Curcuma drugs and curcumin regulate the expression and function of P-gp in Caco-2 cells in completely opposite ways.

Curcumin is a phenolic compound isolated from rhizomes of C. longa, C. aromatica and other Curcumas except C. zedoaria. Recently, both curcumin and Curcumas have become prevalent as supplement. P-gp has been reported as an important determinant for drug absorption in small intestine. In this study, Caco-2 cell monolayers were treated with methanol extracts of Curcumas (0.1 mg/ml) or curcumin (30 microM) for 72h to investigate the relationship between the potential affects of Curcumas and curcumin on P-gp. [(3)H]-digoxin and rhodamine 123 were used to evaluate P-gp activity. All Curcumas significantly increased the activity of P-gp by up-regulating the expressions of P-gp protein and MDR1 mRNA levels. Interestingly, contrary to Curcumas, curcumin treatment inhibited the activity of P-gp with a decrease in P-gp protein and MDR1 mRNA expression levels. Curcumas might alter the pharmacokinetics of co-administrated drugs by up-regulating the function and expression levels of intestinal P-gp. However, curcumin has no relationship with the inductive effect of Curcumas since curcumin showed an opposite effects. Caution should be exercised when Curcumas or curcumin are to be consumed with drugs that are P-gp substrates because Curcumas and curcumin might regulate the function of P-gp in completely opposite ways.

Genetic polymorphism of bile acid CoA: amino acid N-acyltransferase in Japanese individuals.

In the present study, we identified three novel single nucleotide polymorphisms (SNPs), 147C>T in exon 2 (silent), 602G>C in exon 3 (Arg201Pro), and 1134C>T in exon 4 (silent), in the gene of bile acid CoA: amino acid N-acyltransferase (BAAT) by resequencing the entire coding region and the exon-intron junctions of 100 Japanese individuals. The allelic frequencies were 0.005 for 147C>T, 0.095 for 602G>C, and 0.015 for 1134C>T. The two known SNPs, 59G>A (Arg20Gln, rs1572983) and UTR1513G>A (rs2229594), were detected at a frequency of 0.500 and 0.425, respectively. In the haplotype analysis for the 59G>A and 602G>C polymorphisms, the allelic frequency of 59G-602G, 59G-602C, 59A-602G and 59A-602C was 0.405, 0.095, 0.500 and 0.000, respectively. On the other hand, the allelic frequency of the nonsynonymous SNP 602G>C was 0.194 in a Caucasian population.

Regulation of cytochrome P450 2E1 under hypertonic environment through TonEBP in human hepatocytes.

Whereas the liver as well as the other organs are continually exposed to the change of osmotic status, it has never been investigated whether activities and gene expressions of drug-metabolizing enzymes, including cytochromes P450, are dependent on osmotic change in the liver. In the present study, we determined that CYP2E1 is induced under hypertonic environments at a transcriptional level in human primary hepatocytes, as assessed by cDNA microarray and real time-reverse transcription-polymerase chain reaction analyses. Both a protein level and the catalytic activity of CYP2E1 were consistently increased in response to hypertonic conditions. In promoter-reporter assay, it was demonstrated that -586 to -566 in the CYP2E1 5'-flanking region was necessary for 2E1 promoter activation by hypertonic stimulation. It is noteworthy that tonicity-response element (TonE) consensus sequence was found at -578 to -568 in human CYP2E1 5'-flanking region, and electrophoretic mobility shift assay demonstrated the interaction of TonE binding protein (TonEBP) with TonE motif of CYP2E1 promoter. Furthermore, cotransfection of a CYP2E1 promoter construct with wild-type TonEBP expression vector enhanced promoter activity under both isotonic and hypertonic conditions, whereas dominant-negative TonEBP suppressed an induction of CYP2E1 promoter activity. These results indicate that the level of CYP2E1 is induced by hypertonic condition via TonEBP transactivation. The present study suggests that osmotic status may influence individual responses to the substrate of CYP2E1.

Effects of irsogladine on P450-isoform specific activities in human hepatic microsomes.

The effects of irsogladine (CAS 84504-69-8) on P450-isoform specific activities in human hepatic microsomes were examined. Irsogladine had little effects on coumarin hydroxylation (CYP2A6), 7-benzyloxyresorufin O-debenzylation (CYP2B6), S-mephenytoin hydroxylation (CYP2C19), bufuralol hydroxylation (CYP2D6), chlorzoxazone hydroxylation (CYP2E1) and nifedipine oxidation (CYP3A4) at concentrations ranging from 10 to 50 pmol/L. However, it inhibited 7-ethoxyresorufin O-deethylation (CYP1A2) and tolbutamide hydroxylation (CYP2C9) with the Ki values of 276 and 156 micromol/L, respectively. This suggests that it is a weak inhibitor of these isoforms. Because the plasma concentrations of irsogladine in humans are much lower than these Ki values, it is unlikely that irsogladine causes drug interactions with other drugs.

Effects of etodolac on P450 isoform-specific activities in human hepatic microsomes.

The effects of etodolac (CAS 41340-25-4) on P450 isoform-specific activities in human hepatic microsomes were examined. Etodolac had little effect on 7-ethoxyresorufin O-deethylation (CYP1A2), coumarin hydroxylation (CYP2A6), 7-benzyloxyresorufin O-debenzylation (CYP2B6), S-mephenytoin hydroxylation (CYP2C19), bufuralol hydroxylation (CYP2D6), chlorzoxazone hydroxylation (CYP2E1) and nifedipine oxidation (CYP3A4) at concentrations ranging from 10 to 50 micromol/L. Etodolac inhibited tolbutamide hydroxylation (CYP2C9) with the Ki value of 64 micromol/L, suggesting that it is a weak inhibitor of CYP2C9. The in vivo drug interaction was predicted from the in vitro data using the [I]/([I] + Ki) value. Because the value was calculated to be almost 1, it is not likely that etodolac causes the drug interactions with the CYP2C9 substrates.

Pharmacokinetics of the new pyrimidine derivative NS-7, a novel Na+/Ca2+ channel blocker. 2nd communication: tissue distributions, placental transfer and milk secretion of radioactivity after a single intravenous 14C-NS-7 injection to rats.

Tissue distribution, placental transfer and secretion of radioactivity in milk were studied after a single intravenous administration of 0.2 mg/kg of 14C-NS-7 (4-(fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride, CAS 178429-67-9), a novel Na+/Ca2+ channel blocker, to rats. Except for white fat in male and female rats, tissue radioactivity concentrations 5 min after administration were 2 to 100 times the plasma values, evidence that the drug is widely distributed throughout the body. Five minutes after administration the highest concentration was in the lung followed in order by the adrenal gland, kidney and thyroid gland. Concentrations in the cerebral cortex, striatum and cerebellum, the target organs of NS-7, were similar and 10 to 18 times the plasma concentrations in the male and female rats. Radioactivity concentrations in the lungs decreased rapidly. The pancreas had the highest concentration 2 h after administration. Concentrations decreased in all the tissues examined as the plasma concentration decreased. Maternal and fetal tissue radioactivity concentrations were determined after intravenous injection of 14C-NS-7 to pregnant rats on the 18th day of gestation. Radioactivity was well and rapidly distributed to the maternal tissues, and concentrations in all the tissues tested were higher than the plasma concentrations. In the amniotic fluid, however, the concentration was lower than in the plasma. In all the fetal tissues tested, radioactivity reached a maximum 1 h after administration. The respective fetal blood and whole body concentrations were 2 to 6 and 11 to 13 times the maternal plasma concentration. Of the fetal tissues tested the liver had the highest radioactivity. Decreases in fetal tissue radioactivity concentrations paralleled the decrease in the maternal plasma. More than 90% of the radioactivity present in the placenta and fetal whole body 1 and 24 h after administration was due to the unchanged drug. After intravenous injection of 14C-NS-7 (0.2 mg/kg) to lactating rats on the 10-14th day after parturition, radioactivity was excreted rapidly into the milk, reaching a maximum that was 4 to 6 times the plasma value 1 h after injection.

Pharmacokinetics of the new pyrimidine derivative NS-7, a novel Na+/Ca2+ channel blocker. 1st communication: plasma concentrations and excretions after a single intravenous 14C-NS-7 injection to rats, dogs and monkeys.

Plasma concentration profiles and excretion were investigated after a single intravenous injection of 14C-NS-7 (4-(fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride, CAS 178429-67-9), a novel Na+/Ca2+ channel blocker, to rats, dogs and monkeys. Plasma protein binding of this drug was determined in vitro and in vivo. AUC0-infinity values for radioactivity and NS-7 after the intravenous administration of 14C-NS-7 to male rats increased with the dose, namely from 0.04 to 5 mg/kg (radioactivity) and from 0.2 to 5 mg/kg (NS-7), indicating the linearity of the drug's pharmacokinetics. Plasma concentrations of the unchanged drug after the intravenous injection of 0.2 mg/kg 14C-NS-7 decreased biexponentially, respective t1/2 beta values being 15.9 h in the male and 22.4 h in the female rats. The t1/2 beta values difference in the males and females might be due to sex differences in NS-7 metabolism. Urinary and fecal excretions of radioactivity within 168 h of administration were 33.0 and 61.4% of the dose in the male and 35.0 and 53.2% in the female rats. No radioactivity was detected in air exhaled from the males and females collected for 168 h after NS-7 administration. Within 24 h of administration, respective biliary excretions for the male and female rats were 26.1 and 11.9% of the dose. Of this excreted radioactivity, 34.9% was reabsorbed in the males. NS-7 plasma concentrations decreased biexponentially after intravenous administration of 0.2 mg/kg 14C-NS-7 to dogs and monkeys. The elimination half-life was 18 h for the dogs and 9.52 h for the monkeys. Urinary and fecal excretions of radioactivity within 168 h of administration were 24.2 and 70.0% of the dose for the dogs, and 63.3 and 24.8% for the monkeys. These species differences in excretion may be due to differences in urinary metabolite compositions. In vitro protein binding of NS-7 showed no marked species differences and was independent of the NS-7 concentration. Binding of 14C-NS-7 in the sera of rats, dogs, monkeys and humans was 90.7%, 73.5% 79.0% and 87.1%, respectively. Binding to human serum albumin, alpha 1-acid glycoprotein and lipoprotein was 56.2%, 45.4% and 79.5%, in the range of 4-40 ng/ml. In vivo binding in rat serum 5 min, 6 h and 24 h after the intravenous injection of 14C-NS-7(0.2 mg/kg) ranged from 89.6 to 90.6%.