Modulatory effects of Azadirachta indica leaf extract on cutaneous and hepatic biochemical status during promotion phase of DMBA/TPA-induced skin tumorigenesis in mice.

The modulation in biochemical status of skin and hepatic tissue at the time point of commencement of promotion stage of skin carcinogenesis in mice and its intervention with aqueous Azadirachta indica leaf extract (AAILE) were investigated. 7,12-Dimethylbenz(a)anthracene (DMBA, 500 nmol/100 ul of acetone) was applied topically for 2 weeks (twice weekly), followed by phorbol-12-myristate-13-acetate (TPA, 1.7 nmol/100 ul) twice weekly for 6 weeks on the depilated skin of mice and AAILE was administered orally at a dose level of 300 mg/kg body wt thrice a week for 10 weeks. DMBA/TPA treatment upregulated the phase I enzymes in skin and hepatic tissue, as revealed by the increased cytochrome P450 (CYP) and cytochrome b5 (cyt b5) levels and aryl hydrocarbon hydroxylase (AHH) activity when compared to the control group and differentially modulated the activities of phase II enzymes like glutathione-s-transferase (GST), DT-diaphorase (DTD) and uridine diphosphate glucuronosyltransferase (UDP-GT). AAILE treatment decreased the DMBA/TPA-induced increase in cutaneous CYP level and enhanced the DTD and UDP-GT activities when compared with DMBA/TPA group. In the hepatic tissue of AAILE + DMBA/TPA group, an increase in UDP-GT activity was observed when compared to DMBA/TPA group. DMBA/TPA treatment did not alter the skin lipid peroxidation (LPO) level when compared to control group, however, in the animals that received AAILE treatment along with DMBA/TPA, a significant increase in LPO was observed when compared to control group. This was associated with a decrease in cutaneous reduced glutathione (GSH) level of AAILE + DMBA/TPA group. Enhanced LPO level was observed in the hepatic tissue of DMBA/TPA and AAILE + DMBA/TPA groups when compared to control group. However, no alteration was observed in their hepatic GSH levels. The micronuclei score in hepatic tissue did not exhibit significant inter-group differences. The results of the present study suggest that apart from skin, liver may be affected during DMBA/TPA-induced skin tumorigenesis. AAILE treatment has the ability to modulate these changes potentially influencing the process of tumor formation. These findings seem to be important to carcinogenesis and its intervention with anti-cancer agents.

Optimization of tri-expression of human CYP3A4 with POR and cyt b5 in Sf 9 cells / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the optimal conditions of tri-expression of CYP3A4, POR and cyt b5 in Sf 9 cells.</p><p><b>METHODS</b>The Sf 9 cells expressing CYP3A4, POR and cyt b5 were cultured in shaker flasks. The optimized conditions, including the temperature and rotation speed, the culture volume, the amount of surfactant and the culture time were studied. The expressed products in microsomes were used to metabolize the testosterone and their metabolic activity was determined.</p><p><b>RESULTS</b>When the temperature and rotation speed of the shaker were 27 degree and 90 r/min, the cell density and culture volume were 5X105 cells/ml and 80-120 ml per 250 ml shaker flasks, respectively. When Pluronic F-68 was 0.1% and the culture time was 72 h, the condition was most suitable for culture of Sf 9 cells and expression of targeted proteins. When the ratio of the volume of three added viruses was 1:1:1, the expression condition was optimal, under which the Km, Vmax, and CLint for testosterone metabolism were 119.6 μmol/L,0.52 μmol/(min*g protein) and 4.34 ml/(min*g protein), respectively.</p><p><b>CONCLUSION</b>The conditions of tri-expressing of CYP3A4, POR and cyt b5 have been optimized in the study and the product CYP3A4 is obtained with higher metabolic activity.</p>

Antidote for acquired methemoglobinemia: methylene blue

Methylene blue (MB) is an effective antidote for methemoglobinemia. MB is a basic dye, yielding a blue solution. In the human body, hemoglobin is the oxygen-carrying protein including a ferrous atom. Hemoglobin is oxidized to methemoglobin (MetHb) with the ferric atom, which cannot bind to or carry oxygen. Equilibrium between hemoglobin and MetHb is approximately 99:1. Thus a healthy man can have about 1% of methemoglobinemia. The cytochrome b5 MetHb reductase pathway plays a major role in reducing MetHb to hemoglobin. The nicotin amide adenine dinucleotide phosphate (NADPH) MetHb reductase pathway is a minor reducing system of MetHb, and it needs NADPH as a cofactor. However, to the exceeding exogenous oxidative stress, the cytochrome b5 MetHb reductase pathway is soon exhausted, and the NADPH MetHb reductase pathway can be activated 4 to 5 times by the exogenous cofactor, MB. The decision to initiate MB therapy for methemoglobinemia depends on the MetHb level and the symptoms. The indication for MB therapy in a symptomatic patient is a MetHb level >20% and in an asymptomatic patient, a MetHb level >30%. Patients with comorbidities such as anemia, heart disease, pneumonia, chronic obstructive pulmonary disease, or liver cirrhosis can be candidates for MB therapy with an even lower MetHb level. The recommended initial dose of MB is 1 to 2 mg/kg. It can be repeated every 30 minutes to 1 hour. However, the dose should not exceed 7 mg/kg. A high dose of MB may induce methemoglobinemia paradoxically and also cause hemolytic anemia. Like other antidotes, MB has its own adverse effects.

Effects of salvianolic A on rat liver microsomal cytochrome P450 system / 中国中药杂志

<p><b>OBJECTIVE</b>To study the effects of salvianolic acid A on content of cytochrome P450,cytochrome b5 and CYP1A2, CYP2E1 activities of rats.</p><p><b>METHOD</b>The rats were randomly divided into two groups and each group contained 5 male rats and 5 female rats. One is control group, another is dosage group. The dosage group was injected salvianolic acid A into a rat tail vein at doses of 20 mg x kg(-1) x d(-1) for 5 days. The control group was injected placebo into a rat tail vein at the same doses as the dosage group. The content of cytochrome P450 and cytochrome b5 of rats were assayed using UV and CYP1A2, CYP2E1 activities were evaluated using probe substrate.</p><p><b>RESULT</b>After salvianolic acid A was injected into rats tail vein for 5 days, the total content of cytochrome P450 and cytochrome b5 and CYP1A2 and CYP2E1 activities have no statistical significance of differences than the control group.</p><p><b>CONCLUSION</b>Salvianolic acid A has no effects on CYP1A2 and CYP2E1 activities, indicating that there is no internation between salvianolic acid A and the drugs metabolized by CYP1A2 or CYP2E1.</p>

Effect of volatile oil from nutmeg on liver microsomal cytochrome P450 in mice / 中国中药杂志

<p><b>OBJECTIVE</b>To study the effect of the volatile oil from nutmeg on liver microsomal cytochrome P450 in mice.</p><p><b>METHOD</b>Mice were administered the volatile oil from nutmeg at 0.4, 0.8 and 1.2 mg x g(-1), respectively, twice a day for 10 days. And then, the contents of liver microsomal cytochrome P450 (CYP), cytochrome b5 (Cytb5), MDA and GST in serum were examined by UV chromatography method.</p><p><b>RESULT</b>The contents of liver CYP, Cytb5 and GST in serum were increased significantly (P < 0.01) and the contents of MDA was reduced significantly (P < 0.01).</p><p><b>CONCLUSION</b>The volatile oil from nutmeg showed induction effect on the hepatic microsomal CYP in mice.</p>

Potent protective effect of alpha -tocopherol and fish oil on in vivo paraquat induced oxidative damage in rats

The potential protective role of alpha-tocopherol and fish oil against oxidative damage induced by paraquat were investigated. Forty male albino rats with average body weight of 100-120 gm were housed in 8 groups of 5 rats each. The first group served as control and injected with saline, group 2 was injected with a single dose of paraquat [10 mg/kg, intraperittoneally] for 24 h prior to decapitation [P], group 3 was administered orally with vitamin E [100 mg/kg] five times a week [E]. group 4 was administered orally with fish oil [20 mg/kg] five times a week [FO]; group 5 received FO+E, groups 6, 7 and 8 were administrated with P+E, P+FO and P+E+FO respectively. The content of microsomal proteins, drug metabolizing enzymes and thiobarbituric acid reactive substances [TEARS] were determined in liver microsome after treatment. Vitamin E together with fish oil significantly decreased the content of cytochrome b[5] [p<0.01], c ytochrome P-450 [p<0.001]. glutathione-S-transeferase [p<0.001] and cytochrome C-reductase [p<0.001] when given before paraquat injection. Meanwhile, this combination of vitamin E and fish oil significantly [p<0.05] increased amidopyrine N-demethylase. On the other hand vitamin E and fish oil alleviated the paraquat induced increase in TBARS. In conclusion, oral administration of vitamin E and fish oil are effective in reducing the activity of selected drug metabolizing enzymes and are also effective in reducing lipid peroxidation process caused by paraquat. So, these combinations provide a potent protection against paraquat-induced oxidative toxicity in rats' liver

Impediment of diethylnitrosamine induced hepatotoxicity in male Balb/c mice by pretreatment with aqueous Azadirachta indica leaf extract.

Considering the hepatoprotective properties of Azadirachta indica, the present study was designed to evaluate its preventive effects against diethylnitrosamine (NDEA) induced hepatotoxicity in male Balb/c mice. Exposure of NDEA caused a significant increase in micronucleated cell score, lipid peroxidation levels (LPO) and activity of lactate dehydrogenase (LDH). A significant decrease in reduced glutathione (GSH) contents and activity of glutathione-S-transferase (GST) was also observed upon NDEA treatment, whereas their activities of cytochrome P450 and cytochrome b5 showed non-significant alterations. Aqueous A. indica leaf extract (AAILE) pretreatment showed protective effects against NDEA induced toxicity by decreasing the frequency of micronucleated cell, levels of LPO and LDH activity. Also, a decreased activity of GST, cytochrome P450 and an increased activity of cytochrome b5, GSH contents was observed when AAILE pretreated mice were injected with NDEA. Only AAILE treatment caused a noticeable decrease in the frequency of micronuclei, activity of cytochrome P450 and cytochrome b5, but a significant increase in the activity of GST and GSH contents, whereas, non significant alterations were observed in the activity of LDH and levels of LPO. Significance of these observations with respect to hepatoprotective efficacy of A. indica has been discussed in the present manuscript.

Modulation of the activities and mRNA expression of cytochrome P450 isoenzymes in rat liver by Panax gingseng and coadministration with Veratrum nigrum / 中国中药杂志

<p><b>OBJECTIVE</b>To study the modulatory effect of Panax gingseng and coadministration with Veratrum nigrum on the activity and mRNA expression of cytochrome P450 isoenzymes in rat liver.</p><p><b>METHOD</b>Rat liver microsomal cytochrome P450, b5, aminopyrine N-demethylase(APND), p-nitrophenol-hydroxylase(pNPH)activities were quantitated by UV chromatography. The mRNA expression level of five CYP isoenzymes CYP1A1, CYP2B1/2, CYP2C11, CYP2E1 and CYP3A1 were detected by semi-quantitative reverse transcriptase-polymerase chain reaction(RT-PCR).</p><p><b>RESULT</b>P. gingseng coadministrated with V. nigrum obviously decreased the P450 contents of liver microsomes, and the b5 contents. Both single and combined used inhibited the activities of aminopyrine N-demethylase. At the mRNA level, the expression of CYP2C11 markedly induced exposure to V. nigrum, but combinative groups decreased the expression of CYP2C11. The combination of P. gingseng and V. nigrum induced the expression of CYP1A1. P. gingseng has inhibitory effect on CYP2B1/2 and inductive effect used with V. nigrum. The combination of P. gingseng with V. nigrum also induced the expression of CYP3A1.</p><p><b>CONCLUSION</b>P. gingseng used singly has some different modulation effects compared with combinative used, which may occur because of drug-drug interaction based on cytochrome P450. To elucidate the drug-drug interaction, it needs further analysis and metabolism research.</p>

Chemomodulatory effect of Moringa oleifera, Lam, on hepatic carcinogen metabolising enzymes, antioxidant parameters and skin papillomagenesis in mice.

The modulatory effects of a hydro-alcoholic extract of drumsticks of Moringa oliefera Lam at doses of 125 mg/kg bodyweight and 250 mg/ kg body weight for 7 and 14 days, respectively, were investigated with reference to drug metabolising Phase I (Cytochrome b(5) and Cytochrome p(450) ) and Phase II (Glutathione-S- transferase) enzymes, anti-oxidant enzymes, glutathione content and lipid peroxidation in the liver of 6-8 week old female Swiss albino mice. Further, the chemopreventive efficacy of the extract was evaluated in a two stage model of 7,12 - dimethylbenz(a)anthracene induced skin papillomagenesis. Significant increase (p<0.05 to p<0.01) in the activities of hepatic cytochrome b(5), cytochrome p(450), catalase, glutathione peroxidase ( GPx ), glutathione reductase (GR), acid soluble sulfhydryl content (-SH ) and a significant decrease ( p<0.01 ) in the hepatic MDA level were observed at both dose levels of treatment when compared with the control values. Glutathione-S- transferase ( GST )activity was found to be significantly increased (p<0.01 ) only at the higher dose level. Butylated hydroxyanisol (BHA ) fed at a dose of 0.75% in the diet for 7 and 14 days (positive control ) caused a significant increase (p<0.05 to p<0.01) in the levels of hepatic phase I and phase II enzymes, anti- oxidant enzymes, glutathione content and a decrease in lipid peroxidation. The skin papillomagenesis studies demonstrated a significant decrease (p<0.05 ) in the percentage of mice with papillomas, average number of papillomas per mouse and papillomas per papilloma bearing mouse when the animals received a topical application of the extract at a dose of 5mg/ kg body weight in the peri-initiation phase 7 days before and 7 days after DMBA application, Group II ), promotional phase (from the day of croton oil application and continued till the end of the experiment, Group III ) and both peri and post initiation stages (from 7 days prior to DMBA application and continued till the end of the experiment, Group IV) compared to the control group (Group I ). The percentage inhibition of tumor multiplicity has been recorded to be 27, 72, and 81 in Groups II, III, and IV, respectively. These findings are suggestive of a possible chemopreventive potential of Moringa oliefera drumstick extract against chemical carcinogenesis.

Bladder microsomal enzymes in health and disease

The bioactivation of N-nitrosamines and polycyclic aromatic hydrocarbons [PAHs] is mediated primarily by the mixed-function oxidase system, which includes dimethylnitrosamine N-demethylase I, arylhydrocarbon hydroxylase, cytochrome P-450, cytochrome b[5], and ethoxycoumarin deethylase. Most of carcinogens and xenobiotics are conjugated and detoxified by phase II drug-metabolizing enzymes such as glutathione S-transferase. The present study showed the influence of Schistosoma haematobium on the activity of the above-mentioned enzymes in thirteen schistosome-infected human bladder tissues compared with those of fifteen schistosome-free samples. The contents of cytochrome P-450 and cytochrome b[5] increased in the bladder 157 tissues by 48% and 69% respectively. Moreover, the activities of dimethylnitrosamine N-demethylase I and arylhydrocarbon hydroxylase, ethoxycoumarin O-deethylase, ethoxyresorufin O-deethylase, and pentoxyresorufin O-depentylase increased by 75%, 159%, 49%, 63% and 44% respectively. The signal intensity for cytochrome P-450 2E1 was greatly increased over the control. The present study clearly demonstrated that S. haematobium changes the activity of carcinogen-metabolizing enzymes. We conclude that S. haematobium could enhance the carcinogenicity of polycyclic aromatic hydrocarbons [e.g. benzo[a]pyrene] and N-nitrosamines in the human bladder tissues, and probably other tissues, since there is an association between schistosomiasis and bladder cancer

Effect of country liquor (Indian alcoholic beverage) on carcinogen activating and detoxifying enzymes.

The levels of some important drug activating and detoxyfying enzymes were estimated in the livers of Swiss mice treated with a local brand of country liquor. Following liquor ingestion in male mice elevated levels of hepatic cytochrome P-450 were observed, while female mice did not show this. Cytochrome b5 levels remained unchanged. Similarly in male mice, increase in hepatic reduced glutathione levels were obtained while in female mice, decrease in this was observed. The activity of glutathione S-transferase was not changed. It is suggested that the increases in cytochrome P-450 and in hepatic reduced glutathione may be important determinants in carcinogenecity of the country liquors.

Evaluation of the modulatory influence of food additive-garam masala on hepatic detoxication system.

Potential chemopreventive role of an Indian food additive-garam masala has been assessed through its impact on the hepatic levels of detoxication enzymes like glutathione S-transferase (GST), cytochrome b5 (cyt. b5) and cytochrome P-450 (cyt. P-450), and acid soluble sulfhydryl (-SH) content in 8-9 weeks old Swiss albino mice of either sex fed on the 0.5%, 1.0% and 1.5% (w/w) garam masala in the diet for 10 days. The data from this short term study revealed the significant but dose-independent alteration in the levels of detoxication system enzymes. The results suggest the possible chemopreventive potency of this widely used food additive by being a bifunctional inducer of detoxication system.

Effect of metronidazole on the hepatic mixed function oxygenases (cytochromes b5 and P-450) in Swiss mice.

Effect of metronidazole (MNZ) treatment (oral and ip) on activities of cytochrome b5 and P-450 was studied in male, virgin and pregnant female mice. Activities of both the cytochromes increased in virgin mice treated with 2 mg (ip or PO, per mouse) but not in male and pregnant females. 30 mg dose (per mouse) was toxic in pregnant mice but increased the cytochromes activities in males and virgin females. HPLC analysis of liver MNZ levels showed that virgin females had higher MNZ content than male and pregnant females when treated with ip injection of MNZ (250 mg/kg).