Modulation of 7,12-dimethylbenz[a]anthracene-induced transmammary carcinogenesis by disulfiram and butylated hydroxyanisole in mice

Chemomodulatory action of Aloe vera on the profiles of enzymes associated with carcinogen metabolism and antioxidant status regulation in mice

The effect of two doses (30 microl and 60 microl/day/mice daily for 14 days) of the fresh leaf pulp extract of Aloe vera was examined on carcinogen-metabolizing phase-I and phase-II enzymes, antioxidant enzymes, glutathione content, lactate dehydrogenase and lipid peroxidation in the liver of mice. The modulatory effect of the pulp extract was also examined on extrahepatic organs (lung, kidney and forestomach) for the activities of glutathione S-transferase, DT-diophorase, superoxide dismutase and catalase. The positive control mice were treated with butylated hydroxyanisole (BHA). Significant increases in the levels of acid soluble sulfhydryl (-SH) content, NADPH-cytochrome P450 reductase, NADH-cytochrome b5 reductase, glutathione S-transferase (GST), DT-diaphorase (DTD), superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX) and glutathione reductase (GR) were observed in the liver. Aloe vera significantly reduced the levels of cytochrome P450 and cytochrome b5. Thus, Aloe vera is clearly an inducer of phase-II enzyme system. Treatment with both doses of Aloe caused a decrease in malondialdehyde (MDA) formation and the activity of lactate dehydrogenase in the liver, suggesting its role in protection against prooxidant-induced membrane and cellular damage. The microsomal and cytosolic protein was significantly enhanced by Aloe vera, indicating the possibility of its involvement in the induction of protein synthesis. BHA, an antioxidant compound, provided the authenticity of our assay protocol and response of animals against modulator. The pulp extract was effective in inducing GST, DTD, SOD and catalase as measured in extrahepatic organs. Thus, besides liver, other organs (lung, kidney and forestomach) were also influenced favorably by Aloe vera in order to detoxify reactive metabolites, including chemical carcinogens and drugs.

Chemoprevention of DMBA-induced transplacental and translactational carcinogenesis in mice by oil from mustard seeds (Brassica spp.)

The present study reports the chemopreventive potential of the oil from mustard seed on 7,12-dimethylbenz[a]anthracene-induced transplacental and translactational carcinogenesis in Swiss albino mice. Gestating females were treated with mustard oil at dose levels of 0.05 and 0.10 ml per day from days 13 to 19 of gestation. In addition, they were given DMBA (3 mg/animal) on days 15-17 of gestation. The percentage of tumour incidence in the F1 progeny was reduced significantly at both dose levels from 65% in the control group to 29% and 16%, respectively, in the experimental groups. The mean number of tumours per effective F1 progeny was reduced from 1.56 in the control group to 0.93 and 0.41 in the animals treated with lower and higher doses of mustard oil, respectively. When lactating mothers were given the mustard oil at dose levels of 0.05 and 0.10 ml per day for the first 15 days of lactation in addition to DMBA given on days 3, 6, 9, 12 and 15 of lactation, the multiple site tumour incidence was brought down significantly from a control value of 70% to 32% and 18%, respectively, in lower and higher dose groups. The mean number of tumours in the F1 mouse was reduced from a control value of 1.71 to 0.96 at the lower dose level and to 0.34 at the higher dose level. From earlier studies done in our laboratory, it appears that mustard oil exerts its effect by inducing the enzymes of drug detoxification and also by changing the profile of the antioxidant defence system. The quantitative and qualitative nature of the active principles and their passage into the F1 progeny remains to be seen.

Postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract in the detoxication pathway of suckling neonates and lactating mice

The present study evaluates the postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract via assessing the modulation in the biotransformation system enzymes of suckling neonates and lactating mice. The peel, seed or whole fruit extract of Momordica (100 microl/animal/day) independently induced a significant increase in the hepatic levels of glutathione S-transferase (GST) and acid soluble sulfhydryl (-SH) after 14 or 21 days treatment in lactating dams (P < 0.01) and translactationally exposed neonates (P < 0.05). However, the elevation (P < 0.05) in hepatic cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) levels was observed only in the lactating dams treated with the respective extracts of peel, seed or whole fruit of Momordica. In lactating dams and suckling neonates the modulated levels of biotransformation system enzymes suggest the potential for the translactational passage of active principle(s) and/or metabolites of Momordica.

Postnatal effect of smokeless tobacco on phytic acid or the butylated hydroxyanisole-modulated hepatic detoxication system and antioxidant defense mechanism in suckling neonates and lactating mice

The present study evaluates the potential of smokeless tobacco to translactationally modify the chemopreventive efficacy of phytic acid and butylated hydroxyanisole (BHA) via modulation of the hepatic xenobiotic detoxication system and antioxidant defense mechanism in the murine system. Phytic acid (1000 mg/kg b.w./day) by gavage while BHA (1% w/w) in diet induced a significant increase in the levels of glutathione-S-transferase (GST), acid soluble sulfhydryl (-SH), cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) in lactating dams and suckling pups. The hepatic levels of GST and -SH were significantly depressed whereas microsomal Cyt. b5, Cyt. P-450 and MDA levels were elevated in groups treated with smokeless tobacco (50 or 100 mg/kg b.w./day). The data reveals the inhibitory potential of smokeless tobacco on phytic acid-induced GST/GSH system efficiency besides the significant augmentation by smokeless tobacco on phytic acid or BHA-induced microsomal phase I enzymes. The direct or translactational modulation in the levels of xenobiotic detoxication system enzymes suggests the potential of smokeless tobacco to modify the chemopreventive efficacy of phytic acid or BHA.

Modulatory influence of arecoline on the phytic acid-altered hepatic biotransformation system enzymes, sulfhydryl content and lipid peroxidation in a murine system

The potential of arecoline alkaloid, by direct or translactational exposure, to modify the chemopreventive efficacy of phytic acid, via modulation of hepatic biotransformation system enzymes and antioxidant defence mechanism, was assessed in a murine system. Phytic acid (500 or 1000 mg/kg b.w. per day) induced a statistically significant increase in the hepatic levels of glutathione S-transferase (GST) and sulfhydryl (-SH) in murine females and suckling neonates. The elevated levels of hepatic cytochrome b5 (Cyt. b5), cytochrome P-450 (Cyt. P-450) and the depleted level of malondialdehyde (MDA) were observed in the lactating mice. Arecoline (20 mg/kg b.w. per day) alone did not modulate the hepatic GST and -SH levels although it induced a statistically significant increase in the levels of Cyt. b5, Cyt. P-450 and MDA in the murine system. Phytic acid-modulated hepatic levels of phase II components were depressed whereas phase I enzymes and lipid peroxides were further elevated by arecoline-plus-phytic acid treatment. The implications of direct or translactational modulation in the competing potential pathways of biotransformation system enzymes in the process of chemical carcinogenesis are discussed.

Mixed disulfides from disulfiram inhibit the benzo[a]pyrene induced mutagenesis

Some mixed disulfides derived from disulfiram and endogenous thiol compounds have been synthesized, biochemically characterized and their potential antigenotoxic effects have been proposed. The present study evaluated the mutagenic and antimutagenic specificities of two mixed disulfides using S. typhimurium reversion assay, namely S-(N,N-diethyldithiocarbamoyl)-N-acetylcysteine (AC-DDTC) and-L-glutathione (GS-DDTC). The two mixed disulfides were not mutagenic to Salmonella strains TA98 and TA100 in the presence or absence of S9 mixture. The increased number of revertants by benzo[a]pyrene (B(a)P) has been reduced to the control level by the preincubation with AC-DDTC or GS-DDTC. It was not due to the killing effect of B(a)P, mixed disulfides or B(a)P-disulfide mixture. The antimutagenic effect of AC-DDTC was more potent than that of GS-DDTC. These results indicate that AC-DDTC and GS-DDTC may have a role to play in reducing the risk of mutagenic effects of B(a)P.

Chemopreventive action of oriental food-seasoning spices mixture Garam masala on DMBA-induced transplacental and translactational carcinogenesis in mice

The present study deals with the chemopreventive action of the food-seasoning spices mixture Garam masala on dimethylbenz[a]anthracene (DMBA)-induced translactational and transplacental carcinogenesis in mice. When pregnant mice were given 10 and 30 mg of Garam masala per day from Days 13-19 of gestation in addition to DMBA (5 mg/day) on Days 15-17 of gestation, the multiple-site tumor incidence declined significantly from control level of 62% to 19% and 10%, respectively, in F1 progeny. Furthermore the mean numbers of tumors per effective F1 mouse were reduced from the control value of 1.27 to 0.64 at the lower dose level (10 mg) and 0.23 at the higher dose level (30 mg) of Garam masala. Likewise, when lactating mice were given Garam masala at 10 and 30 mg/day for the first 15 days of lactation in addition to DMBA (3 mg/day) on Days 3, 6, 9, 12, and 15 of lactation, the multiple-site tumor incidence was reduced significantly from control level of 66% to 23% and 14%, respectively, in F1 progeny. The mean numbers of tumors per effective F1 mouse declined from control value of 1.43 to 0.46 at the lower dose and 0.25 at the higher dose of Garam masala. Further studies are required to analyze the nature of active chemical components and the manner in which they achieve chemoprevention in these complex model systems.

Transmammary modulation of xenobiotic metabolizing enzymes in liver of mouse pups by mace (Myristica fragrans Houtt.)

The present study examines the possible transfer of the active principle(s) of mace (aril of the plant Myristica fragrans) through the transmammary route and its ability to modulate hepatic xenobiotic metabolizing enzymes in the F1 progeny of mice. An aqueous suspension of mace at the dose levels of 0.025 or 0.1 g/animal/day was administered by oral gavage to dams from day 1 of lactation and continued daily for 14 or 21 days. Dams receiving mace treatment and their F1 pups showed significantly elevated hepatic sulfhydryl content, glutathione S-transferase and glutathione reductase activities and cytochrome b5 content. Hepatic cytochrome P450 content decreased in dams (P < 0.05) receiving the lower mace dose for 21 days and the F1 pups (P < 0.001), but increased in dams receiving the higher dose for both time periods (P < 0.001) and the lower dose for 14 days (P < 0.05). Only the 14-day-old pups of dams receiving either mace dose showed significantly elevated (P < 0.001) levels of hepatic glutathione peroxidase.

Modulation of hepatic glutathione system of enzymes in suckling mouse pups exposed translactationally to malathion

The present study examines the transmammary modulation of the glutathione system of enzymes in the F1 generation of mouse pups postnatally exposed to malathion. Lactating Swiss albino mice received either 30 or 100 mg malathion kg-1 body wt. (98% pure) for 14 or 21 days postpartum. The acid-soluble sulphydryl content was significantly increased (P < 0.001) in the liver of 14-day-old pups of dams that had received the higher malathion dose. A similar significant increase was seen in the 21-day-old male pups of dams that had received 30 mg (P < 0.05) or 100 mg (P < 0.01) malathion kg-1 body wt. Dams showed an enhanced hepatic glutathione S-transferase activity following treatment with 100 mg malathion kg-1 body wt. for 14 days (P < 0.02) and 21 days (P < 0.001). Pups of either age groups also showed enhanced hepatic glutathione S-transferase activity (P < 0.001). A significant enhancement in glutathione reductase activity was observed with malathion treatment in livers of dams and pups (P < 0.001). However, dams that had received 30 mg malathion kg-1 body wt. daily for 21 days or 100 mg malathion kg-1 body wt. for either 14 or 21 days showed significantly reduced hepatic glutathione peroxidase activity (P < 0.01, P < 0.001). A significant decrease in glutathione peroxidase activity was also observed in the liver of the 21-day-old male (P < 0.01) and female (P < 0.02) pups of dams that were treated with the higher dose of malathion.

Modulatory influence of sandalwood oil on mouse hepatic glutathione S-transferase activity and acid soluble sulphydryl level

The effect of the oil from the wood of Santalum album on glutathione S-transferase (GST) activity and acid soluble sulphydryl (SH) levels in the liver of adult male Swiss albino mice was investigated. Oral feeding by gavage to mice each day with 5 and 15 microliters sandalwood oil for 10 and 20 days exhibited an increase in GST activity in time- and dose-responsive manners. Feeding a dose of 5 microliters sandalwood oil for 10 and 20 days caused, respectively, a 1.80-fold (P < 0.001) and 1.93-fold (P < 0.001) increase in GST enzyme activity, while feeding a dose of 15 microliters of the oil per day for 10 and 20 days induced, respectively, 4.73-fold (P < 0.001) and 6.10-fold (P < 0.001) increases in the enzyme's activity. In addition, there were 1.59-fold (P < 0.001) and 1.57 (P < 0.001) increases in acid-soluble SH levels in the hepatic tissue of the mice following feeding of the oil at the dose levels of 5 and 15 microliters for 10 days. Furthermore, mice fed on a diet containing 1% 2(3)-butyl-4-hydroxyanisole (positive control) also showed an increase in hepatic GST activity and SH levels. Enhancement of GST activity and acid-soluble SH levels are suggestive of a possible chemopreventive action of sandalwood oil on carcinogenesis through a blocking mechanism.

Degree of ethoxyquin-induced nephrotoxicity in rat is dependent on age and sex

The toxicity of ethoxyquin (EQ) to rat kidney was examined in males which were either weanling or adult at the beginning of the experiment, and also in adult females. Female rats were much less susceptible to the toxic effects of EQ than males of the same age. In males damage to the cortex, mainly as an acceleration of the normal ageing process, was similar in both age groups, but rats exposed to EQ as weanlings also suffered from extensive papillary necrosis. Male rats were more prone than females to proteinuria, which was greatly exacerbated by EQ in both age groups. Thus there is very little evidence of nephrotoxicity in adult female rats on exposure to EQ at 0.5% in the diet for 26 weeks. In males, the initial age of the animal, as well as the length of treatment, influences the extent of damage.

Modulation of rat hepatic microsomal monooxygenase enzymes and cytotoxicity by diallyl sulfide

Diallyl sulfide (DAS) and other organosulfur compounds inhibit chemically induced carcinogenic and toxic responses in rodent model systems. A possible mechanism of action is the inhibition of the hepatic cytochrome P450IIE1-dependent bioactivation of the procarcinogens and protoxicants. Previous work showed competitive inhibition by DAS of N-nitrosodimethylamine (NDMA) demethylase activity in vitro, and a reduction in the microsomal level of P450IIE1 after in vivo treatment with DAS. The present studies demonstrated a time- and dose-dependent decrease of hepatic microsomal P450IIE1 activity, induction of P450IIB1 and pentoxyresorufin dealkylase activity, and moderate induction of ethoxyresorufin dealkylase activity by oral DAS treatment. DAS treatment elevated P450IIB1 mRNA but had no effect on P450IIE1 mRNA. Treatment with putative metabolites of DAS, diallyl sulfoxide and diallyl sulfone, led to similar modulations in monooxygenase activities, but the decrease of P450IIE1 activity by the sulfone occurred more rapidly. In studies in vitro, diallyl sulfone caused a metabolism-dependent inactivation of P450IIE1, but such inactivation was not observed with DAS or diallyl sulfoxide. The profile of microsomal testosterone metabolism after DAS treatment indicated an enhancement of P450IIB1-dependent 16 beta-hydroxylase activity, and a decrease in 6 beta-hydroxytestosterone production possibly related to a lower level of P450IIIA1 or IIIA2. When rats were subjected to a 48-hr fast and DAS treatment, the starvation-induced microsomal P450IIE1 level was decreased by DAS. Inhibition of hepatotoxicity due to exposure to P450IIE1 substrates, CCl4 and NDMA, by DAS was observed under a variety of treatment schedules.