Cimetidine-induced androgenic failure causes cell death and changes in actin, EGF and V-ATPase immunoexpression in rat submandibular glands.

Submandibular gland (SMG) is responsive to androgens via androgen receptor (AR). We verified whether cimetidine induces androgenic dysfunction in SMG, and evaluated the structural integrity, cell death and immunoexpression of actin, EGF and V-ATPase in androgen-deficient SMG. Male rats received cimetidine (CMTG) and control animals (CG) received saline. Granular convoluted tubules (GCTs) diameter and number of acinar cell nuclei were evaluated. TUNEL and immunofluorescence reactions for detection of AR, testosterone, actin, EGF and V-ATPase were quantitatively analysed. In CG, testosterone immunolabelling was detected in acinar and ductal cells cytoplasm. AR-immunolabelled nuclei were observed in acinar cells whereas ductal cells showed AR-immunostained cytoplasm, indicating a non-genomic AR action. In CMTG, the weak testosterone and AR immunoexpression confirmed cimetidine-induced androgenic failure. A high cell death index was correlated with decreased number of acinar cells, GCTs diameter and EGF immunoexpression under androgenic dysfunction. Actin immunofluorescence decreased in the SMG cells, but an increased and diffuse cytoplasmic V-ATPase immunolabelling was observed in striated ducts, suggesting a disruption in the actin-dependent V-ATPase recycling due to androgenic failure. Our findings reinforce the androgenic role in the maintenance of SMG histophysiology, and point to a potential clinical use of cimetidine against androgen-dependent glandular tumour cells.

In vitro evaluation of the metabolic enzymes and drug interaction potential of triapine.

PURPOSE: To investigate the metabolic pathways of triapine in primary cultures of human hepatocytes and human hepatic subcellular fractions; to investigate interactions of triapine with tenofovir and emtricitabine; and to evaluate triapine as a perpetrator of drug interactions. The results will better inform future clinical studies of triapine, a radiation sensitizer currently being studied in a phase III study. METHODS: Triapine was incubated with human hepatocytes and subcellular fractions in the presence of a number of inhibitors of drug metabolizing enzymes. Triapine depletion was monitored by LC-MS/MS. Tenofovir and emtricitabine were co-incubated with triapine in primary cultures of human hepatocytes. Triapine was incubated with a CYP probe cocktail and human liver microsomes, followed by LC-MS/MS monitoring of CYP specific metabolite formation. RESULTS: Triapine was not metabolized by FMO, AO/XO, MAO-A/B, or NAT-1/2, but was metabolized by CYP450s. CYP1A2 accounted for most of the depletion of triapine. Tenofovir and emtricitabine did not alter triapine depletion. Triapine reduced CYP1A2 activity and increased CYP2C19 activity. CONCLUSION: CYP1A2 metabolism is the major metabolic pathway for triapine. Triapine may be evaluated in cancer patients in the setting of HIV with emtricitabine or tenofovir treatment. Confirmatory clinical trials may further define the in vivo triapine metabolic fate and quantify any drug-drug interactions.

Dose-Related Modulatory Effects of Polymeric Black Tea Polyphenols (PBPs) on Initiation and Promotion Events in B(a)P and NNK-Induced Lung Carcinogenesis.

Our understanding of dose-related effects of polymeric black tea polyphenols (PBPs), the most abundant polyphenols in black tea, is limited. In the present study, the effect of various doses of black tea (0.75, 1.5, and 3%)-derived PBP-rich extract on biochemical parameters and lung carcinogenicity in A/J mice was investigated. Pretreatment with PBPs showed the dose-related decrease in B(a)P-induced expression and activity of CYP1A1 in the liver while CYP1A2 expression and activity in the lung. Dose-dependent significant increase in PBP-mediated over-expression and activity of GSTs (alpha in the liver while pi in the lung) were observed in polyphenol-treated groups. Significant dose-related decrease in number and intensity of BPDE-DNA adducts were observed in liver and lung. Black tea (1.5%, 3%)-derived PBPs showed dose-mediated decrease in lung tumor incidence and multiplicity which was further correlated with different molecular markers like cell proliferation and apoptosis in B(a)P and NNK model. In conclusion, dose-dependent chemopreventive effects of PBPs, both anti-initiating (induction of phase II and inhibition of carcinogen-induced phase-I enzymes leading to decrease in BPDE-DNA adducts) and anti-promoting (decreased cell proliferation and increased apoptosis lowering incidence and/or multiplicity of lung lesions), were observed in A/J mice without significant toxicity.

In vitro metabolism of 4, 5-dimethoxycanthin-6-one by human liver microsomes and its inhibition on human CYP1A2.

AIMS: P. quassioides is a traditional Chinese medicine used for the treatment of gastroenteritis, snakebite, infection and hypertension in China. 4, 5-dimethoxycanthin-6-one is one of the main active canthinone alkaloid isolated from P. quassioides. The aim of this work was to identify the cytochrome P (CYP) 450 enzymes responsible for the metabolism of 4, 5-dimethoxycanthin-6-one (DCO) and to evaluate the inhibitory effect of DCO on CYP activity in human liver microsomes (HLM) in vitro. MATERIALS AND METHODS: the CYP isoforms responsible for DCO metabolism and the inhibitory effects of DCO on CYP activity was studied in HLM. KEY FINDINGS: The in vitro metabolic enzyme of DCO was CYP3A4 (mediated the formation of metabolites M1-M5), CYP2C9 (mediated the formation of metabolites M1-M3, M6 and M8) and CYP2D6 (mediated the formation of metabolite M3) in HLM. Furthermore, the present work found that DCO uncompetitively inhibited CYP1A2-mediated phenacetin O-deethylation with an IC50 value of 1.7µM and a Ki value of 2.6µM. SIGNIFICANCE: The results suggested that the metabolic interaction should be existed when the substrate drugs of CYP1A2 were co-administered with DCO or traditional Chinese medicine containing it, such as the extract of P. quassioides and Kumu injection.

Inhibition of CYP3A4 and CYP1A2 by Aegle marmelos and its constituents.

1. Aegle marmelos (bael) is a popular tree in India and other Southeast Asian countries. The fruit is usually consumed as dried, fresh or juice, and is reported to have a high nutritional value and many perceived health benefits. Despite its edible nature and therapeutic properties, no studies are reported regarding its effects on major drug metabolizing enzymes. 2. This study was aimed to evaluate the inhibitory potential of methanolic extract of A. marmelos fruit and its constituents (three furanocoumarins, namely marmelosin, marmesinin and 8-hydroxypsoralen, and 1 alkaloid, aegeline) towards major Cytochrome P450 enzymes (CYP3A4, 2D6, 1A2, 2C9 and 2C19) using human liver microsomes and recombinant CYPs. 3. The methanolic extract and marmelosin was found to be competitive and time-dependant inhibitor of CYP3A4. While reversible and non-competitive inhibition was observed for CYP1A2. Time-dependent inhibition of CYP3A4 was not affected by the addition of reduced glutathione. Marmesinin showed moderate inhibition of CYP3A4 and 1A2, while aegeline was a very weak inhibitor of CYP3A4 and showed no inhibition for CYP1A2 isoform. No significant inhibition of recombinant CYP2D6, 2C9, and 2C19 was seen with the extract or its constituents. 4. This is the first report of CYP3A4 and CYP1A2 inhibition by A. marmelos extract and one of its furanocoumarins, marmelosin. Further studies are warranted to determine if acute or prolonged use of bael fruit could affect the pharmacokinetics of drugs that are substrates of CYP3A4 or CYP1A2.

Effects of suberoylanilide hydroxamic acid on rat cytochrome P450 enzyme activities.

Vorinostat (suberoylanilide hydroxamic acid, SAHA) is the first approved histone deacetylase (HDAC) inhibitor for the treatment of cutaneous T-cell lymphoma after progressive disease following two systemic therapies. The rats were randomly divided into SAHA groups (low, medium and high dosage) and control group. The SAHA group rats were given 12.3, 24.5, and 49 mg/kg SAHA, respectively, by continuous intragastric administration for 7 days. The influence of SAHA on the activities of CYP450 isoforms CYP2B6, CYP1A2, CYP2C19, CYP2D6 and CYP2C9 were evaluated by cocktail method, they were responsed by the changes of pharmacokinetic parameters of bupropion, phenacetin, tolbutamide, metroprolol and omeprazole. The five probe drugs were given to rats through intragastric administration, and the plasma concentration were determined by UPLC-MS/MS. The result of SAHA group compared to control group, there were statistical pharmacokinetics difference for bupropion, phenacetin, tolbutamide and metroprolol. Continuous intragastric administration for 7 days may induce the activities of CYP2C19 of rats, inhibit CYP1A2 and slightly inhibit CYP2B6 and CYP2D6 of rats. This may give advising for reasonable drug use after co-used with SAHA. The results indicated that drug co-administrated with SAHA may need dose adjustment. Furthermore, continuous intragastric administration of SAHA for 7 days, liver cell damaged, causing liver cell edema, in liver metabolism process.

To cipro or not to cipro: bilateral achilles ruptures with the use of quinolones.

Ciprofloxacin and other fluoroquinolones are commonly used broad-spectrum antimicrobial agents for treating bacterial infections. This class of antibiotic drugs has uncommon adverse effects that include tendonitis, tendon ruptures, and other tendon abnormalities. We describe a patient with spontaneous bilateral complete Achilles tendon rupture after ciprofloxacin treatment. Surgical repair was performed successfully, and the patient completed physical rehabilitation without incident. Care should be exercised when selecting pharmaceutical agents to maintain a positive benefit-to-risk balance.

[Application of Cocktail Probe Drugs for Detecting Influences of Raw and Processed Phellodendri Cortex on Cytochrome P450 Isoforms].

OBJECTIVE: To research and compare the influences of raw and processed Phellodendri Cortex on the cytochrome P450 four isoforms by Cocktail probe drugs, and to explore the processing principle of Phellodendri Cortex. METHODS: SD rats were randomly divided into raw group,processed with rice-wine group, processed with salt-water group and blank control group, which were given raw decoction, processed with rice-wine decoction, processed with salt-water decoction (3.24 g/kg) and normal saline respectively for one week, then given the mixture of four probe drugs on the 8th day, and soon after the blood samples were obtained through the orbits at a series of time-points. HPLC method was used to determine the concentrations of probe drugs in rat plasma, and pharmacokinetic parameters were estimated by DAS3.0. The effect of raw and processed Phellodendri Cortex on cytochrome P450 were judged indirectly by the pharmacokinetic parameters. RESULTS: Compared with the blank control group, the t½ significantly increased of theophylline in raw and processed with salt-water group. The CL/F significantly decreased and AUC(0-t) AUC(0-∞). significantly increased of theophylline in raw and processed with rice-wine groups. The t(½) AUC(0-∞) and AUC(0-∞) significantly decreased and CL/F significantly increased of dapsone in raw, processed with rice-wine and processed with salt-water group. The AUC(0-t) significantly increased of chlorzoxazone in raw and processed with salt-water group. The t(½), AUC(0-∞). and AUC(0-t) significantly decreased and CL/F significantly increased of chlorzoxazone in processed with rice-wine group. The AUC(0-t), significantly decreased of tolbutamide in raw, processed with rice-wine and processed with salt-water groups. CONCLUSION: The raw Phellodendri Cortex can inhibit CYP1A2, induce CYP3 A4 and also is need to make a further research work on CYP2C9 and CYP2E1. Meanwhile, it also can change the activities of cytochrome P450 after processed with rice-wine and salt-water. The Phellodendri Cortex processed with rice-wine can reduce the inhibitory effect of CYP1A2 and enhance induction of CYP3A4, it provides reference and basis to make an interpretation about Phellodendri Cortex processed with rice-wine.

In vitro effect of important herbal active constituents on human cytochrome P450 1A2 (CYP1A2) activity.

This study was designed to investigate eight herbal active constituents (andrographolide, asiaticoside, asiatic acid, madecassic acid, eupatorin, sinensetin, caffeic acid, and rosmarinic acid) on their potential inhibitory effects on human cytochrome P450 1A2 (CYP1A2) activity. A fluorescence-based enzyme assay was performed by co-incubating human cDNA-expressed CYP1A2 with its selective probe substrate, 3-cyano-7-ethoxycoumarin (CEC), in the absence or presence of various concentrations of herbal active constituents. The metabolite (cyano-hydroxycoumarin) formed was subsequently measured in order to obtain IC50 values. The results indicated that only eupatorin and sinensetin moderately inhibited CYP1A2 with IC50 values of 50.8 and 40.2 µM, while the other active compounds did not significantly affect CYP1A2 activity with IC50 values more than 100 µM. Ki values further determined for eupatorin and sinensetin were 46.4 and 35.2 µM, respectively. Our data indicated that most of the investigated herbal constituents have negligible CYP1A2 inhibitory effect. In vivo studies however may be warranted to ascertain the inhibitory effect of eupatorin and sinensetin on CYP1A2 activity in clinical situations.

Inhibition of human cytochrome P450 enzymes by Bacopa monnieri standardized extract and constituents.

Bacopa monnieri and the constituents of this plant, especially bacosides, possess various neuropharmacological properties. Like drugs, some herbal extracts and the constituents of their extracts alter cytochrome P450 (CYP) enzymes, causing potential herb-drug interactions. The effects of Bacopa monnieri standardized extract and the bacosides from the extract on five major CYP isoforms in vitro were analyzed using a luminescent CYP recombinant human enzyme assay. B. monnieri extract exhibited non-competitive inhibition of CYP2C19 (IC50/Ki = 23.67/9.5 µg/mL), CYP2C9 (36.49/12.5 µg/mL), CYP1A2 (52.20/25.1 µg/mL); competitive inhibition of CYP3A4 (83.95/14.5 µg/mL) and weak inhibition of CYP2D6 (IC50 = 2061.50 µg/mL). However, the bacosides showed negligible inhibition of the same isoforms. B. monnieri, which is orally administered, has a higher concentration in the gut than the liver; therefore, this herb could exhibit stronger inhibition of intestinal CYPs than hepatic CYPs. At an estimated gut concentration of 600 µg/mL (based on a daily dosage of 300 mg/day), B. monnieri reduced the catalytic activities of CYP3A4, CYP2C9 and CYP2C19 to less than 10% compared to the total activity (without inhibitor = 100%). These findings suggest that B. monnieri extract could contribute to herb-drug interactions when orally co-administered with drugs metabolized by CYP1A2, CYP3A4, CYP2C9 and CYP2C19.

Fennel and raspberry leaf as possible inhibitors of acetaminophen oxidation.

In addition to CYP2E1, several CYP isoenzymes, notably CYP1A2, 2D6, and 3A4, are suggested to contribute in acetaminophen oxidation and formation of the hepatotoxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). The in vitro CYP2E1 inhibitory potentials of fennel and raspberry leaf, herbs previously found to inhibit CYP1A2, 2D6, and 3A4 activities in vitro, were investigated. Extracts from commercially available herbal products were incubated with recombinant cDNA-expressed human CYP2E1. A validated LC/MS/MS methodology was applied for determination of 6-hydroxychlorzoxazone formation with disulfiram used as a positive inhibitory control. CYP2E1 IC50 inhibition constants were found to be 23 ± 4 and 27 ± 5 µg/ml for fennel and raspberry leaf, respectively, constants significantly lower than those presented in the literature for other herbal extracts. Together with previous findings, the presented in vitro data for CYP2E1 inhibition suggest that fennel and raspberry leaf have a significant potential of inhibiting all the major metabolic pathways for acetaminophen oxidation and NAPQI formation. Both herbs should be further investigated for their in vivo ability of inhibiting acetaminophen oxidation and NAPQI formation.

In vitro inhibitory effect of piperlonguminine isolated from Piper longum on human cytochrome P450 1A2.

Piperlonguminine (PL), a major alkaloid isolated from Piper longum fruits, shows several biological activities including anti-tumor, anti-hyperlipidemic and anti-inflammatory effects. Although there have been studies of the biological effects of PL, the potential drug-interaction effect of PL following evaluation of inhibitory effects of cytochrome P450 (CYP) activities was not investigated. Here, to investigate the inhibitory effects of PL on the activities of CYP isoforms, CYP inhibition assays were conducted using a cocktail of probe substrates in pooled human liver microsome (HLMs) and human recombinant cDNA-expressed CYP. PL strongly inhibited CYP1A2-mediated phenacetin O-deethylation with an IC50 value of 8.8 µM, as NADPH-independent inhibition, while other CYPs were not significantly inhibited. A Lineweaver-Burk plot resulted in the inhibition mechanism of PL being divided into two different modes, reversible competitive inhibition in a low concentration range of 0-16 µM with a Ki value of 1.39 µM and uncompetitive inhibitory behavior at a high concentration range of 16-40 µM. In addition, PL only decreased CYP 1A2-catalyzed phenacetin O-deethylase activity with IC50 values of 10.0 µM in human recombinant cDNA-expressed 1A2, not 1A1. Overall, this is the first investigation of potential herb-drug interactions associated with PL conducted by identifying the competitive inhibitory effects of PL on CYP1A2 in HLMs.

In vitro inhibition of human CYP1A2, CYP2D6, and CYP3A4 by six herbs commonly used in pregnancy.

Black elderberry, cranberry, fennel, ginger, horsetail, and raspberry leaf, herbs frequently used in pregnancy, were investigated for their in vitro CYP1A2, 2D6, and 3A4 inhibitory potential. Aqueous or ethanolic extracts were made from commercially available herbal products, and incubations were performed with recombinant cDNA-expressed human CYP enzymes in the presence of positive inhibitory controls. Metabolite formation was determined by validated LCMS/MS or HPLC methodologies. IC50 inhibition constants were estimated from CYP activity inhibition plots using non-linear regression. The most potent inhibition was shown for fennel towards CYP2D6 and 3A4 with respective IC50 constants of 23 ± 2 and 40 ± 4 µg/ml, horsetail towards CYP1A2 with an IC50 constant of 27 ± 1 µg/ml, and raspberry leaf towards CYP1A2, 2D6, and 3A4 with IC50 constants of 44 ± 2, 47 ± 8, and 81 ± 11 µg/ml, respectively. Based on the recommended dosing of the different commercial herbal products, clinically relevant systemic CYP inhibitions could be possible for fennel, horsetail, and raspberry leaf. In addition, fennel and raspberry leaf might cause a clinically relevant inhibition of intestinal CYP3A4. The in vivo inhibitory potential of these herbs towards specific CYP enzymes should be further investigated.

Identification and characterization of psoralen and isopsoralen as potent CYP1A2 reversible and time-dependent inhibitors in human and rat preclinical studies.

Naturally occurring furanocoumarin compounds psoralen (PRN) and isopsoralen (IPRN) are bioactive constituents found in herbaceous plants. They are widely used as active ingredients in several Chinese herbal medicines. In this study, the CYP1A2 inhibitory potential of PRN and IPRN was investigated in rats in vitro and in vivo as well as in human liver microsomes. Both compounds exhibited reversible and time-dependent inhibition toward rat microsomal cyp1a2. The IC(50), k(inact), and K(I) values were 10.4 ± 1.4 µM, 0.060 ± 0.002 min(-1), and 1.13 ± 0.12 µM for PRN, and 7.1 ± 0.6 µM, 0.10 ± 0.01 min(-1), and 1.95 ± 0.31 µM for IPRN, respectively. In human liver microsomal incubations, potent reversible CYP1A2 inhibition was observed for both compounds, with IC(50) values of 0.26 ± 0.01 µM and 0.22 ± 0.03 µM for PRN and IPRN, respectively. However, time-dependent inhibition was only observed for IPRN, with kinact and KI values of 0.050 ± 0.002 min(-1) and 0.40 ± 0.06 µM, respectively. Coadministration with PRN or IPRN significantly inhibited cyp1a2 activity in rats, with the area under the curve (AUC) of phenacetin increasing more than 5-fold. Simcyp simulation predicted that PRN would cause 1.71- and 2.12-fold increases in the phenacetin AUC in healthy volunteers and smokers, respectively. IPRN, on the other hand, would result in 3.24- and 5.01-fold increases in phenacetin AUCs in healthy volunteers and smokers, respectively. These findings represent the first detailed report comparing the potential drug-drug interactions of PRN and IPRN, and provide useful information for balancing safe and efficacious doses of PRN and IPRN.

Inhibition of CYP1 by berberine, palmatine, and jatrorrhizine: selectivity, kinetic characterization, and molecular modeling.

Cytochrome P450 (P450, CYP) 1 family plays a primary role in the detoxification and bioactivation of polycyclic aromatic hydrocarbons. Human CYP1A1, CYP1A2, and CYP1B1 exhibit differential substrate specificity and tissue distribution. Berberine, palmatine, and jatrorrhizine are protoberberine alkaloids present in several medicinal herbs, such as Coptis chinensis (Huang-Lian) and goldenseal. These protoberberines inhibited CYP1A1.1- and CYP1B1.1-catalyzed 7-ethoxyresorufin O-deethylation (EROD) activities, whereas CYP1A2.1 activity was barely affected. Kinetic analysis revealed that berberine noncompetitively inhibited EROD activities of CYP1A1.1 and CYP1B1.1, whereas palmatine and jatrorrhizine caused either competitive or mixed type of inhibition. Among protoberberines, berberine caused the most potent and selective inhibitory effect on CYP1B1.1 with the least Ki value of 44±16 nM. Berberine also potently inhibited CYP1B1.1 activities toward 7-ethoxycoumarin and 7-methoxyresorufin, whereas the inhibition of benzo(a)pyrene hydroxylation activity was less pronounced. Berberine inhibited the polymorphic variants, CYP1B1.3 (V432L) and CYP1B1.4 (N453S), with IC50 values comparable to that for CYP1B1.1 inhibition. Berberine-mediated inhibition was abolished by a mutation of Asn228 to Thr in CYP1B1.1, whereas the inhibition was enhanced by a reversal mutation of Thr223 to Asn in CYP1A2.1. This result in conjugation with the molecular modeling revealed the crucial role of hydrogen-bonding interaction of Asn228 on CYP1B1.1 with the methoxy moiety of berberine. These findings demonstrate that berberine causes a selective CYP1B1-inhibition, in which Asn228 appears to be crucial. The inhibitory effects of berberine on CYP1B1 activities toward structurally diverse substrates can be different.

Inhibitory effects of gypenosides on seven human cytochrome P450 enzymes in vitro.

Among the various possible causes for drug interactions, pharmacokinetic factors such as inhibition of drug-metabolizing enzymes, especially cytochrome P450 (CYP) enzymes, are regarded as the most frequent and clinically important. Gypenosides is widely used as functional food and over-the-counter drug in East Asia. In this study, the in vitro inhibitory effects of gypenosides on the major human CYP enzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) activities in human liver microsomes were examined using liquid chromatography-tandem mass spectrometry. Gypenosides showed the strongest inhibition of CYP2D6, followed by CYP2C8, CYP3A4 and CYP2C9. The IC50 values were 1.61 µg/mL, 20.06 µg/mL, 34.76 µg/mL (CYP3A4/midazolam), 46.73 µg/mL (CYP3A4/testosterone), and 54.52 µg/mL, respectively. Gypenosides exhibited competitive inhibition of CYP2D6 (Ki=1.18). In conclusion, Gypenosides might cause herb-drug interactions via inhibition of CYP2D6. An in vivo study is needed to examine this further.

[Preclinical investigation of pharmaceuticals impact against cytochrome P450 activity and prognosis of substrate affinity as means for providing substrate therapy safety].

Tricyclic antidepressants, not influencing the P450 3A4 activity, are safe in combination with drugs of other groups used in the treatment of comorbid patients. Azaphen is is one of the agents most widely used in the clinical practice. The in vitro electrochemical analysis showed that pipofezin (azaphen) was not a substrate, inductor, and/or inhibitor of cytochrome P450 CYP3A4 isoenzymes. The Guzar programme computer modelling and the literature data demonstrated the substrate affinity of pipifezin to CYP1A2.

Biopharmaceutical characterization of decursin and their derivatives for drug discovery.

Angelica gigas Nakai and its components are known to have neuroprotective, antiplatelet, and anticancer activities. The present study evaluated the in vitro and in vivo biopharmaceutical characterization of Angelica gigas component substances, including decursin (the main substance), decursinol angelate (decursin isomer), JH714 (ether form of decursin) and epoxide decursin (epoxide form of decursin). Decursin, decursinol angelate and JH714 exhibited acceptable metabolic stability (>50%) in liver microsomes from human and higher bound fraction (>90%) in human plasma operating ultrafiltration. Decursin and decursinol angelate in CYP1A2 and CYP2C19 indicated less than 50% CYP activity, suggesting inhibition of the CYP isoforms using Vivid® CYP screening kit. JH714 only showed an apparent permeability coefficient of <10 × 10⁻6 cm/s in MDCK cells, suggesting that it is poorly absorbed. Blood brain barrier permeability was examined after oral administration to male Sprague-Dawley (SD) rats, and pharmacokinetic studies were performed after oral and intravenous administration of 10 mg/kg compounds. Decursin, decursinol angelate and JH714 showed ratios of compound concentration in brain with respect to plasma (Cbrain/Cplasma) of >1.5, suggesting good brain/plasma ratio at 0.5, 1, 3, and 5 h. In contrast, Cbrain/Cplasma was <0.5 for epoxide decursin. For all test compounds, >1.5% of the dose remained in GI tract after 8 h, and the excretion rate in urine was <0.5% which suggests that gastro intestinal tract may be major site of disposition following oral administration. Finally, these results may be useful for the design of dosage regimens of decursin and its derivatives.

Selective inhibitory effects of mollugin on CYP1A2 in human liver microsomes.

Mollugin originally isolated from Rubia cordifolia is a pharmacological compound for its anti-inflammation, anti-cancer, and anti-viral activity. In the present study, a cocktail probe assay was performed for determination of the selective inhibitory effect of mollugin on cytochrome P450 (CYP) enzymes in human liver microsomes (HLM). Incubation of isoform-specific substrate probes CYPs with mollugin (0-25µM) in HLM resulted in strong inhibition of CYP1A2-catalyzed phenacetin O-deethylation, showing IC(50) values of 1.03 and 3.55µM without and with pre-incubation, respectively. Mollugin-caused inhibition of phenacetin O-deethylation was concentration-dependent in HLMs, but not time-dependent. In addition, the Lineweaver-Burk plot indicated a typical competitive inhibition. Inhibitory effects of mollugin on human recombinant cDNA-expressed CYP1A1 and 1A2 were comparable. Taken together, the results suggested that mollugin might cause herb-drug interaction through selective inhibition of CYP1A2 in humans receiving herbal medications, including R. cordifolia.

[Influence of jinlingzi powder with different compatibility on activity of cytochrome P1 A2 from rat liver microsomes].

To illustrate the compability rule of Jinlingizi powder, by investigating the effects of Jinlingzi Powder with different compatibility on the enzymatic activity of cytochrome P1 A2 (CYP1A2) from rat liver microsome. The different compability of Jinlingizi powder is designed, based on the orthogonal array L9 (3(4)). In vitro test, rat liver microsomes incubation system is applied to detect the 50% inhibitory concentraton of Jinlingzi powder with different compatibility to cytochrome P1A2 (CYP1A2) enzyme. In vivo experiments, rats is treated orally with the different compability of Jinlingizi powder for 5 days, then be injected with probe drug phenacetin. The biosample from liver tissue is obtained by microdialysis probe, then analysisd by HPLC. The concentration-time data are modulated by software WinNonlin. IC50 data show no significant inhibitory activty to cytochrome P1 A2. Acetaminophen and phenacetin PK parameters indicate that the different compability of Jinlingizi powder can modulate the CYP 1A2 mediated metabolism, which is associate with the compatibility of Jinlingzi powder.