The Lathyrus sativus neurotoxin: evidence of selective retention in monkey tissue

Epidemiological studies implicate the food toxin, l-3-oxalylamino-2-aminopropionic acid (OAP), in outbreaks of neurolathyrism. The disease occurs only in humans who have eaten excessive amounts of OAP-containing legumes for many months, thus suggesting that chronic exposure to OAP is needed to cause nerve damage and paralysis. These experiments were carried out to determine whether OAP might be selectively retained by certain tissues. With repeated exposure to OAP, tissues which selectively retain the toxin might build up sufficient concentrations to produce nerve damage. To investigate the rate of loss of OAP from animal tissue, we injected young squirrel monkeys with l-3-[¹⁴C]oxalylamino-2-aminopropionic acid and analyzed tissue for radioactivity 1, 24, and 72 hr later. Cerebellum was conspicuously different from other parts of brain in that the concentration of radioactivity (dpm/g) relative to brain as a whole increased with time. At 1 hr, the concentration in cerebellum was about the same as in brain as a whole; at 72 hr, it was more than twice as great. The half-life for disappearance of radioactivity from cerebellum (32.7 hr) matched that for bone and was the longest observed in these experiments. Unchanged [¹⁴C]OAP was the major component of radioactivity recovered from brain and other tissues. Entrapped blood in brain was negligible. These experiments suggest that cerebellum may selectively retain OAP and thus tend to accumulate neurotoxic concentrations. Cerebellum contains glutamate receptors, and OAP is a known glutamate antagonist.     

The nutritive value of grasspea (Lathyrus sativus) and allied species, their toxicity to animals and the role of malnutrition in neurolathyrism

The safe use of grasspea (Lathyrus sativus) and allied species (L. cicera, L. clymenum and L. ochrus) requires a better understanding of the factors that are involved in the development of neurolathyrism. A suitable animal model is needed. The nutritional quality, seed chemical composition, the role of malnutrition, synergistic action of antinutritional factors, the toxicity of both seed and forage to animals, metabolism and tissue distribution of the toxic amino acid beta-N-oxalyl-alpha,beta-l-diaminopropionic acid (ODAP) in mammals are reviewed. Malnutrition is not necessary for the development of neurolathyrism, however, the supply of sulfur amino acids by Lathyrus spp. is limited by the combined action of several antinutritional factors and the low inherent levels in the seeds. Metabolism or excretion of ODAP and clearance from the central nervous system appear to function well under normal circumstances, while species differences exist. Interruptions to these processes and excessive concurrent demands for reduced sulfur amino acids are likely to be conducive to the onset of neurotoxicity.     

Raphanus sativus extract protects against Zearalenone induced reproductive toxicity, oxidative stress and mutagenic alterations in male Balb/c mice

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by several species of Fusarium in cereals and agricultural products. It has been implicated in several mycotoxicosis in farm animals and in humans. There is unequivocal evidence of reproductive toxicity of ZEN in male mice although the mechanism of action is unknown. Several reports suggest that exposure to ZEN resulted in oxidative stress, genotoxicity and perturbation of reproductive parameters. Therefore, the aim of the current study was to evaluate the protective effects of aqueous extract of Raphanus sativus growing in Tunisia against ZEN-induced reproductive toxicity and oxidative stress. Fifty male Balb/c mice were divided into five groups and treated for 28 days as follows: the control group, olive oil-treated groups, another treated with ZEN (40 mg/kg b.w), the last one treated with R. sativus extract alone (15 mg/kg b.w) and the other with ZEN + R. sativus extract. Testis samples were collected for the epididymal sperm count, testosterone concentration, and MDA level, GPx, CAT and SOD activities. Blood samples were collected for different biochemical analyses. Also, RAPD-PCR method was performed to assess the antigenotoxic effect of the extract in germ cells. The results indicated that ZEN-induced toxicological effects in accordance to those reported in the literature: decreasing in the sperm number, testosterone level and antioxidant enzyme status. The RAPD-PCR analysis revealed an alteration in the DNA bands patterns between control and ZEN-treated mice. The extract alone, rich in many antioxidant compounds, was safe and succeeded in counteracting the oxidative stress and protect against the toxicity resulting from ZEN.     

Protective effect of leaves of Raphinus sativus Linn on experimentally induced gastric ulcers in rats

Raphinus sativus Linn (Cruciferae) commonly known as ‘Radish’ is a multipurpose herb cultivated in different parts of the world for its edible roots and leaves. The present study was aimed to evaluate the antiulcer activity of leaf extracts of R. sativus Linn on acetic acid induced chronic gastric ulcer and pylorus ligation induced gastric ulcer in rats. The acute oral toxicity study revealed that all the extracts were safe up to 2000 mg/kg per oral dose; hence one-tenth of this dose was selected for evaluation of antiulcer activity. In acetic acid induced gastric ulcer models, the ERS, CRS, EARS and AQRS have offered significant protection against acetic acid induced ulcers when compared to control group. While in pylorus ligation induced ulcer model the ERS, EARS and AQRS showed significant protection by decreasing the ulcer index, total acidity and free acidity. In conclusion the leaf extracts of R. sativus Linn are found to possess antiulcer property in the experimental animal models of gastric ulcers, which is consistent with the literature report in the folk medicine.     

Microsomal electron transport and xenobiotic monooxygenase activities during the embryonic period of development in the killifish,Fundulus heteroclitus

The developmental patterns of aryl hydrocarbon hydroxylase (AHH) activity and NADPH-cytochrome c reductase activity were followed during embryonic development in Fundulus. AHH activity was localized in microsomal fractions prepared from whole Fundulus embryos and eleutheroembryos. On the basis of this subcellular localization, the requirements of O₂ and NADPH for activity, and sensitivity to carbon monoxide and cytochrome c inhibition, the AHH activity in Fundulus embryos and eleutheroembryos appeared to be cytochrome P-450 dependent. AHH activity was measurable in stages prior to the appearance of the liver rudiment, and during subsequent embryonic development the extrahepatic tissues were likely to have contributed substantially to the AHH activity measured. At all stages assayed before hatching, microsomal AHH specific activity remained uniformly low, but within 24 hr of hatching, AHH specific activity increased about ninefold. This posthatching increase in AHH activity was not age dependent, nor developmental stage dependent, but rather required hatching, and was not due to the presence of endogenous inhibitors in prehatching stages. The levels of NADPH-cytochrome c reductase activity and AHH activity were not closely correlated in whole embryo and eleutheroembryo microsomes, but the AHH activity in these preparations apparently was not limited by the levels of the NADPH-cytochrome c (P-450) reductase. The presence of AHH activity in Fundulus embryos during the period of active organogenesis, prior to hatching, indicates that this species is likely to be susceptible to a variety of teratogens requiring metabolic activation, and this may be the case for other species of fish as well.     

Factors affecting β-ODAP content in Lathyrus sativus and their possible physiological mechanisms

A neuroexcitatory non-protein amino acid, β-N-oxalyl-l-α,β-diaminopropionic acid (β-ODAP), present in the seeds of the hardy legume crop grass pea (Lathyrus sativus L.), was considered responsible for human lathyrism. The levels of β-ODAP were reported to vary in different tissues during plant development, and to be affected by a wide range of environmental stresses. In this paper, dynamic changes in β-ODAP level at specific stages of plant development as well as the influences of various environmental factors, including nutrient deficiency, drought, salinity, toxic heavy metals, and Rhizobium symbiosis on β-ODAP levels were analyzed, highlighting the relationship between changes in β-ODAP concentrations and Rhizobium growth. Possible mechanisms underlying β-ODAP accumulation are proposed and future research is suggested.     

N-oxidation of N,N-dimethylaniline in the rabbit and rat lung

We have reported previously that chlorpromazine (CPZ) and imipramine (IMP) are metabolized via N-oxidation by the rat lung, while they are not appreciably metabolized by the rabbit lung. Indeed, marked species differences exist in the pulmonary N-oxidation of these pneumophilic drugs. In the present studies, the isolated, ventilated and perfused lung (IPL) preparations as well as in vitro preparations of the rabbit and rat lungs were used to examine the pulmonary disposition of [¹⁴C]-N,N-dimethylaniline (DMA) which has been used frequently as a substrate for N-oxidation. Although the IPLs of both species were active in DMA N-oxidation, the rabbit lung was more active in DMA N-oxidation than the rat lung on the basis of per g lung. The gradual decline in radiolabel concentration in the perfusate was more marked in the rat than in the rabbit IPL. This decline was not due to the drug accumulation in the lung, but to its volatility. There was no dose dependency in the tissue/medium DMA concentration ratios (approximately 1.60), indicating uptake by simple diffusion and low affinity for the lung tissue. In vitro lung preparations showed higher DMA N-oxidase activity in the rabbit than in the rat, regardless of whether whole homogenate, post-mitochondrial supernatant fraction or microsomal fraction was used, or how the activities were expressed (per mg protein or per g tissue). These results suggest that, although DMA is not highly concentrated in the lung, it is N-oxidized by the lung and that DMA N-oxidase is different from CPZ or IMP N-oxidase reported previously.     

Evidence that deprenyl,a type B monoamine oxidase inhibitor,is an indirectly acting sympathomimetic amine

Various doses of l-deprenyl were tested for their abilities to increase blood pressure or heart rate in animals pretreated with a ganglionic blocking agent. The use of a ganglionic blocker (chlorisondamine) ensured that deprenyl-induced responses were mediated by the peripheral autonomic nervous system, and that these responses were not influenced by the central nervous system. It was found that l-deprenyl had a modest ability to increase blood pressure and a marked ability to increase heart rate. The ability of l-deprenyl to increase heart rate was diminished or abolished by propranolol, reserpine, and chemical sympathectomy (6-hydroxydopamine). Deprenyl-induced responses were negligibly affected by adrenalectomy. These data suggest that l-deprenyl is an indirectly acting sympathomimetic amine whose responses are mediated by norepinephrine in postganglionic sympathetic neurons. An additional finding was that desmethylimipramine, a known blocker of the norepinephrine pump, antagonized the effects of l-deprenyl. This finding suggests that l-deprenyl enters sympathetic neurons via the membrane pump. The ability of l-deprenyl to enter sympathetic neurons and evoke release of endogenous amines was not accompanied by a significant loss of tissue (heart) norepinephrine.     

Stress-related over-enhancement of the hypothalamic-pituitary-adrenal axis causes experimental neurolathyrism in rats

Neurolathyrism is a motor neuron disease that is caused by the overconsumption of grass peas (Lathyrus sativus L.) under stressful conditions. The neuro-excitatory β-N-oxalyl-L-α,β-diaminopropionic acid present in grass peas was proposed the causative agent of spastic paraparesis of the legs. Historical reports of neurolathyrism epidemics, studies of neurolathyrism animal models, and in vitro studies on the mechanism of β-N-oxalyl-L-α,β-diaminopropionic acid toxicity support the hypothesis that stress increases susceptibility to neurolathyrism. To elucidate the role of stress in neurolathyrism-induced motor dysfunction, we focused on the hypothalamic-pituitary-adrenal axis in a rodent model of neurolathyrism. Our results implicated increased glucocorticoid and neuroinflammation in the motor dysfunction (paraparesis) exhibited by the stress loaded rat models of neurolathyrism.     

Hepatic drug transport in the rat: A comparison between isolated hepatocytes,the isolated perfused liver and the liver in vivo

The hepatic transport of three different drugs, the organic anion dibromosulphophthalein, the organic cation d-tubocurarine and the uncharged compound ouabain was studied in vivo in the isolated perfused rat liver and isolated hepatocytes. The respective clearances by uptake were determined for the various substrates and corrected for differences in hepatic blood flow and extracellular protein binding in the three liver preparations. The corrected uptake values in the intact organ, in vivo and in the isolated perfused liver were highly comparable; for dibromosulphophthalein a clearance of 2.1ml/minper 10⁶ hepatocytes was found in vivo, whereas in perfusion a value of 2.4 ml/min per 10⁶ cells was calculated. For d-tubocurarine, the values were 34 × 10^?4 and 55 × 10^?4ml/min per 10⁶ cells obtained in vivo and in the isolated perfused organ, respectively. With ouabain as the substrate, the in vivo clearance amounted to 5.1 × 10^?2, whereas in the isolated perfused liver a value of 4.8 × 10^?2ml/min per 10⁶ cells was calculated. The clearance by uptake obtained for dibromosulphophthalein and ouabain in the isolated hepatocytes appeared to be a factor of 2–3 lower than in the intact organ. In the case of d-tubocurarine however the clearance was identical to that in vivo and the isolated perfused liver.The rate of secretion from isolated hepatocytes was, for dibromosulphophthalein identical to, and for d-tubocurarine and ouabain lower than that in the intact organ, especially as compared with the in vivo preparation.It is concluded that transport function is well preserved in the isolated perfused liver and isolated hepatocytes. For certain substrates freshly isolated hepatocytes may exhibit a somewhat lower uptake and/or secretion rate, in spite of a good cell quality as judged by generally accepted criteria for cell viability. Whether this is due to changes in membrane composition (not detected by our viability tests) or a selection of a subpopulation of hepatocytes, is discussed.     

Synthesis of deuterium- and tritium-labeled 4-hydroxyandrostene-3,17-dione,an aromatase inhibitor,and its metabolism in vitro and in vivo in the rat

The metabolism of the aromatase inhibitor 4-hydroxyandrostenedione (4-OHA) was studied in vitro and in vivo in the rat. To accomplish this, deuterium- and tritium-labeled 4-OHA were prepared from 4-hydroxyandrosta-4,6-diene-3,17-dione. The latter was synthesized from 4-androstene-3,17-dione. Using deuterated 4-OHA in in vitro incubations of rat ovarian microsomes, 4-hydroxytesterone (4-OHT) was identified by gas chromatography/mass spectroscopy as the major metabolite. 4-OHT constituted approximately 20% of the total radioactivity from [6,7-³H]-4-OHA in the ovarian microsomal incubations. Conversion of [6,7-³H]-4-OHA to 4-hydroxyestrone was approximately 0.1%. The major metabolite of [6,7-³H]-4-OHA in vivo identified in the free, neutral fraction of rat blood was 3β-hydroxyandrostane-4,17-dione. This metabolite accounted for approximately 5% of the total radioactivity in the blood, whereas 4-OHT accounted for only 0.1%. 4-OHT inhibited in vitro ovarian aromatization by 59%, but 3β-hydroxyandrostane-4,17-dione had little effect. It was concluded that the in vivo effects of 4-OHA previously reported are largely due to its own activity although additional effects of its metabolic products cannot be excluded.     

Herbal medicine for depression, anxiety and insomnia: A review of psychopharmacology and clinical evidence

Research in the area of herbal psychopharmacology has increased markedly over the past decades. To date however, a comprehensive review of herbal antidepressant, anxiolytic and hypnotic psychopharmacology and applications in depression, anxiety and insomnia has been absent. A search of MEDLINE (PubMed), CINAHL, PsycINFO, and the Cochrane Library databases was conducted (up to February 21st 2011) on commonly used psychotropic herbal medicines. A review of the literature was conducted to ascertain mechanisms of action of these botanicals, in addition to a systematic review of controlled clinical trials for treatment of mood, anxiety and sleep disorders, which are common comorbid psychiatric disorders. Specific emphasis was given to emerging phytomedicines. Analysis of evidence levels was conducted, as were effect sizes (Cohen's d) where data were available. Results provided evidence of a range of neurochemical, endocrinological, and epigenetic effects for 21 individual phytomedicines, which are detailed in this paper. Sixty six controlled studies were located involving eleven phytomedicines. Several of these provide a high level of evidence, such as Hypericum perforatum for major depression, and Piper methysticum for anxiety disorders. Several human clinical trials provide preliminary positive evidence of antidepressant effects (Echium amoenum, Crocus sativus, and Rhodiola rosea) and anxiolytic activity (Matricaria recutita, Ginkgo biloba, Passiflora incanata, E. amoenum, and Scutellaria lateriflora). Caution should however be taken when interpreting the results as many studies have not been replicated. Several herbal medicines with in vitro and in vivo evidence are currently unexplored in human studies, and along with use of emerging genetic technologies “herbomics”, are areas of potential future research.     

Induction of phencyclidine metabolism by phencyclidine,ketamine, ethanol,phenobarbital and isosafrole

The in vitro metabolism of phencyclidine (PCP) was investigated in 9000 g supernatant fractions of both control and PCP-, ketamine-, ethanol-, phenobarbital- or isosafrole-pretreated rats. Levels of PCP, trans-4-phenyl-4-piperidinocyclohexanol (I), 1-(1-phenylcyclohexyl)-4-hydroxypiperidine (II), N-(5-hydroxypentyl)-1-phenylcyclohexylamine (IX), and 5-(1-phenylcyclohexylamino)-valeric acid (X) were monitored by gas Chromatographic analysis in all cases. The inhibition of metabolism by N₂, CO, SKF-525A or 2,4-dichloro-6-phenylphenoxyethylamine (DPEA), or deletion of NADPH or protein, implied the involvement of cytochrome P-450 in the reactions. The various inducing agents affected the metabolism of PCP in different ways, implying that at least several isozymes of cytochrome P-450 were involved in the total metabolism. The majority of the consumed PCP was not accounted for by the measured metabolites so that some other metabolic pathways of major quantitative importance must be operative.     

beta-adrenergic receptors of human leukocytes: studies with intact mononuclear and polymorphonuclear cells and membranes comparing two radioligands in the presence and absence of chloroquine

Owing to the large differences in reported values for β-adrenergic receptor numbers and binding affinity in normal leukocytes, we undertook a systematic re-examination of the binding of two widely used beta antagonists, (-)-[³H]dihydroalprenolol (DHA) and $\text{(±)-}\text{[}{}^{125}\text{I]iodohydroxybenzylpindolol}$ (HYP), to intact normal mononuclear (MN) leukocytes and polymorphonuclear (PMN) leukocytes and membrane preparations. Assays were conducted in the presence and absence of chloroquine, which has been proposed recently to eliminate ligand uptake into a non-receptor cell compartment such as lysosomes. The binding curves relating radioligand concentration to specific sitesper intact cell were biphasic. At high (10–24 nM) (-)-DHA ligand concentration in the absence of chloroquine, a large number (20,000–60,000 sites/cell) of low affinity (K_d 12–15 nM) stereospecific binding sites were detected in both cell types. This class of binding sites was eliminated by 10 ,μM chloroquine not only in PMN cells but also in the lysome-poor MN cells (? 90% lymphocytes), leaving 2000–3000 specific high affinity (-)-DHA sites/cell. In the absence of chloroquine, comparably low numbers of specific high affinity binding sites/cell were also obtained by the use of appropriately low concentrations of (-)-DHA or (±)-HYP (800 pM or less). However, even at these low radioligand concentrations chosen to measure high affinity specific binding, the addition of 10 μM chloroquine produced a moderate reduction in the number of sites/cell, without a detectable change in the apparent K_d. Mean (± S.E.M.) site numbers obtained in the presence of chloroquine were: 1331 ± 100 sites/MN cell and 1135 ±129 sites/PMN cell (K_d 143–153 pM) using (-)-DHA; and 1487 ± 210 sites/MN cell and 1065 ± 69 sites/PMN cell [avg. K_d(±) 224–274 pM] using (±)-HYP. Chloroquine had no effect on agonist-stimulated cAMP production but produced an apparent increase in the effectiveness of (-)-propranolol as an inhibitor of DHA binding. Competition studies on the binding of DHA and HYP with zinterol and practolol confirmed that the receptor was of the β₂-subtype for both MN and PMN cells. The detection of a moderately larger number of high affinity binding sites at saturation (Scatchard analysis) by (±)-HYP than by (-)-DHA was a consistent finding with either intact cells or membranes, with or without chloroquine. The possible overestimation of receptor numbers by a racemic ligand such as (±)-HYP is discussed and leads us to favor the use of a pure stereoisomer such as (-)-DHA. A system employing 800 pM (-)-[³H]DHA, 1 ,μM (-)-propranolol and 10, μM chloroquine with intact MN and PMN cells yielded reproducible and plausible results. Our values for β-adrenergic receptor numbers of intact MN and PMN cells and membranes are compared to others in the literature.     

Studies on the embryotoxic effects of ortho-, meta- and para-xylene

CFY rats were exposed to inhalation of ortho-, meta-, or para-xylene at 150, 1500, or 3000 mg/m³ concentration for 24 h/day from day 7 to day 14 of pregnancy. Additional groups of 3 rats were exposed to o-xylene at 150, 1500, or 3000 mg/m³ concentrations for 2 h only on the 18th day of pregnancy. In this latter group of rats exposed to o-xylene 18th day of pregnancy, the o-xylene concentration in the blood of the rats was proportional to that in the atmosphere. The solvent crossed the placenta; it was present in the fetal blood and amniotic fluid. All the 3 xylene isomers inhaled at the highest concentration brought about toxic effects in the mother animals. All the 3 isomers brought about the retardation of fetal development: a decrease in the weight of the fetuses, an increase in the incidence of the symptoms of skeletal retardation, a decrease in the activity of different enzymes, succinic dehydrogenase, alkaline- and acid phosphatase and glucose 6-phosphatase, characteristic features of the functional maturity of the nephron. Retardation of the fetuses was dose-dependent, but also dependent on the chemical structure of the particular isomer; their effectiveness was para-, ortho- and meta-xylene in the decreasing order of potency. None of the isomers proved to be teratogenic. Meta- and para-xylene inhalation at the highest concentration increased the incidence of extra ribs. Preimplantation fetal loss was increased by meta- and para-xylene, meta-xylene at the highest concentration interfered with the process of implantation, while para-xylene exposure resulted in an increased postimplantation loss of the fetuses. Ortho-xylene inhalation was without effect on the incidence of the extra ribs, either on implantation, or on the pre- and postimplantation fetal losses.     

The effect of dietary o,p'-DDT on ureagenesis from ammonia by isolated rat hepatocytes.

The herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) has a low-to-moderate toxicity in animals; however, high doses of 2,4,5-T have been shown to cause various toxic effects in mammals. Although this compound can be rapidly eliminated from the body by renal transport, there are circumstances wherein large amounts of this compound persist in the plasma and are accumulated by the kidney for prolonged periods of time. In order to determine the nature of this retention, 2,4,5-T binding to plasma proteins and renal tissue has been examined. The present results indicate that 2,4,5-T is bound extensively to plasma protein which could limit renal clearance of the herbicide. In addition, 2,4,5-T is bound to the microsomal and cytosol fractions of the renal cortex. One site has been found for 2,4,5-T binding to the microsomes. This site has an association constant (K_a) of 2.4 × 10³m^?1 and a binding capacity (n) of 17.5 μmol/g protein. Two 2,4,5-T binding sites have been found for the cytosol fraction. The first is a high affinity (K_a1 = 1.5 × 10⁴m^?1) and low capacity (n₁ = 4.48 μmol/g protein) site, while the second is a low affinity (K_a2 = 0.04 × 10³m^?1) and high capacity (n₂ = 630 μmol/g protein) site. These renal binding sites could explain the retention of 2,4,5-T in the kidney and may play a role in the nephrotoxicity of this herbicide.     

Anticholinesterase activity of the unsymmetric bisquaternary 6-aminoquinoline salt NSC-176319

The anticholinesterase activity of the unsymmetric bisquaternary 6-aminoquinoline salt NSC-176319 (QB) was studied in vitro. QB proved to be a noncompetitive inhibitor of both acetylcholinesterase (or true cholinesterase) and butyrylcholinesterase (or pseudocholinesterase) having a K₁ = 0.5 × 10^?6M for acetylcholinesterase and 1.5 × 10^6?M for butyrylcholinesterase. Further, QB inhibited esterase activity of murine plasma in a noncompetitive manner (K_i = 4.2 × 10^?6M). The inhibition was instantaneous in onset and did not diminish with prolonged incubation of the drug and enzyme. All mice treated intravenously with 2 mg QB/kg died within 5 min. Prior to death, mice developed severe parasympathomimetic effects and convulsions. Although the parasympathomimetic effects were diminished by atropine sulfate pretreatment, death could only be prevented by barbiturate anesthesia.     

Stimulation of rat liver 3-hydroxy-3-methylglutaryl-coenzyme a reductase activity by o,p′-DDD

To investigate the mechanism by which o,p′-DDD (2,2-bis[2-chlorophenyl-4-chloro-phenyl]-1,1-dichloroethane; Mitotane) produces hypercholesterolemia in man, we studied the effect of the drug on hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity in reverse light-cycled rats. o,p′-DDD markedly stimulated reductase activity in vivo and in vitro in a dose-dependent manner. This effect was not associated with demonstrable adrenocortical toxicity or changes in plasma corticosterone concentrations. Thus, o,p′-DDD may elevate circulating cholesterol levels in man by increasing endogenous cholesterol synthesis. In addition, the o,p′-DDD-treated rat may serve as a useful model for testing other agents for the ability to suppress endogenous cholesterol synthesis and lower circulating cholesterol levels.     

Effects of dietary cabbage,brussels sprouts, Illicium verum,Schizandra chinensis and alfalfa on the benzo[a]pyrene metabolic system in mouse liver

Male C57B16 mice were fed on diets containing either 20% cabbage, 20% Brussels sprouts, 20% alfalfa, 5% Schizandra chinensis or 5% Illicium verum (two Chinese medicinal herbs) or on a chow or purified basal diet for 14 days after a 1-wk equilibration period on the basal diet. Liver microsomal fractions were assayed for cytochrome P-450 content, aryl hydrocarbon hydroxylase (AHH) and epoxide hydrolase (EH). Liver microsome-mediated benzo[a]pyrene (BP) metabolism (with and without an EH inhibitor, 1,2-epoxy-3,3,3-trichloropropane) was analysed by HPLC. Liver weights of the animals fed on Brussels sprouts and I. verum were significantly increased compared with those of the animals fed on basal diets. S. chinensis induced a 3-fold increase in cytochrome P-450 (P < 0.05). Although P-450 induction in the other groups was as high as 1.8-fold (for chow), statistical significance was not established. Chow induced AHH activity 2.2-fold (P < 0.05), while S. chinensis and alfalfa induced 1.6-fold and 1.7-fold increases, respectively, in AHH activity, although neither increase was statistically significant. EH was stimulated significantly in the following order: I. verum (2.1-fold) > chow (1.7-fold) >S. chinensis (1.6-fold) > Brussels sprouts (1.4-fold). Total levels of BP metabolism and phenol II (primarily 3-hydroxybenzo[a]pyrene) formation were closely associated for each dietary treatment. Total BP metabolism was significantly increased (2.1-fold) in the chow-fed group and increased 1.6-fold in the S. chinensis group (P > 0.05). No increase was seen with the other diets. Phenol II formation relative to total metabolites was significantly increased for the S. chinensis and I. verum groups compared to the basal group. Diet-related variations in phenol production relative to total metabolism were eliminated by addition of the EH inhibitor to the incubation media.     

Effects of the tumor inhibitor, vernolepin, and of its thioether adduct, on the activity of catechol O-methyltransferase in vitro.

The activity of cat erythrocyte lysate catechol O-methyltransferase (COMT) in vitro is shown to be amenable to control by a variety of reagents including an SH reactive tumor inhibitor (vernolepin), its non-SH reactive derivative (the bis-n-propanethiol adduct of vernolepin), n-propanethiol itself, and the organic solvent, methanol. The ability of the adduct to modify COMT activity extends to all other sources examined (partially purified rat liver COMT and 78,000 g supernatant from rat liver, kidney, spleen and brain). Alterations in kinetic parameters (apparent K_m and Vmax) were observed when the adduct of vernolepin enhanced cat erythrocyte COMT activity.