In vivo effects of 3-methylcholanthrene, phenobarbital, pyrethrum and 2,4,5-T isooctylester on liver, lung and kidney microsomal mixed-function oxidase system of guinea-pig: a comparative study

The optimum conditions (pH, microsomal protein amount and substrate concentration) of guinea-pig liver, lung and kidney microsomal aniline 4-hydroxylase, ethylmorphine N-demethylase and benzo[a]pyrene hydroxylase activities were determined. Male guinea-pigs weighing 500-700 g were administered 3-methylcholanthrene (25 mg/kg, i.p. 3 days), phenobarbital (75 mg/kg, i.p. 3 days), pyrethrum (120 mg/kg, i.p. 2 days) and 2,4,5-T isooctylester (200 mg/kg, i.p. 3 days). 3-Methylcholanthrene treatment caused significant increases in liver microsomal benzo[a]pyrene hydroxylase and kidney microsomal aniline 4-hydroxylase activities. However, with phenobarbital treatment the only significant increase was observed in liver microsomal ethylmorphine N-demethylase activity. Pyrethrum treatment decreased kidney microsomal ethylmorphine N-demethylase activity significantly. 2,4,5-T isooctylester treatment increased liver microsomal aniline 4-hydroxylase and lung microsomal ethylmorphine N-demethylase activities significantly. Liver microsomal NADPH-cytochrome c reductase activity was increased significantly by phenobarbital and pyrethrum treatment. The other treatments did not cause any significant changes in microsomal NADPH-cytochrome c reductase activities of liver, lung and kidney. Cytochrome P-450 content of guinea-pig liver microsomes were increased significantly about 2.5-fold and 2-fold by treatment with 3-methylcholanthrene and phenobarbital, respectively. 3-Methylcholanthrene also caused 1 nm spectral shift in the absorption maxima of CO difference spectrum of the dithionite-reduced liver microsomal cytochrome P-450, forming P-449.     

Effect of cadmium on pulmonary and renal microsomal drug metabolizing enzymes of the guinea-pig

1. The effect of acute cadmium (Cd) treatment on pulmonary and renal microsomal aniline 4-hydroxylase and ethylmorphine N-demethylase enzyme activities of adult male guinea-pigs were assessed 72 hr following a single dose of Cd ion (2 mg Cd2+/kg i.p.). Tissue and microsomal Cd levels were also determined. 2. There were no significant differences between either lung or kidney tissue weights, microsomal protein contents or enzyme activities of Cd treated and control animals. 3. The tissues and microsomes of Cd-treated animals were found to have significantly higher levels of Cd than those of control animals. In Cd treated animals, tissue and microsomal Cd levels of kidney were found to be higher than that of lung. 4. In vitro addition of cadmium chloride (CdCl2) to incubation mixtures produced concentration related inhibitions of microsomal drug metabolizing enzymes in each tissue. However, in vitro effect of CdCl2 was found to be stronger on drug metabolizing enzymes of kidney than those of lung. In addition, while the strength of Cd effect was more pronounced on the activity of ethylmorphine N-demethylase than that of aniline 4-hydroxylase in the lung, the opposite was observed in the kidney.     

Effects of cage beddings on microsomal oxidative enzymes in rat liver

The purpose of the present studies was to evaluate the effects of some commercially available cage beddings on rat liver microsomal cytochrome P-450-dependent drug-metabolizing enzyme, ethylmorphine N-demethylase, and the carcinogen-metabolizing enzyme, benzo(a)pyrene hydroxylase. Sprague-Dawley rats were housed in cages containing cedar chip, corncob or heat-treated pinewood bedding for 3 weeks. Control rats were housed in cages on wire bottom floors containing no bedding material. Rats housed in cages containing cedar chip showed 18, 46 and 49% increases in liver cytochrome P-450 content, ethylmorphine N-demethylase and benzo(a)pyrene hydroxylase activities, respectively. The liver enzyme activities of rats housed in cages containing corncob bedding were similar to those obtained with control rats. In contrast, the pinewood-bedded rats showed a 21% decrease in ethylmorphine N-demethylase activity without affecting cytochrome P-450 content and benzo(a)pyrene hydroxylase activity. Hexobarbital-induced sleep times of the variously bedded rats were similar to those of control animals. These data suggest that the commercial bedding materials differ in their abilities to affect liver microsomal enzymes. Thus, interlaboratory variability in basal enzyme activities reported in the literature may be partly due to bedding materials used in the animal's cages.     

Characterization of sheep liver and lung microsomal ethylmorphine N-demethylase

Ethylmorphine N-demethylase activity of the sheep liver and lung microsomes was reconstituted in the presence of solubilized microsomal cytochrome P-450, NADPH-cytochrome c reductase and synthetic lipid, phosphatidylcholine dilauroyl. The Km of the lung microsomal ethylmorphine N-demethylase was calculated to be 4.84 mM ethylmorphine from its Lineweaver-Burk graph and lung enzyme was inhibited by its substrate, ethylmorphine, when its concn was 25 mM and above, reaching to 67% inhibition at 50 mM concn. The Lineweaver-Burk and Eadie-Hofstee plots of the liver enzyme were found to be curvilinear. From these graphs, two different Km values were calculated for the liver enzyme as 4.17 mM and 0.40 mM ethylmorphine. Ethylmorphine N-demethylase activities of both liver and lung microsomes were inhibited by NiCl2, CdCl2 and ZnSO4. Ethylalcohol inhibited N-demethylation of ethylmorphine in lung and liver microsomes. Acetone (5%) slightly enhanced the N-demethylase activity of the liver enzyme, whereas 5% acetone completely inhibited the lung enzyme. Phenylmethylsulfonyl fluoride at 0.10 mM and 0.25 mM concn had no effect on liver enzyme activity, while at these concns, it inhibited the activity of the lung enzyme by about 35%.     

Effects in vitro of copper and zinc on hepatic cytochrome P-450 activities

1. In previous studies we have shown that hepatic copper and zinc increases and liver microsomal cytochrome P-450 activities greatly decreases in adjuvant arthritic rats. 2. In the present paper we study if the changes in copper and zinc could be related to depression of drug microsomal activity. Thus, the effect of in vitro addition of copper or zinc to microsomal fraction upon aminopyrine N-demethylase (AND) and aniline p-hydroxylase (APH) activity was measured. 3. Both metals produced an inhibition of enzyme activity. The reduction of AND and APH activities produced by copper (ID25 = 4.7 x 10(-5)M to AND; 1.05 x 10(-5)M to APH) was greater than that obtained with zinc (ID25 = 2.26 x 10(-4)M to AND; 3.3 x 10(-4)M to APH).     

A comparative study of the effects of cadmium and nickel on liver microsomal drug metabolizing enzymes of guinea-pig in vitro

1. In vitro addition of cadmium chloride (CdCl₂) or nickel chloride (NiCl₂) to an incubation mixture produced a concentration-dependent inhibition of liver microsomal aniline 4-hydroxylase activity of male guinea-pig. The inhibitory effect of CdCl₂ on the enzyme activity was stronger than that of NiCl₂.2. While CdCl₂ also caused a concentration-dependent inhibition of liver microsomal ethylmorphine N-demethylase activity, NiCl₂ increased the enzyme activity between the concentrations 10⁻⁵ and 10⁻³ M and caused a rather abrupt decline at higher concentrations.3. When the liver 10,000 g supematants were preincubated in the presence of metals, metal-induced inhibitions increased as the time of preincubation progressed and attained their maximal rates at about 5 and 15 min for microsomal aniline 4-hydroxylase and ethylmorphine N-demethylase activities, respectively. However, no change was noted by NiCl₂ on liver microsomal ethylmorphine N-demethylase activity as the time of preincubation progressed.4. After preincubations, the concentration-dependent inhibitions produced by metals on liver microsomal drug metabolizing enzyme activities were found to be stronger and in favour of CdCl₂.     

Purification and characterization of a microsomal cytochrome P-450 with high activity of coumarin 7-hydroxylase from mouse liver

Phenobarbital-induced coumarin 7-hydroxylase is high in DBA/2J and low in C57BL/6N inbred mice; this genetic difference is encoded by the Coh locus on chromosome 7. The aim of this study was to develop an antibody specific for this cytochrome P-450 polymorphism. P-450 fractions, highly specific for phenobarbital-inducible coumarin 7-hydroxylase activity, were purified from DBA/2J and C57BL/6N mouse liver microsomes. Both proteins are 49 kDa, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Soret peaks of the reduced cytochrome . CO complexes are 451 nm. Reconstituted DBA/2J coumarin 7-hydroxylase activity exhibits a V twice as high as, and a Km value 10-fold less than, the reconstituted C57BL/6N activity. Antibodies were raised in rabbit. By Ouchterlony immunodiffusion, both antibodies show 100% cross-reactivity with DBA/2J and C57BL/6N microsomes and purified antigens. Yet, DBA/2J but not C57BL/6N 7-hydroxylase activity is inhibited by the antibody to DBA/2J P-450. Both DBA/2J and C57BL/6N activities are blocked by the antibody to C57BL/6N P-450. Neither antibody has any effect on liver microsomal d-benzphetamine N-demethylase, ethylmorphine N-demethylase, aminopyrine N-demethylase, 7-ethoxycoumarin O-deethylase, acetanilide 4-hydroxylase, or aryl hydrocarbon (benzo[a]pyrene) hydroxylase activity. The DBA/2J protein most specific for phenobarbital-induced coumarin 7-hydroxylation is designated 'P-450Coh'. Anti-(P-450Coh) precipitates a relatively minor 49-kDa protein from detergent-solubilized microsomes and from in vitro translation of poly(A+)-enriched total RNA of phenobarbital-treated DBA/2J mouse liver, whereas the major phenobarbital-induced P-450 proteins exhibit a molecular mass of about 51 kDa. The immunoprecipitated translation products correspond to a messenger RNA of 2100 +/- 100 nucleotides.     

Mixed function oxidases in kidney and duodenum of camel,guinea pig and rat

The activities of the drug-metabolizing enzymes, aniline 4-hydroxylase, benzphetamine N-demethylase and 7-ethoxycoumarin O-deethylase have been measured in vitro in kidneys and duodenum of camels (Camelus dromedarius), guinea pigs (Cavia porcellus) and rats (Rattus norvegicus). In these species, levels of hepatic microsomal parameters namely microsomal protein, cytochrome P(450), cytochrome b(5) and NADPH-cytochrome c reductase have also been determined. In general, camels seemed to have the lowest enzyme activity when compared to rats and guinea pigs. Rats showed the highest activity in NADPH-cytochrome c reductase, aniline 4-hydroxylase and ethoxycoumarin O-deethylase among these species. However, guinea pigs showed the highest enzyme activity in cytochrome P(450), cytochrome b(5) and benzphetamine N-demethylase.     

Neonatal imprinting and hepatic cytochrome P-450 II. Partial purification of a sex-dependent and neonatally imprinted form(s) of cytochrome P-450

A new form of cytochrome P-450 was partially purified from hepatic microsomes of neonatally imprinted rats (adult male and adult male castrated at four weeks of age). This new form of cytochrome P-450 appears to have an apparent molecular weight of approximately 50,000 daltons as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It appears that this form of cytochrome P-450 is either absent or present in low concentrations in cytochrome P-450 preparations isolated from neonatally nonimprinted rats (adult female and adult male castrated at birth). Reconstitution of testosterone hydroxylase and benzphetamine N-demethylase activities of this partially purified cytochrome P-450 revealed that the presence of testosterone 16α-hydroxylase activity, an imprintable microsomal enzyme, was in parallel with the imprinting status of the animals; a significantly higher activity was detected in the neonatally imprinted than that of the nonimprinted animals. This was in contrast to the nonimprintable benzphetamine N-demethylase, testosterone 7α-and 6β-hydroxylase activities which exhibited no correlation with the imprinting status of the animals. We have prepared antisera from rabbits using the partially purified cytochrome P-450 preparations from adult male rats as antigens. These antisera inhibited microsomal testosterone 16α- and 7α-hydroxylase activities in a concentration-dependent manner, without impairing 6β-hydroxylase activity. These data suggest that the partially purified cytochrome P-450 from adult male rats consists of both imprintable (16α-) and nonimprintable (7α-) testosterone hydroxylase activities. The antisera formed immunoprecipitant lines in the Ouchterlony double diffusion plates with partially purified cytochrome P-450 from both neonatally imprinted and nonimprinted adult rats. The immunoprecipitant lines, as stained by coomassie blue, suggest the homology of the cytochrome P-450 preparations from neonatally imprinted and nonimprinted rats. Immunoabsorption of the antisera against neonatally nonimprinted, partially purified cytochrome P-450 completely removed the immunoprecipitant lines without appreciably impairing the inhibitory effects of antisera on the microsomal testosterone 16α-and 7α-hydroxylase activities. In contrast, immunoabsorption of the antisera against partially purified cytochrome P-450 from adult male rats (imprinted) abolished completely both the immunoprecipitant lines and the inhibition on microsomal testosterone hydroxylation reaction (16α and 7α). The inhibitory actin of antisera on testosterone hydroxyulation was also abolished upon boiling the antisera at 100°C for 5 minutes. The biochemical and immunochemical data in this study suggest that the neonatally imprintable form or forms of hepatic microsomal cytochrome P-450 accounts for a small fraction of the bulk of total cytochrome P-450. However, the existence of this form of cytochrome P-450 is regulated by gonadal hormones during the neonatal period and accounts for the major imprintable sex difference in drug and steroid metabolism in adulthood.     

Pharmacologic effects of 4-chlorophenol in rats: comparison to clofibrate

4-Chlorophenol (4-CP) is an identified trace contaminant in commercial clofibrate preparations and the pharmacologic effects of 4-CP have not yet been widely established. We have examined the dose-dependent effects of oral 4-CP and clofibrate administration on selected hepatic parameters and on serum glucose, cholesterol, and triglyceride concentrations in male rats. 4-CP treatment (0.00125-0.08 mmol/kg, twice a day) of rats for 2 weeks increased hepatic microsomal protein (20-30%) and cytochrome P-450 (20-190%) contents without changing liver/body weight ratios. Both 4-CP (0.0025 mmol/kg body wt, twice a day) and CPIB (0.4 mmol/kg body wt, twice a day) treatment to rats for 2 weeks caused significant elevations in microsomal cytochrome P-450 content and in the maximal activities of ethylmorphine, aminopyrine, and benzphetamine N-demethylase, but not in the activity of zoxazolamine 6-hydroxylase. With the same dose of 4-CP, time-dependent increases in hepatic microsomal protein, cytochrome P-450, and the activity of benzphetamine N-demethylase were observed for a 4-week period, and the induction of hepatic microsomal benzphetamine N-demethylase activity by 4-CP was associated with an increased enzyme synthesis. 4-CP treatment produced a marked morphologic change in liver cell ultrastructure, including a proliferation of mitochondria and endoplasmic reticulum at lower 4-CP doses. A clustering of intracellular organelles (mitochondria and endoplasmic reticulum) and a foamy cytoplasm were seen at doses greater than 0.01 mmol/kg, twice a day for 2 weeks, and at 0.0025 mmol/kg, twice a day for greater than 4 weeks. The effects of 4-CP and clofibrate on fasting blood glucose and fasting serum lipid levels were also monitored throughout an 8-week period. Both 4-CP (0.005 mmol/kg body wt, twice a day) and clofibrate (0.2 mmol/kg body wt, twice a day) produced significant elevations in fasting serum glucose levels, but this dosage of 4-CP did not alter serum lipid and lipoprotein parameters, whereas clofibrate significantly reduced serum total cholesterol and high density lipoprotein cholesterol levels. These results lead us to conclude that 4-CP does not contribute to the antilipidemic effects of clofibrate.     

Synthesis, antifungal and antioxidant screening of some novel benzimidazole derivatives

Some novel benzimidazole derivatives were synthesized and their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) level, ethoxyresorufin O-deethylase (EROD) and antifungal activities were determined. A significant decrease in male rat liver microsomal LP level was noted by compounds 4c (52%), 4e (58%) and 4h (43%) at 10(-3) M concentration. Compounds 4c (100.0%), 4h (100.0%), 5c (98.0%) and 5h (100.0%) inhibited the microsomal ethoxyresorufin O-deethylase (EROD) enzyme activity better than that of the specific inhibitor caffeine (85%). Among these compounds, only compounds 4b and 4h exhibited moderate activity against C. albicans whereas the others had weak effects.     

The suppressive effect of the catatoxic steroid,pregnenolone-16α-carbonitrile,on liver microsomal cholesterol-7α-hydroxylase

The effect of the catatoxic steroid, 3β-hydroxy-20-oxo-5-pregnene-16α-carbonitrile [pregnenolone-16α-carbonitrile (PCN)] on hepatic microsomal cholesterol-7α-hydroxylase, the probable rate-limiting enzyme of bile acid biosynthesis, has been studied. Short term administration (3 days) of PCN in the diet of rats resulted in a significant decrease in the liver microsomal cholesterol-7α-hydroxylase activity, in contrast to a marked stimulation of microsomal cytochrome P-450 and ethylmorphine demethylase activity. PCN significantly depressed the cholesterol-7α-hydroxylase activity in the livers of rats with elevated levels of the enzyme produced by cholestyramine feeding. The results indicate the presence of separate control mechanisms in the regulation of bile acid synthesis and drug metabolism.     

Synthesis and evaluation of N-substituted indole-3-carboxamide derivatives as inhibitors of lipid peroxidation and superoxide anion formation

The in vitro antioxidant effects of novel N-substituted indole-3-carboxamides (I3CDs) 1-10 on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels and their free radicals scavenging properties were determined by the inhibition of superoxide anion formation (SOD). Among the synthesized compounds, 4, 5, 8 and 9 significantly inhibited SOD with an inhibition range at 84-100% at 10(-3) M concentration. The presence of halo substituents both ortho- and para- positions of these compounds resulted 100% inhibition of SOD. Comparison the activity results of halogenated and non-halogenated derivatives suggested that the halogenated compounds are more active than the non-halogenated compounds. On the other hand, the introduction of a para fluoro benzyl in the 1-position of indole (compounds 7, 8) has more impact on the SOD inhibition when the benzamide ring was mono halogenated. However, none of other compounds had a significant inhibitory effects on the level of lipid peroxidation.     

Differential haemin-mediated restoration of cytochrome P-450 N-demethylases after inactivation by allylisopropylacetamide.

Administration of allylisopropylacetamide (AIA) to phenobarbital-pretreated rats results in the destruction of several phenobarbital-inducible cytochrome P-450 isoenzymes and a correspondingly marked loss of benzphetamine N-demethylase and ethylmorphine N-demethylase activities. Accordingly, the ion-exchange h.p.l.c. or DEAE-cellulose-chromatographic profile of solubilized microsomal preparations from such rats revealed a marked decrease in the cytochrome P-450 content of several eluted fractions compared with that of microsomes from corresponding non-AIA-treated controls. Incubation of liver homogenates from such rats with haemin restores not only cytochrome P-450 content from 35 to 62% of original values, but also benzphetamine N-demethylase and ethylmorphine N-demethylase activities, from 23 to 67%, and from 12 to 36% of original values respectively. Moreover, the chromatographic profiles of microsomes prepared from such homogenates indicated increases of cytochrome P-450 content only in some fractions. Reconstitution of mixed-function oxidase activity of cytochrome P-450 by addition of NADPH: cytochrome P-450 reductase to these fractions indicated that incubation with haemin restored benzphetamine N-demethylase activity predominantly, but ethylmorphine N-demethylase activity only minimally. After injection of [14C]AIA, a significant amount of radiolabel was found covalently bound to protein in chromatographic fraction III, and this binding was unaffected by incubation with haemin. Furthermore, the extent of this binding is apparently equimolar to the amount of cytochrome P-450 refractory to haemin reconstitution in that particular fraction. Whether such refractoriness reflects structural inactivation of the apo-cytochrome remains to be determined. Nevertheless, the evidence presented very strongly argues for AIA-mediated inactivation of multiple phenobarbital-induced isoenzymes, only a few of which are structurally and functionally reparable by haemin.     

Removal of fibroblastoid cells from primary monolayer cultures of rat neonatal endocrine pancreas by sodium ethylmercurithiosalicylate

Anti-cytochrome b₅ immunoglobulin (AIg) from a rabbit was used to establish the role of cytochrome b₅ in the transfer of electrons from NADH or NADPH to the hepatic microsomal mono-oxidase system of the rat. AIg inhibited ethylmorphine (EM) N-demethylase when both NADH and NADPH were present, but had little effect when NADPH was the only source of electrons. Inhibition was reversed when AIg was preincubated with pure cytochrome b₅. Specificity of AIg was shown by its inhibitory effect on NADH cytochrome c reductase activity; it was without effect on NADPH-cytochrome P-450 reductase or aniline hydroxylase activities. It is concluded that the second electron required for EM N-demethylation can be donated by NADH via cytochrome b₅.     

Cadmium sensitivity differences between liver microsomal drug metabolizing enzyme systems of guinea-pig and rat

1. Male guinea-pigs (400-500 g) and rats (225-275 g) were given a single dose of cadmium chloride (CdCl2) (2 mg Cd2+/kg i.p.) and 72 hr later the liver microsomal drug metabolizing enzyme activities and Cd levels of tissues and microsomes were determined. 2. No significant differences were noted between Cd treated and control animal tissue weights of microsomal protein contents in either guinea-pigs or rats. 3. Cd treatment exhibited significant inhibition of the activities of aniline 4-hydroxylase and ethylmorphine N-demethylase and on the levels of cytochrome P-450 and cytochrome b5 of liver of both species but the degree of inhibition were not the same in the species; they were 23, 34, 16 and 10% in guinea-pigs and 58, 57, 25 and 13% in rats, respectively. 4. No activity changes were observed in liver NADPH-cytochrome c reductase of the species by Cd treatment. 5. The duration of hexobarbital sleeping time was significantly prolonged in both species. However, the prolongation was 1.6 fold in guinea-pigs but 3.4 fold in rats. 6. No significant differences were found between either tissue or microsomal Cd levels of guinea-pigs and rats.     

Sexual difference in properties of 5 alpha-reductase in microsome of rat submandibular glands

The properties of 5 alpha-reductase activity in the submandibular glands of rats were investigated using microsomal fraction in the presence of NADPH, and we found a sexual difference in these properties. The formation of 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 alpha, 17 beta-diol from testosterone demonstrated 5 alpha-reductase in the rat microsomal fraction of this tissue sample. Apparent michaelis constants (Km) of the 5 alpha-reductase activity for testosterone was 1.02 x 10(-6) M for the female tissue. Microsomal fraction of submandibular glands of male rats had two Kms and were determined as 1.12 x 10(-6) M and 1.01 x 10(-5) M. The lower Km of 5 alpha-reductase for male rats was similar to for the females.     

Influence of curcumin, capsaicin, and piperine on the rat liver drug-metabolizing enzyme system in vivo and in vitro

The effect of dietary supplementation of spice-active principles, curcumin (0.2%), capsaicin (0.015%), and piperine (0.02%) on the activities of the liver drug-metabolizing enzyme system was examined. All the 3 dietary spice principles significantly stimulated the activity of aryl hydroxylase. A synergistic action of dietary curcumin and capsaicin with respect to stimulating the activity of aryl hydroxylase was also evidenced when fed in combination. The activity of N-demethylase essentially remained unaffected by dietary curcumin, capsaicin, or their combination, but was significantly lowered as a result of piperine feeding. Uridine dinucleotide phosphate (UDP)-glucuronyl transferase activity was decreased by dietary piperine and the combination of curcumin and capsaicin. NADPH-cytochrome c reductase activity was significantly decreased by dietary piperine. The levels of hepatic microsomal cytochrome P450 and cytochrome b5 were not influenced by any of the dietary spice-active principles. These spice-active principles were also examined for their possible in vitro influence on the components of the hepatic drug-metabolizing enzyme system in rat liver microsomal preparation. Piperine significantly decreased the activity of liver microsomal aryl hydroxylase activity when included in the assay medium at 1 x 10(-6) mol/L, 1 x 10(-5) mol/L, and 1x 10(-4) mol/L level. Lowered activity of N-demethylase was observed in presence of capsaicin or piperine at 1 x 10(-6) mol/L in the assay medium. Hepatic microsomal glucuronyl transferase activity was significantly decreased in vitro by addition of capsaicin or piperine. Capsaicin and piperine brought about significant decrease in liver microsomal cytochrome P450 when included at 1 x 10(-6) mol/L and 1 x 10(-5) mol/L, the effect being much higher in the case of piperine. The results suggested that whereas the 3 spice principles have considerable similarity in structure, piperine is exceptional in its influence on the liver drug-metabolizing enzyme system. The study also indicated that a combination of curcumin and capsaicin does not produce any significant additive effect on the liver drug-metabolizing enzyme system.     

Differential control of adrenal drug and steroid metabolism in the guinea pig.

Studies were carried out to compare the effects of several physiological variables on adrenal microsomal drug (ethylmorphine demethylation) and steroid (21-hydroxylation) metabolism in guinea pigs. The rate of adrenal ethylmorphine (EM) metabolism increased with maturation in males but not females, resulting in a sex difference (M > F) in adrenal enzyme activity in adult guinea pigs. Twenty-one hydroxylase activity, in contrast, was similar in adrenals from males and females. The concentration of adrenal microsomal cytochrome P-450 was unaffected by age or sex. ACTH administration decreased adrenal EM demethylase activity but did not affect 21-hydroxylation. Testosterone, when given to female guinea pigs, increased the rate of EM metabolism and decreased 21-hydroxylase activity. Various compounds known to interact with adrenal microsomal cytochrome P-450 had divergent effects on EM metabolism and 21-hydroxylation $\text{in}$$\text{vitro}$. Prostaglandins E₁ and F_2α, spironolactone, and canrenone inhibited EM demethylation but not 21-hydroxylation. Simple aromatic hydrocarbons (benzene, toluene), in contrast, inhibited 21-hydroxylation but did not affect EM metabolism. The results indicate that adrenal drug and steroid metabolism are independently regulated and that different terminal oxidases (cytochrome P-450) are probably involved in adrenal 21-hydroxylation and EM demethylation.     

Effects of lysine clonixinate on cyclooxygenase I and II in rat lung and stomach preparations

Lysine clonixinate (LC) is a drug of antiinflammatory antipyretic and analgesic activity that produces minor digestive side-effects. This fact induced us to think that LC is possibly a weak COX-1 inhibitor. In order to investigate our hypothesis we inhibited cyclooxygenase activity with LC or indomethacin (INDO) in rat lung and stomach obtained from rats treated with lipopolysacharide (LPS) and control rats. Rat lung preparations incubated with 14C-arachidonic acid synthesise mainly PGE2. LC at 2.5 and 4.1 x 10(-5) M does not modify the basal production of PGE2 (probably COX-1) but at 6.8 x 10(-5) M significantly inhibited PGE2 production (approximately 48.5% inhibition, P<0.001). On the other hand, INDO at 10(-6) inhibited the basal production of PGE2 by around 73%. In LPS-treated rats, the production of PGE2 was significantly higher than in the lungs of control rats, probably due to the induction of COX-2. The addition of LC at 2.7 and 4.1 x 10(-5) M recovered the control values of PGE2 inhibiting, probably only from COX-2 activity. LC at higher concentrations (6.8 x 10(-5) M) and INDO 10(-6) M inhibited PGE2 formed by COX-2 and also partly by COX-1 activity.