metabolite 18-502

The antioxidative effects of beta-adrenoceptor antagonists and related compounds were investigated. Among the beta-adrenoceptor antagonists, the agents with a potent membrane-stabilizing activity such as bopindolol and propranolol strongly inhibited the hydrogen peroxide (H2O2)-induced lipid peroxidation of liver microsomes. Fifty percent inhibition concentration values for the lipid peroxidation of bopindolol, 18-502 (metabolite of bopindolol) and propranolol were calculated to be 1.8 microM, 10 microM and 2.3 microM, respectively. The same potency order of the agents for the inhibition of lipid peroxidation was observed in rat heart homogenates. Furthermore, cytochrome P-450-catalyzing lipid peroxidation in microsomes and H2O2-induced lipid peroxidation in coronary arteries or cardiac muscles of pigs were also inhibited by bopindolol, whereas propranolol was less effective. Bopindolol and 18-502, but not propranolol, scavenged a stable free radical 1,1-diphenyl-2-picrylhydrazyl. Thus it was concluded that bopindolol that has membrane-stabilizing and radical scavenging activities is a more potent antioxidant than propranolol and may produce a beneficial effect for the treatment of ischemic cardiac diseases.

Inhibitory effects of calcium antagonists on mitochondrial swelling induced by lipid peroxidation or arachidonic acid in the rat brain in vitro

Inhibitory effects of calcium antagonists, efonidipine (NZ-105), nicardipine, nifedipine, nimodipine and flunarizine, on mitochondrial swelling induced by lipid peroxidation or arachidonic acid in the rat brain in vitro were investigated. Mitochondrial swelling and lipid peroxidation induced by FeSO4 and ascorbic acid system showed a close and significant relationship. Mitochondrial swelling and lipid peroxidation induced by FeSO4 and ascorbic acid were inhibited by all of calcium antagonists tested. The order of inhibition was: flunarizine > nicardipine > efonidipine > nimodipine > nifedipine. This result suggests that calcium antagonists tested have anti-peroxidant activities resulting in protection of mitochondrial membrane damage and that each moiety of these structures would play an important role in appearance of anti-peroxidant activities. Furthermore, flunarizine and efonidipine inhibited mitochondrial swelling induced by arachidonic acid, which is not associated with lipid peroxidation. In contrast, nicardipine, nifedipine, and nimodipine did not inhibited this swelling. It is possible that flunarizine and efonidipine could directly interact with mitochondrial membrane. In conclusion, it is capable that calcium antagonists tested may protect from the membrane damage induced by lipid peroxidation and that flunarizine and efonidipine could stabilize the membrane, which is attributed to a direct interaction with the membrane.

Free radical scavenging and inhibition of lipid peroxidation by beta-blockers and by agents that interfere with calcium metabolism. A physiologically-significant process?

It has been proposed that beta-blockers and agents affecting Ca2+ metabolism might exert cardioprotective actions because of their ability to act as antioxidants in vivo. The feasibility of this proposal was tested by examining the reaction of a series of such compounds with various oxygen-derived species. None of the compounds tested was sufficiently reactive with superoxide radical, hydrogen peroxide or hypochlorous acid for scavenging of these species to be feasible in vivo at the drug concentrations present in patients given the usual therapeutic doses. All the drugs tested were powerful scavengers of hydroxyl radical except for flunarizine, which stimulated iron ion-dependent hydroxyl radical generation from hydrogen peroxide. However, none of the drugs significantly inhibited production of hydroxyl radicals in this system. Propranolol, verapamil and flunarizine had significant inhibitory effects on the peroxidation of rat liver microsomes in the presence of iron ions and ascorbic acid. All three compounds exerted weaker inhibitory effects on peroxidation of arachidonic acid caused by a mixture of myoglobin and H2O2: pindolol stimulated peroxidation in this system. It is concluded that the ability of beta-blockers and "Ca(2+)-blockers" to inhibit lipid peroxidation varies with the lipid substrate used and the mechanism by which peroxidation is induced. We conclude that suggestions that beta-blockers and "Ca(2+)-blockers" exert antioxidant effects in vivo are not well founded, although there is a possibility that verapamil and propranolol might have some inhibitory effects against peroxidation if they accumulate in membranes to a sufficiently-high concentration in vivo. We could not confirm the reported ability of propranolol to inhibit the enzyme xanthine oxidase.