Effect Of Pgp Research Articles

Ginseng polysaccharide components attenuate obesity and liver lipid accumulation by regulating fecal microbiota and hepatic lysine degradation

The increasing incidence of obesity has led to widespread attention in the exploration of natural ingredients. Ginseng polysaccharides (PGP), the main components from Panax ginseng, have been reported potential effect to attenuate obesity and regulate lipid metabolism. In this study, we found that PGP inhibited the high-fat diet (HFD)-induced weight gain, fat ratio and fat tissue weight after 8-week administration. Serum and liver lipid analysis showed that PGP decreased the levels of triglyceride and total cholesterol, which was mediated by the inhibition of key genes for fatty acid and cholesterol metabolisms. Metabolomics studies showed that the inhibitory effect of PGP on liver lipid accumulation was significantly correlated with its regulation of citric acid cycle and lysine degradation. PGP regulated the expression of genes related to lysine degradation in both liver tissue and hepatocytes. In addition, PGP reshaped the composition of fecal microbiota at the genus and species levels in obese mice. Spearman's correlation analysis demonstrated that Staphylococcus sciuri, Staphylococcus lentus, and Pseudoflavonifractor sp. An85 may be the potential targets that PGP maintains the abundance of l-lysine against obesity. It concluded that PGP can attenuate obesity and liver lipid accumulation by regulating fecal microbiota and hepatic lysine degradation.

A Novel Ambroxol-Derived Tetrahydroquinazoline with a Potency against SARS-CoV-2 Proteins.

We report synthesis of a novel 1,2,3,4-tetrahydroquinazoline derivative, named 2-(6,8-dibromo-3-(4-hydroxycyclohexyl)-1,2,3,4-tetrahydroquinazolin-2-yl)phenol (1), which was obtained from the hydrochloride of 4-((2-amino-3,5-dibromobenzyl)amino)cyclohexan-1-ol (ambroxol hydrochloride) and salicylaldehyde in EtOH. The resulting compound was produced in the form of colorless crystals of the composition 1∙0.5EtOH. The formation of the single product was confirmed by the IR and 1H spectroscopy, single-crystal and powder X-ray diffraction, and elemental analysis. The molecule of 1 contains a chiral tertiary carbon of the 1,2,3,4-tetrahydropyrimidine fragment and the crystal structure of 1∙0.5EtOH is a racemate. Optical properties of 1∙0.5EtOH were revealed by UV-vis spectroscopy in MeOH and it was established that the compound absorbs exclusively in the UV region up to about 350 nm. 1∙0.5EtOH in MeOH exhibits dual emission and the emission spectra contains bands at about 340 and 446 nm upon excitation at 300 and 360 nm, respectively. The DFT calculations were performed to verify the structure as well as electronic and optical properties of 1. ADMET properties of the R-isomer of 1 were evaluated using the SwissADME, BOILED-Egg, and ProTox-II tools. As evidenced from the blue dot position in the BOILED-Egg plot, both human blood-brain barrier penetration and gastrointestinal absorption properties are positive with the positive PGP effect on the molecule. Molecular docking was applied to examine the influence of the structures of both R-isomer and S-isomer of 1 on a series of the SARS-CoV-2 proteins. According to the docking analysis results, both isomers of 1 were found to be active against all the applied SARS-CoV-2 proteins with the best binding affinities with Papain-like protease (PLpro) and nonstructural protein 3 (Nsp3_range 207-379-AMP). Ligand efficiency scores for both isomers of 1 inside the binding sites of the applied proteins were also revealed and compared with the initial ligands. Molecular dynamics simulations were also applied to evaluate the stability of complexes of both isomers with Papain-like protease (PLpro) and nonstructural protein 3 (Nsp3_range 207-379-AMP). The complex of the S-isomer with Papain-like protease (PLpro) was found to be highly unstable, while the other complexes are stable.

1-hydroxy-6,6-Dimethyl-3-Phenyl-1,6-Dihydropyridine-2,5-Dione as a Promising Inhibitor of the SARS-CoV-2 Proteins: insight into the Crystal Structure, Hirshfeld Surface Analysis and Computational Study

In this work detailed studies of 1-hydroxy-6,6-dimethyl-3-phenyl-1,6-dihydropyridine-2,5-dione (1), which is of potential biological interest, are reported. The molecule of 1 is stabilized by O–H···O and two C–H···O hydrogen bonds. The former interaction yields a pseudo-aromatic hydrogen bonded five-membered ring. The overall crystal packing of 1 is mainly described by O–H···O hydrogen bonds and π···π interactions, yielding a 1D supramolecular ribbon-like chain. These chains are linked through weak C–H···O hydrogen bonds. The reciprocal favored intermolecular H···H/C/O and C···C contacts are main contributors to the total Hirshfeld surface of 1. The structure, electronic and optical properties of 1 were verified with the DFT calculations, which revealed that 1 is a strong electrophile with the most pronounced nucleophilic and electrophilic centers located on the carbonyl oxygen atoms and on the hydroxyl hydrogen atom, respectively. Values for the calculated polarizability and first-order hyperpolarizability parameters for a molecule of 1 are higher in comparison to those of urea. Bioavailability, druggability as well as absorption, distribution, metabolism, excretion and toxicity properties of 1 were evaluated using the SwissADME, BOILED-Egg and ProTox-II tools. It was established that for 1, the human blood-brain barrier penetration property is positive and gastrointestinal absorption property is high with the negative PGP effect on the molecule. Molecular docking was applied to examine the influence of this compound on a series of the SARS-CoV-2 proteins, of which 1 exhibits the best affinity behavior toward RdRp-RNA, nonstructural protein 14 (N7-MTase) and N protein (NCB site).

6-Amino-2-(4-fluorophenyl)-4-(trifluoromethyl)quinoline: Insight into the Crystal Structure, Hirshfeld Surface Analysis and Computational Study

In this work we report detailed structural and computational studies of 6-amino-2-(4-fluorophenyl)-4-(trifluoromethyl)quinoline (1). The structure is stabilized by the intramolecular N–H···N hydrogen bonds, C–H···F interactions, π···π interactions and C–F···F–C interactions. The listed interactions are also reflected on the Hirshfeld surfaces as well as the corresponding 2D fingerprint plots, which revealed that the crystal packing of 1 is mainly dictated by highly favored H···H and H···F contacts followed by also favored H···N, C···C and F···F contacts. The DFT calculations were performed to verify the structure of 1 as well as its electronic and optical properties. Compound 1 was predicted to exhibit preferred results for drug candidates in five parameters, namely lipophilicity, size, polarity, insolubility and flexibility. Furthermore, it was predicted that 1 is likely a potential inhibitor of family A G protein-coupled receptor and kinase; electrochemical transporter and voltage-gated ion channel; oxidoreductase, hydrolase, protease, family C G protein-coupled receptor and primary active transporter with the probabilities of 20.0%, 13.3% and 6.7%, respectively. At the same time, 1 was found to be active against Aryl hydrocarbon Receptor (AhR) and Mitochondrial Membrane Potential (MMP), hepatotoxic and mutagenic. According to the BOILED-Egg method for 1 the human blood-brain barrier (BBB) penetration property is negative and gastrointestinal absorption property is positive with the positive PGP effect on the molecule.

Phenotypic display of plant growth-promoting traits in individual strains and multispecies consortia of plant growth promoting rhizobacteria and rhizobia under salinity stress

The use of multispecies plant growth promoting rhizobacteria (PGPR) in conjunction with rhizobia is a favourable tool for mitigating salt stress to legumes. However there is a need to understand the synergistic effect of PGPR in consortia, while also demonstrating the PGP effect under salinity. In this study, we have evaluated PGPR bacteria belonging to Enterobacter, Pseudomonas and rhizobia, individually as well as in consortia for plant growth promoting traits viz. indole acetic acid (IAA), biofilm and siderophore production, under salt stress. Interestingly, several consortia demonstrated better stress tolerance and responded with increased PGPR effect suggesting synergy between these multispecies combinations. Present work reports promising novel combinations of soil isolates which show enhanced PGP traits in consortia that could mitigate salt stress.

Selected Rhizosphere Bacteria Help Tomato Plants Cope with Combined Phosphorus and Salt Stresses.

Plants are often challenged by multiple abiotic stresses simultaneously. The inoculation of beneficial bacteria is known to enhance plant growth under these stresses, such as phosphorus starvation or salt stress. Here, for the first time, we assessed the efficiency of selected beneficial bacterial strains in improving tomato plant growth to better cope with double stresses in salty and P-deficient soil conditions. Six strains of Arthrobacter and Bacillus with different reservoirs of plant growth-promoting traits were tested in vitro for their abilities to tolerate 2–16% (w/v) NaCl concentrations, and shown to retain their motility and phosphate-solubilizing capacity under salt stress conditions. Whether these selected bacteria promote tomato plant growth under combined P and salt stresses was investigated in greenhouse experiments. Bacterial isolates from Cameroonian soils mobilized P from different phosphate sources in shaking culture under both non-saline and saline conditions. They also enhanced plant growth in P-deficient and salt-affected soils by 47–115%, and their PGP effect was even increased in higher salt stress conditions. The results provide valuable information for prospective production of effective bio-fertilizers based on the combined application of local rock phosphate and halotolerant phosphate-solubilizing bacteria. This constitutes a promising strategy to improve plant growth in P-deficient and salt-affected soils.

Pharmacokinetic Modeling of the Impact of P-glycoprotein on Ondansetron Disposition in the Central Nervous System.

Modulation of 5-HT3 receptor in the central nervous system (CNS) is a promising approach for treatment of neuropathic pain. The goal was to evaluate the role of P-glycoprotein (Pgp) in limiting exposure of different parts of the CNS to ondansetron (5-HT3 receptor antagonist) using wild-type and genetic knockout rat model. Plasma pharmacokinetics and CNS (brain, spinal cord, and cerebrospinal fluid) disposition was studied after single 10mg/kg intravenous dose. Pgp knockout resulted in significantly higher concentrations of ondansetron in all tested regions of the CNS at most of the time points. The mean ratio of the concentrations between KO and WT animals was 2.39-5.48, depending on the region of the CNS. Male and female animals demonstrated some difference in ondansetron plasma pharmacokinetics and CNS disposition. Mechanistic pharmacokinetic model that included two systemic disposition and three CNS compartments (with intercompartmental exchange) was developed. Pgp transport was incorporated as an efflux from the brain and spinal cord to the central compartment. The model provided good simultaneous description of all data sets, and all parameters were estimated with sufficient precision. The study provides important quantitative information on the role of Pgp in limiting ondansetron exposure in various regions of the CNS using data from wild-type and Pgp knockout rats. CSF drug concentrations, as a surrogate to CNS exposure, are likely to underestimate the effect of Pgp on drug penetration to the brain and the spinal cord.

Assessment of the hepatocyte protective effects of gypenoside and its phosphorylated derivative against DHAV-1 infection on duck embryonic hepatocytes

BackgroundDuck viral hepatitis (DVH) is an acute disease of young ducklings with no effective veterinary drugs for treatment. Gynostemma pentaphyllum is a well-known traditional Chinese medicine that plays an important role in the treatment of various diseases. Gypenoside (GP), one of the main ingredients of Gynostemma pentaphyllum, was reported with good hepatoprotective effects. However, its low solubility limits its application in the clinics. To improve its solubility and bioactivity, a phosphorylated derivative of gypenoside (pGP) was prepared by the sodium trimetaphosphate-sodium tripolyphosphate (STMP-STPP) method. An infrared spectroscopy method was applied to analyse the structures of GP and pGP. Then, a methyl thiazolyl tetrazolium (MTT) colorimetric assay was applied to study the hepatocyte protective efficacy of these two drugs against duck hepatitis A virus type 1 (DHAV-1) infection, and qPCR, TUNEL labelling and flow cytometry methods were used to study the relevant hepatocyte protective in vitro.ResultsThe infrared spectroscopy detection results showed that the phosphorylation modification of GP was successful. The MTT colorimetric assay results showed that both GP and pGP possessed good hepatocyte protective efficacy in vitro, and pGP performed better than GP when the drug was added before or after virus inoculation. Furthermore, the qPCR results revealed that both drugs could effectively inhibit the adsorption (when adding GP and pGP pre-virus inoculation), replication and release of DHAV-1, and the viral inhibition rate of pGP was greater than that of GP. The subsequent TUNEL labelling and flow cytometry assays showed that both GP and pGP could significantly inhibit duck embryo hepatocyte apoptosis induced by DHAV-1, and the inhibition effect of pGP was much stronger than that of GP.ConclusionsGP exerts good hepatocyte protective efficacy not only by inhibiting the proliferation of DHAV-1 but also by inhibiting duck embryonic hepatocyte apoptosis induced by DHAV-1, and phosphorylation modification significantly improves the antiviral and the anti-apoptotic effects of GP. Therefore, pGP has the potential to be developed into a novel drug against DHAV-1 infection.

Cplx2 gene expression following semax or PGP administration under conditions of two experimental models of rat-brain ischemia

Complexin 2 is a cytosolic protein participating in synaptic-vesicle exocytosis. The RT-PCR technique was used in a real-time study of the dynamics of variation of expression of the Cplx2 gene that encodes this protein. The study was performed in the rat brain. Measurements under the conditions of incomplete global ischemia were performed during 1 day; measurements under the conditions of focal ischemia were carried out 3, 24, and 72 h after irreversible occlusion of the medial cerebral artery. The most significant decrease in Cplx2 transcripts under the conditions of incomplete global ischemia was observed in the hippocampus and the frontal cortex of rats 12 and 24 h after irreversible occlusion of the common carotid arteries, respectively. Under conditions of focal ischemia, a decrease in the content of Cplx2 transcripts was observed only in focal lesions of the frontoparietal cortex 24 h after occlusion. The effect of Semax neuroprotector peptide and its C-terminal fragment Pro-Gly-Pro on Cplx2 expression was examined under the model ischemia conditions. In the case of incomplete global ischemia, application of Semax compensated for the maximum decrease in Cplx2 expression in the frontal cortex and hippocampus in rats caused by lesions. However, the peptide had no effect when used in rats with focal ischemia. The effect of PGP on Cplx2 expression under conditions of experimental ischemia was more complicated and did not always coincide with the effect of Semax. The obtained results provide insight into the specific features of Cplx2 expression under the conditions of experimental brain ischemia and help to better understand the mechanisms of activity of peptide preparations.

Effect of glyprolines PGP and N-acetyl-PGP on the expression of cytokine genes during stress- and acetate-induced ulceration

We have studied the effects of glyprolines PGP and N-acetyl-PGP on cytokine gene expression during stress and acetate-induced ulceration. Levels of RNA in mononuclear cells in circulating blood were evaluated using reverse transcription polymerase chain reaction. Intranasal administration of PGP (3.7 μmol/kg) has had a significant protective effect against stress-induced (59.4%) and acetate-induced (78.5%) ulceration in rats. N-acetyl-PGP has not changed the area of stress-induced damage, but it tended to inhibit the development of acetate ulcers. We found that stress-induced damage of gastric mucosa is accompanied by an increase in TNFα transcription and a decrease in IL-4 transcription. The development of acetate ulcers is accompanied by a decrease in expression of a number of cytokines: IFNα, IFNγ, IL-2, IL-4, IL-6, IL-12, and TNFα. The protective effect of PGP is accompanied by an increase in expression of IL-6. When N-acetyl-PGP is administered, an increase in the expression of Th-1 and Th-2 cytokines have been observed: IFNα, IFNγ, and IL-4.

Change in cytokine profile of rats in protective antiulcer effects of glyprolines. Effects of glyprolines (PGP and N-acetyl-PGP) on expression of cytokine genes in ethanol ulcer formation

The effects of glyprolines (PGP and N-acetyl-PGP) on the expression of cytokine genes in the ethanol ulcer formation model have been investigated. Determination of the activity of mRNA in peripheral blood mononuclear cells has been performed using methods of reverse transcription and polymerase chain reaction. It has been shown that, in control animals, the formation of ethanol damages of gastric mucosa in some cases is accompanied by inhibition of transcription of IFN-α, IL-6, IL-12, and TNF-α and increased transcription of IFN-Γ, IL-8, IL-10. PGP reduces the injury area by 38%, which is accompanied by significantly increased gene expression of IL-1β. The peptide Ac-PGP does not change the area of ethanol ulcers but inhibits the transcription of IFN-α, TNF-α (p < 0.05), and IFN-Γ. Thus, the gastroprotective effect of PGP is probably mediated through IL-1β.

Effect of peptide Semax and its C-terminal fragment PGP on Vegfa gene expression during incomplete global cerebral ischemia in rats

Vascular endothelial growth factor (VEGF-A) is hypoxia-inducible signal glycoprotein. VEGF-A induces vascular endothelial cell proliferation, which leads to the reconstitution of the vascular network in brain regions damaged by ischemia. However, this protein is also involved in the processes of inflammation and edema in early stages of ischemia. The synthetic peptide Semax has neuroprotective and anti-inflammatory properties and is actively used in the treatment of cerebral ischemia. We have previously shown that Semax reduces vascular injury and activates the mRNA synthesis of neurotrophins and their receptors during global cerebral ischemia in rats. In this work, we studied the effect of Semax and its C-terminal Pro-Gly-Pro tripeptide on Vegfa mRNA expression in different regions of the rat brain after 0.5, 1, 2, 4, 8, 12 and 24 h, which is the irreversible occlusion of the common carotid arteries. It was shown that ischemia increases the levels of Vegfa mRNA in rat brains (4 h after occlusion in cerebellum, cerebral cortex, and hippocampus; 8 h after occlusion in the cortex and hippocampus; and 24 h after occlusion in the cortex). Treatment with Semax reduces the levels of Vegfa mRNA in the frontal cortex (4, 8 and 12 h after occlusion) and the hippocampus (2 and 4 h after occlusion). The effect of PGP on the Vegfa gene expression was almost negligible. It was shown that Semax prevents the activating effect of hypoxia on the expression of the Vegfa gene at early stages of global cerebral ischemia. In turn, an increase in the level of Vegfa mRNA in the hippocampus 24 h after occlusion and Semax administration apparently reflects the neuroprotective properties of the drug.

Влияние пептидов семакс и PGP на экспрессию генаVegfaу крыс в условиях неполной глобальной ишемии головного мозга

Vascular endothelial growth factor (VEGFA) is a hypoxia-inducible signal glycoprotein. VEGFA causes vascular endothelial cell growth and proliferation, that leads to the regeneration of vascular network in brain regions damaged by ischemia. However, this protein is involved in processes of inflammation and edema in early stages of ischemia. Synthetic peptide semax shows neuroprotective and anti-inflammatory properties and is actively used in the treatment of ischemia.We have previously shown that semax reduces vascular injury and activates the mRNA synthesis of neurotrophins and their receptors under global cerebral ischemia in rats. Here we have analyzed the effects of semax and its C-terminal Pro-Gly-Pro tripeptide upon Vegfa mRNA expression in different rat brain regions after common carotid artery occlusion. The animals were decapitated 30 min, 1, 2, 4, 8, 12, 24 h after the operation. It was shown that ischemia increases levels of Vegfa mRNA in the rat brain of animals (4 h after the occlusion--in the cerebellum, cerebral cortex and hippocampus, 8 h--in the cortex and hippocampus, and 24 h in the cortex). Semax treatment reduces Vegfa mRNA levels in the frontal cortex (4, 8 and 12 h after the occlusion) and hippocampus of ischemic rats (2 and 4 h). Effect of PGP on the Vegfa gene expression was almost negligible. Our results showed that semax prevents activating effect ofhypoxia on the Vegfa gene expression in early stages of global ischemia. Furthermore, increase in the level of mRNA Vegfa in the hippocampus (24 h after occlusion) perhaps reflects neuroprotective properties of this drug.

Diversity of Bradyrhizobium populations associated to soybean–maize rotations in Québec, Eastern Canada, and their potential to improve growth of both plant species

Bradyrhizobial populations associated with soybean–maize rotations have not been extensively studied, especially in Canada. In this work, we estimated the diversity of 255 bradyrhizobial strains isolated from soil, rhizosphere and nodules in farms under soybean or maize grown in rotation in Québec, Eastern Canada, and we characterized them for their ability to promote growth of both plants. The population was distributed into six IGS types. The major types IGS I and III included 98 and 70 strains respectively. About 50% of strains from soils of both plants and from soybean nodules were included in IGS I. Reference strains of Bradyrhizobium japonicum and inoculant products were included in IGS III and VI. Diversity indices were similar for both plants but were lower in soil and nodules than in rhizosphere of soybean. REP-PCR analysis was congruent with IGS typing, the major REP-clusters including a majority of strains within a same IGS type.With soybean, 25 strains allowed higher symbiotic effectiveness (shoot dry yield) than the commercial strain 532c and 5 strains (out of 8 tested) were more competitive for nodule occupancy. With maize, 20 strains showed a PGP effect increasing shoot dry weight by 10–20%. There was no link between the IGS type and symbiotic effectiveness or PGP effect, neither with siderophore or IAA production. Our results indicate that diverse bradyrhizobial strains may compete with inoculant strains, but this diversity can be exploited to select superior strains able to improve growth of both soybean and maize.

Cerebrospinal Fluid Can Be Used as a Surrogate to Assess Brain Exposures of Breast Cancer Resistance Protein and P-Glycoprotein Substrates

The objectives of the study were to characterize the selectivity of dantrolene to breast cancer resistance protein (Bcrp) and to evaluate whether cerebrospinal fluid (CSF) can be used as a surrogate to assess brain exposures of BCRP and P-glycoprotein (Pgp) substrates. The impact of Bcrp and Pgp on dantrolene exposures in brain and CSF was examined in Bcrp and Mdr1a/1b knockout mice and was further investigated in wild-type mice in the presence of the Bcrp inhibitor (3S,6S,12aS)-1,2,3,4,6,7,12,12a-octahydro-9-methoxy-6-(2-methylpropyl)-1,4-dioxopyrazino[1',2':1,6]pyrido[3,4-b]indole-3-propanoic acid 1,1-dimethylethyl ester (Ko143), the Pgp inhibitor 6-[(2S,4R,6E)-4-methyl-2-(methylamino)-3-oxo-6-octenoic acid]-7-l-valine-cyclosporine A (PSC833), and the dual inhibitor N-(4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]-phenyl)-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamide (GF120918). The effect of Bcrp and Pgp on digoxin exposures in brain and CSF was investigated in wild-type mice in the presence of the inhibitors. In vivo studies showed dantrolene exposures in brain and CSF, but not the blood, increased in Bcrp(-/-) and Mdr1a/1b(-/-)/Bcrp(-/-) mice, or in the presence of the Bcrp inhibitors Ko143 or GF120918. Inhibition of Pgp by GF120918 and PSC833 significantly increased digoxin exposures in brain, CSF, and blood to a lesser extent. Results from the present study demonstrated that inhibition of Bcrp and Pgp increased not only the exposures of dantrolene and digoxin in brain, but also the exposures in CSF. In addition, the change of exposures in CSF reflected the changes in brain. The present study strongly suggests that the dantrolene and digoxin exposures in CSF are primarily determined by the rapid transport from brain to CSF, and inhibition of Bcrp and Pgp exhibits little impact on using CSF as surrogates to assess brain exposures of Bcrp and Pgp substrates.

P-glycoprotein enhances radiation-induced apoptotic cell death through the regulation of miR-16 and Bcl-2 expressions in hepatocellular carcinoma cells

P-glycoprotein (Pgp), an efflux pump, was confirmed the first time to regulate the expressions of miR/gene in cells. Pgp is known to be associated with multidrug resistance. RHepG2 cells, the multidrug resistant subline of human hepatocellular carcinoma HepG2 cells, expressed higher levels of Pgp as well as miR-16, and lower level of Bcl-2 than the parental cells. In addition, RHepG2 cells were more radiation sensitive and showed more pronounced radiation-induced apoptotic cell death than the parental cells. Mechanistic analysis revealed that transfection with mdr1 specific antisense oligos suppressed radiation-induced apoptosis in HepG2 cells. On the other hand, ectopic mdr1 expression enhanced radiation-induced apoptosis in HepG2 cells, SK-HEP-1 cells, MiHa cells, and furthermore, induced miR-16 and suppressed its target gene Bcl-2 in HepG2 cells. Moreover, the enhancement effects of Pgp and miR-16 on radiation-induced apoptosis were counteracted by overexpression of Bcl-2. The Pgp effect on miR-16/Bcl-2 was suppressed by Pgp blocker verapamil indicating the importance of the efflux of Pgp substrates. The present study is the first to reveal the role of Pgp in regulation of miRNA/gene expressions. The findings may provide new perspective in understanding the biological function of Pgp.

Effect of Glyprolines PGP, GP, and PG on Homeostasis of Gastric Mucosa in Rats with Experimental Ethanol-Induced Gastric Ulcers

The decrease in the severity of erosions and ulcer lesions after preventive treatment with PGP or PG correlated with a decrease in the content of lipid peroxidation products to a control level. Activities of SOD and catalase also returned to control values. GP produced the weakest effect on pro- and antioxidant state of the gastric mucosa. We concluded that the pronounced preventive effect of PGP and PG on the development of ethanol-induced erosions and ulcer lesions is largely determined by their antioxidant properties. Glyprolines can be considered as a promising means for prevention and treatment of stomach and duodenal ulcers.

Abstract A148: Palomid 529, a dual mTor1/2 inhibitor, efficiently penetrates the blood-brain barrier and may be an attractive agent for treatment of glioblastoma

Abstract High-grade gliomas (WHO grade III anaplastic astrocytoma and grade IV glioblastoma multiforme) are the most common primary tumors in the central nervous system in adults and uniformly lethal. The current standard treatment (radiotherapy and temozolomide chemotherapy) has only a modest efficacy and better treatments are urgently needed. Activation of the EGFR/PI3K/Akt/mTor signaling cascade is a common event, especially in de novo glioblastoma (GBM) and, therefore, an attractive target for intervention by inhibitors. However, the blood-brain barrier (BBB) is an impediment for the delivery of many agents into the brain. Although GBM has the capacity to disrupt the blood-brain barrier, it is also a very invasive tumor with many tumor cells residing within areas of the brain where the BBB is still intact. Consequently it is important to consider the BBB penetration of novel candidate drugs for treatment of gliomas. We here present a pre-clinical pharmacokinetic study of Palomid 529, which is a novel small molecule inhibitor of mTor. This agent is attractive because it inhibits both the Torc1 and Torc2 complexes, thereby preventing upstream Akt activation through feedback loops. We have used in vitro transwell assays and found that Palomid 529 has negligible affinities for P-glycoprotein (Pgp) and Bcrp1, the two most dominant drug transporters that are expressed at the BBB. Subsequent studies in transporter knockout mouse models receiving i.v. P529 as a micronized drug formulation at a high dose (54 mg/kg) or low dose (5.4 mg/kg) confirmed these results and demonstrated that Palomid 529 penetrates the BBB efficiently with brain-to-plasma ratios exceeding 1. Only at the lowest dose level a minor effect of Pgp and Bcrp1 was observed. Based on these results we are now executing pre-clinical testing of Palomid 529 against orthotopic brain tumor models. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A148.

Blast cells from patients treated for secondary AML (sAML) show less P-glycoprotein (Pgp)-mediated efflux of amonafide compared to daunorubicin: Implications for therapy

13536 Background: Multidrug resistance (MDR) associated with Pgp overexpression in blasts is common in high-risk AML and is associated with poor outcomes. Erba et al (JCO 2007) reported a 42% complete remission (CR) rate in patients (pts) with sAML [prior MDS or treatment-related AML, (tAML)] (N = 88) treated with amonafide and std dose cytarabine. In laboratory studies of Pgp+ human leukemia cells, amonafide was neither a substrate nor an inhibitor of Pgp-mediated efflux, in contrast to daunorubicin (DNR). We sought to correlate the lack of Pgp effect with treatment outcome. Methods: AML blasts from 15 pts from the Phase 2 trial cited above were retrospectively assessed for Pgp expression and function as well as amonafide and DNR uptake and retention in the presence and absence of the Pgp inhibitor cyclosporin A. Pts: median age, 62 yrs (range 51–87); 7 with prior MDS; 8 had tAML; 10 with unfavorable cytogenetics. Pgp-mediated efflux was assessed by comparing uptake of the Pgp substrate DiOC2(3) in the presence and absence of the Pgp inhibitor PSC-833. Pgp- mediated transport (effluxapp) was calculated as differential uptake and retention of amonafide and DNR with (a) and without (b) PSC-833, normalized to apparent influx, using the formula [(a-b)/a]×100, reported as the mean±s.e.m. Results: The 15 sAML samples showed significantly less effluxapp of amonafide (5.2%±3.2) than of DNR (16%±2.1; p=0.0083). The unfavorable cytogenetic subset showed much less effluxapp of amonafide (0.13%±3.7) compared to DNR (16%±2.1; p=0.0015). CR pts also showed less effluxapp of amonafide (4.0%±6.7) than of DNR (21%±2.9; p=0.035). Conclusions: The relative lack of Pgp-mediated efflux of amonafide, compared to DNR, from sAML blasts provides a rationale for its observed clinical efficacy in the Phase 2 trial. Prospective assessment of these MDR parameters is underway in a randomized Phase 3 clinical trial in sAML comparing amonafide to DNR in combination with std dose cytarabine for remission induction. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Xanthus Pharmaceuticals Xanthus Pharmaceuticals Xanthus Pharmaceuticals

Human intestinal P‐glycoprotein activity estimated by the model substrate digoxin

Objective. P‐glycoprotein (Pgp) plays a part in the intestinal uptake of xenobiotics and has been associated with susceptibility to ulcerative colitis. The aim of this study was to examine Pgp activity in relation to age, gender, medical treatment (rifampicin or ketoconazole) and the multidrug resistance (MDR1) gene single nucleotide polymorphisms (SNPs) G2677T and C3435T using the model drug digoxin. Material and methods. Pgp activity was estimated from the pharmacokinetics of orally administered digoxin in blood samples from 32 healthy subjects. MDR1 gene expression in duodenal biopsies was monitored by real‐time quantitative RT‐PCR (RQ‐PCR) and Western blot analyses. MDR1 SNPs were determined by PCR‐restriction fragment length polymorphism (PCR‐RFLP). The effect of medical treatment was tested by open, randomized, cross‐over treatment with rifampicin and ketoconazole. Results. Rifampicin treatment resulted in increased Pgp activity, duodenal MDR1 mRNA expression and Pgp detection compared with that in the control group (p<0.05 for all), Pgp activity being associated with duodenal MDR1 mRNA level (p<0.05). Individuals homozygous for the 3435 wild‐type allele (CC) showed higher Pgp activity (p<0.05), whereas SNP 2677 apparently did not affect Pgp activity. No variation in Pgp in relation to age or gender was found. Conclusions. Our data confirm that rifampicin increases Pgp activity, by increasing MDR1 mRNA and Pgp levels. Moreover, we found that the wild‐type allele of the synonymous polymorphism of MDR1 position 3435 confers a higher Pgp activity. These data support other findings suggesting an effect of Pgp on treatment response and disease susceptibility.