Effect of ninhydrin on the biochemical and histopathological changes induced by ethanol in gastric mucosa of rats.

Studies on the effect of ninhydrin in the normal gastric mucosa and against the ethanol induced gastric injury were undertaken in rats in view of the presence of a carbonyl function as well as hydroxyl groups in its chemical structure. In spite of its potentials to generate hydroxyl radicals, it is deemed to possess antioxidant property by virtue of its electrophilic nature. Recent studies have shown gastro-protection to mediate through a reaction between the electrophilic compounds and sulfhydryl groups of the mucosa. Hence it was found worthwhile to evaluate the interaction between the oxidant and antioxidant functions in the structure of the same compound. The effects of ninhydrin pretreatment on gastric mucosal injuries caused by 80% ethanol, 25% NaCl and 0.2M NaOH were investigated in rats. The gastric tissue in ethanol-treated rats was analyzed for different histopathological lesions. In addition, the effects on ethanol-induced changes in the gastric levels of proteins, nucleic acids, non-protein sulfhydryl (NP-SH) and malondialdehyde (MDA) were also evaluated. Ninhydrin, as such, failed to induce any significant changes in normal gastric mucosa, while its pretreatment at oral doses of 5, 10 and 20 mg/kg was found to provide a dose-dependent protection against the ulcers induced by ethanol, NaOH and NaCl. The results of histopathological evaluation revealed a protective effect of ninhydrin on congestion, hemorrhage, edema, erosions and necrosis caused by ethanol. Furthermore, the pretreatment afforded a dose-dependent inhibition of the ethanol-induced depletion of proteins, nucleic acids, NP-SH and increase of MDA in the gastric tissue. The results obtained clearly demonstrate the anti-ulcerogenic activity of ninhydrin. The exact mechanism of action is not known. However, the carbonyl function in ninhydrin appears to achieve antioxidant balance and protect the gastric mucosa from the ethanol-induced gastric injury. Further studies are warranted to investigate the toxicity and detailed mechanism of action of this potent compound before any clinical trials, especially at the effective lower doses.

Inhibition of gastric mucosal damage by methylglyoxal pretreatment in rats.

The effect of methylglyoxal pretreatment on gastric mucosal injuries caused by 80% ethanol, 25% NaCl and 0.2 M NaOH, was investigated in rats. The effects caused by pylorous ligation accumulated gastric acid secretions and ethanol-induced changes in gastric mucus secretions, levels of proteins, nucleic acid, malondialdehyde (MDA) and non-protein sulfhydryl groups were also investigated. Methylglyoxal pretreatment at oral doses of 50, 100 and 200 mg/kg body weight was found to provide a dose-dependent protection against the ulcerogenic effects of different necrotizing agents used. With the same dose regimen methylglyoxal offered significant protection against ethanol-induced damage on the parameters evaluated for histopathology. Furthermore, the pretreatment afforded a dose-dependent inhibition of pylorous ligated accumulation of gastric acid secretions and ethanol-induced depletion of stomach wall mucus, proteins, nucleic acids, NP-SH contents and an increase in the MDA levels in gastric tissue. The protective effect of methylglyoxal against ethanol-induced damage to the gastric wall mucosa may be mediated through its effect on mucous production, proteins, nucleic acids, NP-SH groups and its free-radical scavenging property under the influence of polyamines stimulated by ornithine decarboxylase activity (ODC).

Studies on the cytotoxic, biochemical and anti-carcinogenic potentials of ninhydrin on Ehrlich ascites carcinoma cell-bearing Swiss albino mice.

Ninhydrin (2,2-dihydroxy-1,3-indane dione) was evaluated for its antitumor and cytotoxic properties in Ehrlich ascites carcinoma cell (EAC Cell)-bearing mice. The rationale behind this study has been mainly the literature reports of its characteristic interference with DNA synthesis and calcium homeostasis. Antitumor activity was evaluated from the total count and viability of EAC cells in addition to their nucleic acid, protein, non-protein sulfhydryls (NP-SH) and malondialdehyde (MDA) contents. The EAC cell-bearing animals were also observed for the effect on their survival and body weight variations. In addition, the tumors grown at the site of injection were evaluated for histopathological changes. Ninhydrin treatments (5, 10 and 20 mg/kg/day) abate the increase in body weight and advanced the duration of survival in EAC cell-bearing mice. The results on histopathological investigations show retardation in tumor growth, decreased frequency of mitotic figures and hair follicles and an increased necrosis in the tumor by ninhydrin treatment. Our results on cytotoxicity, which demonstrated compression in the number of EAC cells and their viability substantiate these data. The results of biochemical studies on EAC cells exhibit a reduction in the levels of DNA, RNA, proteins and NP-SH with a subsequent increase in the concentrations of MDA after ninhydrin treatment. Inhibition in tumor growth was dose dependently significant with the same dose regimen. The observed cytotoxic and antitumor activity of ninhydrin was comparable to cyclophosphamide. The possible mode of action of ninhydrin-induced cytotoxic and antitumor activity appear to be due to its interference with mitochondrial function resulting in inhibition of DNA synthesis, an effect that is being investigated further.

Effect of Cremophor EL on the pharmacokinetics, antitumor activity and toxicity of doxorubicin in mice.

Cremophor EL (CR) is a solubilizing agent and a modulator of P-glycoprotein (P-gp)-mediated anticancer multidrug resistance. The present study was undertaken to evaluate whether doxorubicin (Dox) pharmacokinetics, therapeutic activity and cardiotoxicity in Swiss albino mice is modified when combined with CR treatment. CR (2.5 ml/kg, i.p) given simultaneously with Dox (20 mg/kg, i.p.) increased Dox levels in plasma, heart, liver and kidneys of healthy mice. Using an Ehrlich ascites carcinoma (EAC)-bearing mice experimental model, CR (2.5 ml/kg) improved the survival and antitumor activity of Dox. The enhanced antitumor activity of Dox was related to a significant increase in EAC tumor cellular Dox content by CR. Furthermore, CR (1 microg/ml) potentiated the in vitro cytotoxicity of Dox in cultured EAC cells. In healthy mice, Dox-induced mortality was markedly reduced by simultaneous treatment with CR. CR enhanced DOX-induced increase in plasma lactate dehydrogenase, creatine phosphokinase (CPK) and CPK-MB isozyme activities, as well as the cardiac malondialdehyde level. CR also increased Dox-induced focal necrotic myocardial lesions. These findings suggest that CR increased DOX antitumor activity and cardiotoxicity as a result of enhancing its bioavailability, and decreased Dox-induced mortality in mice by a mechanism not yet defined.

Effects of L-histidinol on the antitumour activity and acute cardiotoxicity of doxorubicin in mice.

L-Histidinol (LHL), a structural analogue of the essential amino acid l-histidine, can improve the therapeutic index of antimetabolites and alkylating agents. The objective of the study was to determine whether LHL would modulate the antitumour activity and acute cardiotoxicity of the anthracycline antibiotic, doxorubicin (DOX). LHL (1.0 mM) potentiated the cytotoxicity of DOX (0.05-0.8 microg ml-1) in cultured Ehrlich ascites carcinoma (EAC) cells. LHL (250 mg kg-1, i.p.) administered for five consecutive doses at 2-h intervals starting 2 h before DOX (5 mg kg-1, i.p.) single injection, enhanced the antitumour activity of DOX in EAC-bearing mice as manifested by a significant increase in average life span and cure rate of mice. In normal mice, LHL, in the same dose regimen, could not alter the acute cardiotoxicity and lethality of DOX (10 mg kg-1, i.p.). The present data indicate that LHL may improve the therapeutic efficacy of DOX in EAC-bearing mice without compromising its toxicity. Also, our finding supports the LHL/anticancer drug combination approach.

Thymoquinone protects against doxorubicin-induced cardiotoxicity without compromising its antitumor activity.

Doxorubicin (DOX) has a wide spectrum of antitumor activity with dose-related cardiotoxicity as a major side effect. This cardiotoxicity has been suggested to result from the generation of oxygen-free radicals. The objective of the present study was to investigate the influence of the antioxidant, thymoquinone (TQ) on cardiotoxicity and antitumor activity of DOX in mice. TQ (8 mg/kg/day, p.o.) administered with drinking water starting 5 days before a single i.p. injection of DOX (20 mg/kg) and continuing during the experimental period ameliorated the DOX-induced cardiotoxicity in mice. This finding was evidenced by significant reductions in serum lactate dehydrogenase and creatine kinase elevated levels and further supplemented by histopathological examination of cardiac tissue. TQ did not alter the plasma and heart DOX levels as monitored by fluorometric analysis. In in vivo study on mouse Ehrlich ascites carcinoma tumor, it could then be shown that TQ does not interfere with the antitumor activity of DOX. The current data support TQ as a potentially selective cytoprotective agent, which may ameliorate cardiotoxicity without decreasing DOX antitumor activity.

Effect of probucol on the cytological and biochemical changes induced by adriamycin in Swiss albino mice.

Probucol [(4,4'-(-(isopropylidenedithio) bis (2,6-di-t-butylphenol)], a hypolipidemic drug, was evaluated for its effects on the clastogenic activity of ADM in Swiss albino mice. Male mice were treated i.p. with different doses (25, 50 and 100 mg/kg, body weight/day) of probucol for 7 days. Some of the mice in each dose group of probucol and those in the positive control group were injected i.p. with Adriamycin (ADM, 8 mg/kg, body weight) and killed after 24 hr. Femoral cells of mice were collected and studied for the frequency of micronuclei and the ratio of polychromatic erythrocytes to Normochromatic erythrocytes. Furthermore, proteins, DNA, RNA, Malondialdehyde (MDA) and non-protein sulfhydryl (NP-SH) levels were determined in the hepatic cells. Probucol treatment failed to induce any significant clastogenic, cytotoxic and biochemical changes. However, pre-treatment with probucol was found to reduce the ADM-induced micronuclei without any alteration in its cytotoxicity. The DNA, RNA, proteins and NP-SH levels in the hepatic cells of these animals were increased and the MDA concentrations were reduced. The inhibition of ADM-induced clastogenicity by probucol may be attributed to its lipids lowering, iron chelating, free radical scavenging and topoisomerase-II-depleting action.

Effect of desferrioxamine on cisplatin-induced nephrotoxicity in normal rats.

Biochemical and histological evaluations of the effects of the iron chelator desferrioxamine on the nephrotoxicity induced by cisplatin in normal rats were carried out. A single dose of cisplatin (7.5 mg/kg, intravenously) caused nephrotoxicity that manifested biochemically as an elevation of blood urea nitrogen, serum creatinine and an increase in the kidney weight as a percent of body weight. Moreover, severe decreases in serum calcium and albumin were observed. Histopathological examination of kidney tissue revealed tubular necrosis with sloughing of tubular epithelium. Desferrioxamine treatment (250 mg/kg, intraperitoneally) 30 min before cisplatin administration does not protect the kidney from the damaging effects of cisplatin. A greater increase in blood urea nitrogen, serum creatinine and kidney weight was observed with significant tubular necrosis and a mild lymphocytic infiltrate. Desferrioxamine pretreatment decreased the lipid peroxidation induced by cisplatin but at the same time increased nonprotein sulfhydryl (-SH) concentrations in the kidney tissue. The findings of this study suggest that lipid peroxidation is not the main cause of cisplatin-induced nephrotoxicity and that desferrioxamine which was useful for prevention of cardiac and hematological damage induced by doxorubicin, aggrevated the cisplatin-induced nephrotoxicity. More investigations are needed to establish a definite assessment of its selectivity.

Diltiazem potentiation of doxorubicin cytotoxicity and cellular uptake in Ehrlich ascites carcinoma cells.

The calcium channel blocker diltiazem, which possesses coronary vasodilator activity, greatly enhanced the cytotoxicity of doxorubicin in Ehrlich ascites carcinoma cells. 20% of the doxorubicin-treated tumor-bearing animals (2 mg/kg, every other day, three doses) survived, with a mean survival time of 35 days. However, pretreatment with diltiazem increased survival to 70% with a mean survival time of 43 days. Diltiazem treatment increased the intracellular level of doxorubicin, and there was a good correlation between the high cellular level of doxorubicin and its cytotoxic activity. In tumor-bearing animals pretreated with diltiazem, doxorubicin showed a pronounced inhibitory effect on cellular DNA, RNA content and acid phosphatase activity of tumor cells. In addition, there was a marked increase in cellular cholesterol and lipid contents. This study may suggest the benefit of using diltiazem to potentiate the cytotoxic effect of doxorubicin, allowing its dose and consequently the serious side effects to be reduced.

Effect of acute administration of fish oil (omega-3 marine triglyceride) on gastric ulceration and secretion induced by various ulcerogenic and necrotizing agents in rats.

The fish oil commercially known as Marine-25 (omega-3 marine triglyceride) is an eicosapentaenoic acid (EPA)-rich oil. It was investigated for its ability to inhibit gastric secretion and to protect the gastric mucosa against the injuries caused by pyloric ligation, non-steroidal anti-inflammatory drugs (NSAIDs--aspirin and indomethacin), reserpine, hypothermic restraint stress and necrotizing agents [0.6 M HCl 0.2 M NaOH or 80% (v/v) aqueous ethanol]. The results showed that the fish oil, at a dose of 5 or 10 ml/kg body weight, provided significant protection in the various experimental models used. It produced a significant inhibition of gastric mucosal damage induced by pyloric ligation, NSAIDs, reserpine or hypothermic restraint ulcers. Fish oil also exerted a significant inhibitory action on gastric mucosal lesions produced by various necrotizing agents. Our findings show that fish oil rich in eicosapentaenoic acid possesses both antisecretory and antiulcerogenic effects.

Enhancement of doxorubicin-induced cytotoxicity by hyperthermia in Ehrlich ascites cells.

Hyperthermia (HPT) at 43 degrees C for 30 min increased the cytotoxic activity of doxorubicin against the growth of Ehrlich ascites carcinoma cells. There was more delay in tumor growth with 89% inhibition in the tumor volume and 90% increase in the survival of the tumor-bearing animals compared to control group. Combination of HPT with doxorubicin showed a more pronounced inhibitory effect on tumor content of DNA, RNA, protein, cholesterol, total lipid and acid phosphatase activity. HPT did not significantly affect the doxorubicin uptake into tumor cells, but it has some inhibitory effect on some vital components. Along with other results, our data suggest the benefit of using HPT to enhance the cytotoxic activity of doxorubicin with a consequent reduction of doxorubicin dose and hence a decrease of its serious side effects.

Evaluation of teratogenic potential of khat (Catha edulis Forsk.) in rats.

The embryotoxic and teratogenic effects of khat (Catha edulis Forsk.), a plant chewed by the people of Eastern Africa and Southern Arabia to attain a state of euphoria and stimulation, was studied in Wistar rats. Methanolic extract of khat was administered orally by gavage to rats during days from 6 to 15 of gestation at doses of 0, 125, 250 and 500 mg/kg. body weight/day. Khat reduced the food consumption and maternal weight gain and also lowered the food efficiency index, as compared to control mothers. On day 20 of gestation, all dams were sacrificed by cervical dislocation, cesarean sections were performed and maternal and fetal toxicities were assessed. The administration of khat had no effect on fetal sex ratio. However, at a dose of 125 mg/kg body weight and above, it produced a significant increase in resorptions and fetal wastage. Khat administration in utero also reduced the litter size and caused intrauterine growth retardation. External, visceral and skeletal examination of the fetus of treated dams showed several types of malformations and variations in all the groups of animals. However, a consistent tendency of abnormalities was observed in the highest dosed (500 mg/kg) group. The data of the present study revealed that khat retarded fetal growth and induced terata. The present observations indicate that khat possesses both embryotoxic as well as teratogenic properties. The developmental toxicities of khat are dose-related.

Potentiation of doxorubicin cytotoxicity by the calcium channel blocker verapamil in Ehrlich ascites cells.

The calcium channel blocker verapamil increased the intracellular level of doxorubicin in Ehrlich ascites cells. The high cellular drug level was directly related to the enhancement of the cytotoxicity of the antitumor agent. Tumor-bearing mice pretreated with verapamil showed a 2.3-fold increase in long-term survival effect of doxorubicin together with a pronounced inhibitory effect on tumor DNA, RNA and protein content. This study suggests the possible novel use of verapamil to enhance the antitumor activity of doxorubicin, allowing its dose, and consequently the serious side effects, to be reduced.

The effect of maternal administration of enalapril on fetal development in the rat.

Enalapril (MK, 421), an angiotensin converting enzyme inhibitor, was tested for teratogenicity using Wistar rats. The drug was given by oral intubation, from 6-15 days of gestation, at the doses of 0, 3, 10 and 30 mg/kg/day. Reduction in body weight and food consumption were observed in the treated dams. However, food efficiency index, assessed at different periods of gestation was found to be unaffected. On day 20 of gestation, all the dams were sacrificed by cervical dislocation and sign of maternal toxicity, reproduction indices and fetal measures were recorded. The dams treated with enalapril at only the doses of 10 and 30 mg/kg, produced significant decrease in numbers of implants, litter size and incidence of reabsorbed fetuses, and also reduced neonatal growth. No such effects were observed at the lowest dose level (3 mg/kg) used. External, visceral and skeletal examinations of the fetuses of enalapril-treated dams showed several types of variations in all groups, but no consistent pattern were observed. However, a slight increase in skeletal variations was seen with the highest dose (30 mg/kg) group. The data of the present study under the conditions described herein and at the doses employed, revealed no evidence of teratogenesis, but numerous deleterious effects on the fetus were evident.

Prevention of doxorubicin-induced myocardial and haematological toxicities in rats by the iron chelator desferrioxamine.

Biochemical and histopathological evaluations of the protective effects of the iron-chelator desferrioxamine against the cardiac and haematological toxicities of doxorubicin in normal rats were carried out. A single dose of doxorubicin (15 mg/kg, i.v.) caused myocardial damage that manifested biochemically as an elevation of serum cardiac enzyme [glutamic oxaloacetic transaminase (GOT), lactic dehydrogenase (LDH) and creatine phosphokinase (CPK)] and cardiac isoenzyme levels and histopathologically as a swelling and separation of cardiac muscle fibers. Doxorubicin caused severe leucopenia and decreases in red blood cell counts and haemoglobin concentrations at 72 h after its administration. Desferrioxamine treatment (250 mg/kg, i.p.) carried out 30 min before doxorubicin administration protected the heart and blood elements from the toxic effects of doxorubicin as indicated by the recovery of levels of cardiac enzymes and isoenzymes and of red blood cell counts to normal values and by the absence of significant myocardial lesions. The findings of this study suggest that desferrioxamine can potentially be used clinically to prevent doxorubicin-induced cardiac and haematological toxicities.