The multidrug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily of membrane transporters. MDR1 acts as an energy-dependent efflux pump that exports its substrates out of cells. MDR1 was originally isolated from resistant tumor cells as part of the mechanism of multidrug resistance, but over the last decade, it has been elucidated that human MDR1 is also expressed throughout the body to confer intrinsic resistance to the tissues by exporting unnecessary or toxic exogeneous substances or metabolites. A number of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics and pharmacodynamics. In 2000, Hoffmeyer et al. performed a systemic screening for MDR1 polymorphisms and detected 15 single nucleotide polymorphisms (SNPs). They also indicated that a polymorphism in exon 26 at position 3435 (C3435T), a silent mutation, affected the expression level of MDR1 protein in duodenum, and thereby the intestinal absorption of digoxin. To date, the genotype frequencies of C3435T have been investigated extensively using a larger population and interethnic difference has been elucidated, and a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical studies on MDR1 genotype-related MDR1 expression and pharmacokinetics have also been performed around the world; however, results were not always consistent with Hoffmeyer’s report. In this review, published reports are summarized for the future individualization of pharmacotherapy based on MDR1 genotyping. In addition, recent investigations have raised the possibility that MDR1 and related transporters play a fundamental role in regulating apoptosis and immunology, and in fact, there are reports of MDR1-related susceptibility to inflammatory bowel disease, HIV infection and renal cell carcinoma. Herein, these issues are also summarized, and the current status of the knowledge in the area of pharmacogenomics of other transporters is briefly introduced.
The inhibitory effect of galloyl pedunculagin (GP) isolated from Platycarya strobilacea on the activity and autophosphorylation of Ca2+- and phospholipid-dependent protein kinase (C-kinase) was examined in vitro. It was found that (i) GP inhibited the activity (phosphorylation of complement C3 from guinea pig) of C-kinaseα (rat brain) in a dose-dependent manner with an ID50 of approx. 0.12 μM; (ii) GP at lower doses (ID50=approx. 6 nM) inhibited autophosphorylation of C-kinaseα; and (iii) the GP-induced inhibition of autophosphorylation of C-kinaseα and its enzyme activity was a manner non-competitive to ATP. Similar inhibitory effect of GP on autophosphorylation of recombinant human C-kinaseη (rhC-kinaseη) and its phosphorylating activity was observed. These results suggest that GP is an effective autophosphorylation inhibitor of these two C-kinase isoforms (α and η) in vitro. In addition, the CD analysis suggests that the proline-containing six amino acid residues (PVLTPP) including a threonine residue (autophosphorylation site) at the C-terminal region (positions 635—640) of C-kinaseα may be one of the GP-binding sites.
The effect of activins A, AB, and B on hepatocyte growth factor (HGF) synthesis stimulated by 12-O-tetradecanoylphorbol β-acetate (TPA) was studied in MRC-5 human lung fibroblasts. Activins A, AB, and B inhibited the increase in HGF secretion induced by TPA in different dose-dependent manners and potencies. At 5 ng/ml, activins A and AB inhibited the increase approximately 30% and 10%, respectively, and at 25 ng/ml both activins produced almost maximal inhibition, i.e., approximately 40%. Activin B caused 10% inhibition at 12 ng/ml, and at 25 ng/ml produced almost maximal inhibition, approximately 30%. Further analysis with activin A indicated that the inhibition was caused by decreased HGF mRNA levels, followed by decreased cellular HGF levels. At 25 ng/ml, activin A inhibited the increase in HGF in the cellular lysate and the increase in HGF mRNA level approximately 80% and 40%, respectively.
Extracellular matrix tenascin-X (TNX)-null mice, generated by disruption of the Tnx gene, display augmented invasion and metastasis of B16-BL6 melanoma tumor cells due to increased activities of matrix metalloproteinase (MMP)-2 and MMP-9. In this study, we investigated cell–matrix and cell–cell adhesions using TNX-null fibroblasts and wild-type fibroblasts. TNX-null fibroblasts exhibited a decreased attachment to fibronectin compared with that of wild-type fibroblasts. B16 melanoma cells were cocultured with wild-type or TNX-null fibroblasts, and the adhesion of B16 melanoma to the fibroblasts was assessed. B16 melanoma cells on wild-type fibroblasts proliferated and spread out in a horizontal direction, whereas those on TNX-null fibroblasts overlapped each other rather than migrating horizontally. These overlapping B16 melanoma cells on TNX-null fibroblasts peeled off faster than those on wild-type fibroblasts. To determine whether the decreased cell–matrix and cell–cell adhesions on TNX-null fibroblasts were due to increased MMP activity, the activities of MMPs in wild-type and TNX-null fibroblasts were compared by gelatinolytic assays. The analysis of MMPs from conditioned media demonstrated that almost the same levels of MMP activities were detected between wild-type and TNX-null fibroblasts. However, contrary to our expectations the activities of MMPs from conditioned media of B16 melanoma cells cocultured on TNX-null fibroblasts were rather reduced than those of B16 melanoma cells cocultured on wild-type. We concluded that the absence of TNX in the extracellular environment might play an important role in enhancement of the detachment of B16 melanoma cells.
FAT/CD36 is involved in various processes including uptake of fatty acid into the heart and of oxidized low density lipoprotein (LDL) into macrophages. Expression of the FAT/CD36 gene is regulated in a tissue-specific manner, and loss or inadequately regulated expression of FAT/CD36 is thought to be one of the causes of some diseases such as cardiomyopathy and atherosclerosis. We recently found that the mouse and human FAT/CD36 genes have two independent promoters. To elucidate the physiological significance of the two promoters, we characterized the peroxisome proliferator-activated receptor ligand-responsive new promoter that is located 14 kb upstream of the previously reported promoter of the human gene. We found several SNPs in this region some of which were found only when analyzing DNA samples from the patients lacking FAT/CD36 totally or in a cell-type-specific manner. However, we could not detect any negative effect of these SNPs on the transcription by transient transfection analysis, suggesting that the identified SNPs alone are not directly linked to low transcriptional activities.
The inducer of differentiation of human promyelocytic leukemia HL-60 cells is commonly accepted to have potential therapeutic importance. Verticinone, one of the major isosteroidal alkaloids from the bulbus of Fritillaria ussuriensis, was found to inhibit the growth of HL-60 cells by inducing these cells to differentiate toward granulocytes. Importantly, the combination of verticinone with all-trans retinoic acid (ATRA), a well-known inducer of HL-60 cells into granulocytic lineages, was more effective than either alone, suggesting its therapeutic use in minimizing the effective dose of ATRA.
Postprandial hypertriglyceridemia, as well as postprandial hyperglycemia, are important factors contributing to the development of cardiovascular disease in patients with type 2 diabetes. Nateglinide is a recently approved antidiabetic that suppresses postprandial hyperglycemia by stimulating the early phase of insulin secretion. In the present study, we investigated the effects of nateglinide on postprandial hypertriglyceridemia in obese Zucker fatty (ZF) rats and non-obese diabetic Goto–Kakizaki (GK) rats. Administration of an oral fat load caused marked hypertriglyceridemia with a peak at 2 h in ZF and GK rats. Nateglinide (50 mg/kg) significantly suppressed the increase of plasma triglycerides after fat loading in both types of rat (ΔAUC [0—4 h]: 15±69 mg·h/dl for nateglinide vs. 838±100 mg·h/dl for vehicle in ZF rats; p<0.01, 81±22 mg·h/dl for nateglinide vs. 164±17 mg·h/dl for vehicle in GK rats; p<0.01). In contrast, other antidiabetic agents (voglibose and glibenclamide) did not show a significant effect on the increase of triglycerides after fat loading. The triglyceride components suppressed by nateglinide were mainly at the origin and in the pre β subfraction on agarose gel electrophoresis, suggesting that chylomicrons and very low density lipoproteins were decreased. Plasma insulin levels were significantly increased at 30 min in nateglinide-treated rats, but not in voglibose- or glibenclamide-treated rats. These results suggest that nateglinide not only suppresses postprandial hyperglycemia, but also suppresses postprandial hypertriglyceridemia, by promoting rapid and pulsatile insulin secretion in patients with type 2 diabetes.
Sho-saiko-to extract, a Chinese herbal medicine, is widely used for treatment of chronic hepatitis in Japan. However, it is not clear what conditions Sho-saiko-to extract improves hepatic inflammation and fibrosis. We therefore induced various stages of liver injury in model rats and administered Sho-saiko-to extract. We then evaluated the liver inflammation and liver fibrosis-improving effects of Sho-saiko-to extract. The liver injury model rats were produced by administration of various doses of dimethylnitrosamine (DMN) and Sho-saiko-to extract was administered to these rats. Then the liver inflammation and fibrosis-improving effects of Sho-saiko-to extract were evaluated according to L-asparate aminotransferase (AST), L-alanine aminotransferase (ALT), liver retinoid levels, levels of hydroxyproline, Transforming Growth Factor-β (TGF-β), and the liver fibrosis area. These indicators depended on the total doses of DMN. The ability of Sho-saiko-to extract to improve liver inflammation and fibrosis was limited to the following levels of the respective parameters: AST levels (234—264 U/l), ALT levels (208—232 U/l), TGF-β levels (1102—1265 pg/g liver tissue), hydroxyproline levels (633—719 nmol/g liver tissue), and liver fibrosis area (9.7—10.6 times for normal rat). These findings suggested that Sho-saiko-to extract is effective in the treatment of liver inflammation and fibrosis up to a certain degree of severity, but it produces no improvement in more severe cases.
We examined the hemodynamic property of T-1032 (methyl 2-(4-aminophenyl)-1,2-dihydro-1-oxo-7-(2-pyridylmethoxy)-4-(3,4,5-trimethoxy-phenyl)-3-isoquinoline carboxylate sulfate), a novel selective phosphodiesterase type 5 (PDE5) inhibitor, and evaluated the chronic effect of T-1032 on cardiac remodeling and its related death in monocrotaline (MCT)-induced pulmonary hypertensive rats. T-1032 (1, 10, 100 μg/kg, i.v.) significantly reduced mean arterial pressure (MAP) and right ventricular systolic pressure (RVSP) without a change in heart rate. The change in RVSP was more potent than that in MAP with 1 μg/kg T-1032 treatment (RVSP: −8.2±1.2%, mean arterial pressure: −5.7±1.2%), and reductions in RVSP and MAP reached a peak at doses of 1 and 10 μg/kg, respectively. In contrast, nitroglycerin (0.1, 1, 10 μg/kg, i.v.) and beraprost (0.1, 1 μg/kg, i.v.) did not cause a selective reduction in RVSP at any dose. When T-1032 (300 ppm in diet) was chronically administered, it delayed the death, and significantly suppressed right ventricular remodeling (T-1032-treated: 0.318±0.021 g, control: 0.401±0.013 g, p<0.05). Our present results suggest that T-1032 selectively reduces RVSP, and resulting in the suppression of right ventricular remodeling with a delay of the death in MCT-induced pulmonary hypertensive rats.
Effects of co-administration with the 5-HT2 receptor antagonist LY 53857 and the antidepressant mianserin on immobility time in the forced swimming test were investigated in mice. Mianserin did not affect the immobility time at ranges from 1—10 mg/kg, although it elicited anti-immobility effects at 20 mg/kg. Co-administration of the 5-HT2 receptor antagonist LY 53857 and a subactive dose of mianserin induced apparent anti-immobility effects. Since mianserin facilitates noradrenaline (NA) release from nerve terminals via inhibition of α2 receptors, the blockade of the 5-HT2 receptor may increase the antidepressant effect of drugs modifying NA levels in the synaptic cleft.
The aim of this study was to investigate the effect of Moutan Cortex on acetaminophen (AAP)-induced toxicity in human Chang liver cells. Cells were incubated with AAP (0—30 mM) to evaluate the drug’s ability to reduce cytoviability. For the cells treated with 10, 20 and 30 mM AAP, LDH leakage was 39.8%, 49.0% and 57.6%, respectively. Administration of Moutan Cortex reduced cytotoxicity in a dose-dependent manner. Glutathione (GSH) concentration in human liver cells decreased significantly after exposure to 20 (p<0.05) and 30 mM (p<0.01) AAP, and increased (p<0.05) if incubated with AAP and Moutan Cortex. The ability of AAP to inhibit mitochondrial function and its counteraction by Moutan Cortex was also evaluated. Moutan Cortex showed dose-dependent increases in MTT metabolism and ATP levels in AAP-treated cells. The DNA content of AAP-treated cells increased with the treatment of Moutan Cortex. These observations demonstrate that Moutan Cortex may significantly attenuate AAP-induced toxicity. It can be considered a cytoprotective agent in this in vitro model of drug toxicity.
In this study, prooxidant and antioxidant status in liver homogenates and their mitochondrial fractions were investigated in both chronic and chronic plus acute ethanol-treated rats. Increases in serum transaminase activities, as well as increases in total lipid, triglyceride, malondialdehyde (MDA) and diene conjugate (DC) levels and decreases in glutathione (GSH), vitamin E and vitamin C levels, have been observed in liver homogenates following chronic ethanol treatment (20% ethanol, v/v as drinking water for 3 months), but CuZn-superoxide dismutase (CuZnSOD), glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities remained unchanged in postmitochondrial fractions. When an acute dose of ethanol (5 g/kg, i.p.) was given rats which had received ethanol chronically, serum transaminase activities and hepatic lipid and MDA and DC levels increased further, but GSH levels and antioxidant enzymes decreased more compared to the chronic ethanol-treated rats. There were no significant differences in the levels of MDA, DC and protein carbonyl and the activities of GSH-Px and GST in the hepatic mitochondrial fraction of rats following both chronic and chronic plus acute treatments. Mn-superoxide dismutase (MnSOD) activities increased in both groups, but mitochondrial GSH levels decreased only after chronic plus acute treatment. Therefore, we suggest that the increase in MnSOD activity may play an important role in the regulation of mitochondrial susceptibility against ethanol-induced oxidative stress.
A series of novel 2-phenyl-3-substituted quinazolin-4(3H)-ones have been synthesized by treating methyl-N-(2-phenyl quinazolin-3-yl-4(3H)-one) dithiocarbamate with different amines, the starting material dithiocarbamate was synthesized from anthranilic acid. The title compounds were investigated for analgesic, anti-inflammatory and antibacterial activities. All the test compounds exhibited significant activity, the compounds A1, A2 and A3 shown more potent analgesic activity, and the compound A3 shown more potent anti-inflammatory activity than the reference standard diclofenac sodium.
The anti-inflammatory activities of several novel oximes and O-acyl oximes that we synthesized have been reported based on carrageenan-induced rat foot-pad swelling assay and histamine-induced rat vascular permeability assay. A cyclooxygenase (COX)-1 inhibitory effect has also been reported for 4′-piperidinoacetophenone and 4′-morpholinoacetophenone oximes and their O-acyl derivatives. To further search for more effective non-steroidal anti-inflammatory or anti-allergic drugs, 1-hydroxylamino-1-(4′-piperidinophenyl) ethane (P-HA) and 1-hydroxylamino-1-(4′-morpholinophenyl) ethane (M-HA) were synthesized from the corresponding oximes with sodium cyanoborohydride, and N,O-diacetyl hydroxylamines (P-HA-Ac and M-HA-Ac) were prepared from these hydroxylamines using acetyl chloride. These hydroxylamines and N,O-diacetyl hydroxylamines clearly exhibited inhibitory effects on mouse carrageenan-induced foot-pad swelling induced by oral administration (150, 37.5 mg/kg). An oral dose of P-HA-Ac (150 mg/kg) significantly inhibited the mouse anaphylactic reaction to ovalbumin measured by the abdominal wall (AW) method. Percutaneous administration of P-HA and M-HA significantly inhibited 2,4-dinitrofluorobenzene (DNFB)-induced contact hypersensitivity reaction (type IV) in mice at a dose of 0.5 and 0.1 mg/ear, respectively. All tested hydroxylamines and N,O-diacetyl hydroxylamines clearly inhibited both COX-1 and COX-2 enzyme activities with IC50 values of 1.9—28.7 and 1.6—2.9 μM against COX-1 and COX-2, respectively. Hydroxylamines (P-HA and M-HA) also showed a 5-lipoxygenase inhibitory effect.
To evaluate the antihyperlipidemic activities of Orengedokuto (OT) and Daio-Orengedokuto (DOT), the inhibitory effects of these polyprescriptions on HMG-CoA reductase and pancreatic lipase and on the rat hyperlipidemic model induced by Triton WR-1339 were measured. OT potently inhibited HMG-CoA reductase but did not inhibit lipase. Among their ingredients, Coptidis Rhizoma was the most potent inhibitor, followed by Rhei Rhizoma. The HMG-CoA reductase-inhibitory activity of 80% EtOH extract was superior to that of water extract. However, DOT potently inhibited HMG CoA-reductase as well as pancreatic lipase. In the rat hyperlipidemic model induced by Triton WR-1339, OT and DOT decreased serum total cholesterol and low-density lipoprotein cholesterol levels. DOT also decreased serum triglyceride levels, but OT did not decrease it. These results suggest that the antihyperlipidemic activity of DOT may originate from the inhibition of pancreatic lipase as well as HMG-CoA reductase.
The present work was performed to elucidate the active moiety of a sesquiterpene lactone, taraxinic acid-1′-O-β-D-glucopyranoside (1) from Taraxacum coreanum NAKAI on the cytotoxicity of various cancer cells. Based on enzymatic hydrolysis and MTT assay, the active moiety should be attributed to the aglycone taraxinic acid (1a), rather than the glycoside (1). Taraxinic acid exhibited potent antiproliferative activity against human leukemia-derived HL-60. In addition, this compound was found to be a potent inducer of HL-60 cell differentiation as assessed by a nitroblue tetrazolium reduction test, esterase activity assay, phagocytic activity assay, morphology change, and expression of CD14 and CD66b surface antigens. These results suggest that taraxinic acid induces the differentiation of human leukemia cells to monocyte/macrophage lineage. Moreover, the expression level of c-myc was down-regulated during taraxinic acid-dependent HL-60 cell differentiation, whereas p21CIP1 and p27KIP1 were up-regulated. Taken together, our results suggest that taraxinic acid may have potential as a therapeutic agent in human leukemia.
The MeOH extract of the leaves of rosemary (Rosmarinus officinalis L.) completely inhibited the motility of cultured epimastigotes of Trypanosoma cruzi at the concentration of 2 mg/ml after 2 h of incubation. Activity-guided fractionation of the MeOH extract has resulted in the isolation of three triterpene acids, betulinic, oleanolic and ursolic acids. Ursolic acid stopped the movement of all T. cruzi epimastigotes at the minimum concentration (MC100) of 40 μg/ml (88 μM) after 48 h of incubation. Oleanolic acid was less active (MC100: 250 μg/ml, 550 μM) and betulinic acid was practically inactive.
Four steviol (ent-kaurene-type diterpenoid) glycosides, stevioside, rebaudiosides A and C, and dulcoside A, have been isolated from Stevia rebaudiana BERTONI. These compounds showed strong inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice. The 50% inhibitory dose of these compounds for TPA-induced inflammation was 54.1—291.6 μg/ear. Furthermore, at 1.0 and 0.1 mg/mouse of stevioside mixture, the mixture of these compounds markedly inhibited the promoting effect of TPA (1 μg/mouse) on skin tumor formation initiated with 7,12-dimethylbenz[a]anthracene (50 μg/mouse).
We have recently reported that evodiamine can suppress in vitro invasion and lung metastasis by colon 26-L5 carcinoma cells. To extend our study, we examine here the anti-invasive and metastatic effects of evodiamine on Lewis lung carcinoma (LLC) and B16-F10 melanoma in addition to colon 26-L5 carcinoma. Critical structures of evodiamine for the activities were also evaluated by comparison with compounds possessing structures similar to that of evodiamine. Evodiamine concentration-dependently inhibited the invasion of B16-F10, LLC and colon 26-L5 cells with IC50 values of 2.4 μM, 4.8 μM and 3.7 μM, respectively. Pre-treatment of colon 26-L5 cells with evodiamine before inoculation into mice caused significant suppression of the liver metastasis as well as the lung metastasis. Lung metastasis by LLC is also inhibited significantly by pre-exposure to evodiamine. When the anti-migratory activity of evodiamine was compared with that of evodiamine-like compounds, rutaecarpine lacking a methyl group at N-14 and a hydrogen at C-13b exhibited much less effect than evodiamine. In addition, reserpine, having β-configurated hydrogen at C-13b, inhibited tumor cell migration more potently than yohimbine, having α-configurated hydrogen at the same position. These results suggest that evodiamine may be useful as a leading compound for agents in tumor metastasis therapy. Also, the presence of a methyl group at N-14 and the configuration of hydrogen at C-13b may be responsible for the inhibitory activities of evodiamine.
The effect of treatment with Saeng-Maek-San (SMS) Complex (SMS1 or SMS2) upon rat hepatocytes exposed to alcohol was investigated. We compared the serum biochemistry and liver histology of rats administered both alcohol and SMS to control rats treated with alcohol alone. SMS treatment resulted in a significant reduction in the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and triglycerides (TG) compared to the control rats. In contrast, expression levels of alcohol dehydrogenase (ADH) were increased. Electron microscopy indicated that administration of SMS preserved the structure of organelles, including the nucleus and mitochondria. In addition, lipid droplets and secondary lysosomes were observed in the control rats. These data suggest that SMS represents an excellent candidate for protection of rat hepatocytes from alcohol-mediated damage.
The objective of this study was to evaluate the reduction in skin barrier function caused by direct current iontophoresis by measuring resistance in the short term. The experiments were carried out using rat abdominal skin in vivo. The resistance was measured every 125 ms and analyzed using a two-compartment model consisting of surface and skin resistance. Moreover, the initial value and the rate constant of each resistance were calculated with the non-linear approximation program. The proposed method could evaluate the reduction in barrier function from the initial value and the rate constant of surface resistance with high sensitivity and accuracy. Using this proposed method, the effects of the conductivity of an adhesive pad, voltage, the distance between electrodes and the area of electrode were examined. The increase in conductivity of the adhesive pad decreased the initial value since the rate constant increased. The reduction in barrier function depends on voltage. Although the barrier function decreased up until an electrode distance of 1 cm, it increased beyond 1 cm. These phenomena contributed to the current pass portion in the skin because the resistance was in the order of the stratum corneum, epidermis and dermis. The initial value decreased with increasing electrode area. However, the rate constant was little affected since the current density of a topical electrode adjacent to the other electrode was high.
The possibility of pharmacokinetic interactions between Sho-saiko-to extract powder (TJ-9), the most widely used traditional Chinese herbal (Kampo) medicine in Japan, and carbamazepine (CBZ), an important anti-epileptic drug, was examined in rats. There was no significant difference in the protein binding of CBZ in serum obtained before and after the single oral administration of TJ-9. The addition of TJ-9 to normal hepatic microsomes inhibited CBZ-10,11-epoxylase activity in a concentration-dependent manner. Liver weight, amounts of P450 and cytochrome b5 in hepatic microsomes and the formation of carbamazepine-10,11-epoxide (CBZ-E), an active metabolite of CBZ, by microsomes were not influenced by 2-week repeated oral pretreatment with TJ-9 (1 g/kg/d), although pretreatments with phenobarbital (80 mg/kg/d, i.p.) significantly increased these parameters. The simultaneous oral administration of TJ-9 (1 g/kg) significantly decreased the peak plasma concentration of CBZ and the area under the concentration–time curve of CBZ-E, and lengthened the time to reach the peak concentration of CBZ after oral administration of CBZ. Two-week repeated oral pretreatment with TJ-9, however, did not affect the plasma concentration–time profile or any pharmacokinetic parameter of CBZ or CBZ-E. Also, a single oral administration of TJ-9 (1 g/kg) significantly delayed gastric emptying. These results indicated that the simultaneous oral administration of TJ-9 with CBZ to rats decreased the gastrointestinal absorption of CBZ, at least in part, by delaying gastric emptying, without affecting the metabolism of CBZ.
Animal models prepared by treatment with toxic compounds such as a carbon tetrachloride have been used to examine drug disposition in hepatic diseases. However, it is possible that these compounds accumulate and cause damage to other organs as they are administered systemically. In this study, we used the liver surface application technique to deliver a toxic compound to the liver to prepare an appropriate animal model in which only the liver is significantly damaged. To restrict the absorption area in the liver, a cylindrical diffusion cell was attached to the liver surface of male Wistar rats. Twenty-four hours after direct addition of carbon tetrachloride to the diffusion cell, plasma levels of glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT), and hepatic malondialdehyde (MDA) concentration were increased, while there were no changes in plasma creatinine or renal MDA level. On the other hand, not only GOT, GPT and hepatic MDA, but also creatinine and renal MDA levels were markedly increased by p.o. and i.p. administration of carbon tetrachloride, suggesting renal damage. These results indicated that the animal models of liver damage prepared by utilizing drug delivery techniques to accumulate toxic compounds in the liver would enable us to investigate the precise effects of hepatic disorder on drug disposition.
Cephradine-containing ethylcellulose microparticles (MPC) were prepared by the solvent evaporation method. Chitosan-coated MPC (Chi-MPC) were prepared by doping MPC with viscous chitosan solution and subsequently drying. When fluorescein isothiocyanate (FITC)-labeled chitosan-coated ethylcellulose microparticles without drug were administered intraduodenally, they moved slowly in the intestine, that is, most of them were retained at the upper and middle parts of the small intestine for more than 8 h, which is considered due to mucoadhesive properties of coated chitosan. When MPC and Chi-MPC was incubated at 37 °C in the JP 14 second fluid, pH 6.8, both released the drug slowly with similar release rates. Cephradine solution and suspension, MPC and Chi-MPC were administered intraduodenally to investigate intestinal drug absorption. Only Chi-MPC suppressed the initial plasma level and maintained the plasma concentration for a long time up to 24 h, suggesting Chi-MPC would be useful for prolonged intestinal absorption of cephradine.
Stoichiometric evaluation of the radical scavenging activity of O-substituted derivatives at the C-2 position of ascorbic acid (AA) was conducted. Their reaction with a stable radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH), under an acidic condition was assessed by the colorimetric method. 2-O-α-D-Glucopyranosyl-L-ascorbic acid (AA-2G) and a series of 6-O-acyl-2-O-α-D-glucopyranosyl-L-ascorbic acids (6-Acyl-AA-2G) had long-term radical scavenging activity against DPPH. The reaction of AA-2G or 6-Acyl-AA-2G with DPPH was very slow when compared with AA. However, one molecule of these derivatives consumed approximately three molecules of DPPH radicals at the end of the experiment (2 h). In contrast, one molecule of AA scavenged two molecules of DPPH radicals, and the reaction ended in the short time (<10 min). The quantity of radicals quenched by AA-2G and 6-Acyl-AA-2G was superior to that of AA in a long-term reaction.
Experiments with volunteers in Singapore have demonstrated that coffee drinking increases urinary hydrogen peroxide levels (Long, Halliwell, Free Rad. Res., 32, 463—467 (2000)). We re-examined the effect of coffee drinking of healthy Japanese subjects on urinary hydrogen peroxide levels. A cup of brewed or canned coffee commercially available in Japan generated 120—420 μmol hydrogen peroxide in incubation in a neutral medium at 37 °C for 6 h. The increased levels were higher than those obtained from a cup of green tea extract or a glass of red wine. After the subject drank a cup of coffee, apparent hydrogen peroxide levels (μmol/g creatinine) in urine collected 1—2 h after coffee drinking increased 3—10-fold compared to the levels before coffee drinking. The increased urinary hydrogen peroxide levels are likely derived mainly from 1,2,4-benzenetriol excreted in urine, because the major component that generates hydrogen peroxide is found to be 1,2,4-benzenetriol, and storing urine collected after coffee drinking increased hydrogen peroxide levels in a time-dependent fashion. Total hydrogen peroxide equivalent levels excreted in 3 h-urine after coffee drinking were estimated to be 0.5—10% that of coffee consumed. A residual amount of hydrogen peroxide may be retained or consumed in human bodies.
We investigated the production of interleukin-1 (IL-1) activity by Kupffer cells (KC) from mice treated with a neutral mannan fraction (WNM) or an acidic mannan fraction (WAM025) from baker's yeast (Saccharomyces cerevisiae) in vivo and in vitro. The mice administered WAM025 showed an increase in the number of KC and the IL-1 production compared with mice administered WNM. In an in vitro stimulation assay using KC from a normal mouse, it was also found that WAM025 displayed an increase in IL-1 production. Diisopropyl fluorophosphate completely inhibited the production of IL-1 by KC from the mice administered WAM025.
Pyruvate dehydrogenase kinase 4 (PDK4) mRNA was identified as a transcript that was rapidly and generally induced by fibrates in various tissues of the mouse. The time course of induction was much faster than those of typical peroxisome proliferator-activated receptor α (PPARα)-regulated peroxisomal mRNAs. Rapid and efficient induction of PDK4 mRNA in various tissues would inactivate pyruvate dehydrogenase and stimulate fatty acid oxidation at the whole body level, leading to enhanced utilization of serum fatty acids and triglycerides. This metabolic switching mechanism can explain the early phase of the fibrate-induced decrease in the serum levels of triglycerides. Furthermore, the muscle in the fibrate-induced early state with limited activity of pyruvate dehydrogenase and low levels of fatty acids will utilize proteins as an energy source and extensive degradation of proteins may lead to myopathy or rhabdomyolysis.