Dose-dependent intracellular accumulation of test ERAs in sandwich-cultured human hepatocytes.

<p>Ambrisentan displayed the lowest intracellular accumulation followed by bosentan, sitaxsentan, and macitentan. Data are presented as mean (±SD) micromolar (µM) concentration; n = 3 donors; *P<0.05 vs. corresponding intracellular accumulation value for ambrisentan at the same test concentration.</p

Uptake of bosentan and macitentan into human hepatocytes.

<p>ERAs were evaluated either in the absence or presence of the transporter inhibitors rifampicin (40 µM) and cyclosporin A (5 µM). Data presented as mean (±SD) pmol/million cells; n = 4 donors; *P<0.05 for comparisons indicated.</p

Effect of Ambrisentan, Bosentan, Sitaxsentan, and Macitentan on Hepatic Uptake and Efflux Transporters.

a<p>Data presented as mean ± standard deviation for 3 independent studies performed in duplicate;</p>b<p>Data presented for a single experiment preformed in duplicate;</p>c<p>Data previously reported <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087548#pone.0087548-Ray1" target="_blank">[35]</a>. Ambrisentan, bosentan, and macitentan were tested in concentrations ranging from 0.14–100 µM.</p><p>ND = not determined.</p

d₈-Taurocholate (d₈-TCA) total (A) and cellular (B) accumulation in sandwich-cultured human hepatocytes exposed to ambrisentan, bosentan and macitentan.

<p>Bosentan and macitentan treatment resulted in a dose-dependent reduction in total accumulation of d₈-TCA. Ambrisentan, bosentan and macitentan treatment each resulted in a dose-dependent reduction in cellular accumulation of d₈-TCA. Data presented as mean (±SD) expressed as percent of control treated; n = 3 donors; *P<0.05 bosentan vs. control; # P<0.05 macitentan vs. control.</p

Metformin Is a Substrate and Inhibitor of the Human Thiamine Transporter, THTR‑2 (SLC19A3)

The biguanide metformin is widely used as first-line therapy for the treatment of type 2 diabetes. Predominately a cation at physiological pH’s, metformin is transported by membrane transporters, which play major roles in its absorption and disposition. Recently, our laboratory demonstrated that organic cation transporter 1, OCT1, the major hepatic uptake transporter for metformin, was also the primary hepatic uptake transporter for thiamine, vitamin B1. In this study, we tested the reverse, i.e., that metformin is a substrate of thiamine transporters (THTR-1, SLC19A2, and THTR-2, SLC19A3). Our study demonstrated that human THTR-2 (hTHTR-2), SLC19A3, which is highly expressed in the small intestine, but not hTHTR-1, transports metformin (<i>K</i>_m = 1.15 ± 0.2 mM) and other cationic compounds (MPP⁺ and famotidine). The uptake mechanism for hTHTR-2 was pH and electrochemical gradient sensitive. Furthermore, metformin as well as other drugs including phenformin, chloroquine, verapamil, famotidine, and amprolium inhibited hTHTR-2 mediated uptake of both thiamine and metformin. Species differences in the substrate specificity of THTR-2 between human and mouse orthologues were observed. Taken together, our data suggest that hTHTR-2 may play a role in the intestinal absorption and tissue distribution of metformin and other organic cations and that the transporter may be a target for drug–drug and drug–nutrient interactions

Atropisomerism by Design: Discovery of a Selective and Stable Phosphoinositide 3‑Kinase (PI3K) β Inhibitor

Atropisomerism is a type of axial chirality in which enantiomers or diastereoisomers arise due to hindered rotation around a bond axis. In this manuscript, we report a case in which torsional scan studies guided the thoughtful creation of a restricted axis of rotation between two heteroaromatic systems of a phosphoinositide 3-kinase (PI3K) β inhibitor, generating a pair of atropisomeric compounds with significantly different pharmacological and pharmacokinetic profiles. Emblematic of these differences, the metabolism of inactive (<i>M</i>)-<b>28</b> is primarily due to the cytosolic enzyme aldehyde oxidase, while active (<i>P</i>)-<b>28</b> has lower affinity for aldehyde oxidase, resulting in substantially better metabolic stability. Additionally, we report torsional scan and experimental studies used to determine the barriers of rotation of this novel PI3Kβ inhibitor

Atropisomerism by Design: Discovery of a Selective and Stable Phosphoinositide 3‑Kinase (PI3K) β Inhibitor

Atropisomerism is a type of axial chirality in which enantiomers or diastereoisomers arise due to hindered rotation around a bond axis. In this manuscript, we report a case in which torsional scan studies guided the thoughtful creation of a restricted axis of rotation between two heteroaromatic systems of a phosphoinositide 3-kinase (PI3K) β inhibitor, generating a pair of atropisomeric compounds with significantly different pharmacological and pharmacokinetic profiles. Emblematic of these differences, the metabolism of inactive (<i>M</i>)-<b>28</b> is primarily due to the cytosolic enzyme aldehyde oxidase, while active (<i>P</i>)-<b>28</b> has lower affinity for aldehyde oxidase, resulting in substantially better metabolic stability. Additionally, we report torsional scan and experimental studies used to determine the barriers of rotation of this novel PI3Kβ inhibitor

Atropisomerism by Design: Discovery of a Selective and Stable Phosphoinositide 3‑Kinase (PI3K) β Inhibitor

Atropisomerism is a type of axial chirality in which enantiomers or diastereoisomers arise due to hindered rotation around a bond axis. In this manuscript, we report a case in which torsional scan studies guided the thoughtful creation of a restricted axis of rotation between two heteroaromatic systems of a phosphoinositide 3-kinase (PI3K) β inhibitor, generating a pair of atropisomeric compounds with significantly different pharmacological and pharmacokinetic profiles. Emblematic of these differences, the metabolism of inactive (<i>M</i>)-<b>28</b> is primarily due to the cytosolic enzyme aldehyde oxidase, while active (<i>P</i>)-<b>28</b> has lower affinity for aldehyde oxidase, resulting in substantially better metabolic stability. Additionally, we report torsional scan and experimental studies used to determine the barriers of rotation of this novel PI3Kβ inhibitor

Discovery of a Phosphoinositide 3‑Kinase (PI3K) β/δ Inhibitor for the Treatment of Phosphatase and Tensin Homolog (PTEN) Deficient Tumors: Building PI3Kβ Potency in a PI3Kδ-Selective Template by Targeting Nonconserved Asp856

Phosphoinositide 3-kinase (PI3K) β signaling is required to sustain cancer cell growth in which the tumor suppressor phosphatase and tensin homolog (PTEN) has been deactivated. This manuscript describes the discovery, optimization, and in vivo evaluation of a novel series of PI3Kβ/δ inhibitors in which PI3Kβ potency was built in a PI3Kδ-selective template. This work led to the discovery of a highly selective PI3Kβ/δ inhibitor displaying excellent pharmacokinetic profile and efficacy in a human PTEN-deficient LNCaP prostate carcinoma xenograft tumor model

Discovery of Orally Efficacious Phosphoinositide 3‑Kinase δ Inhibitors with Improved Metabolic Stability

Aberrant signaling of phosphoinositide 3-kinase δ (PI3Kδ) has been implicated in numerous pathologies including hematological malignancies and rheumatoid arthritis. Described in this manuscript are the discovery, optimization, and in vivo evaluation of a novel series of pyridine-containing PI3Kδ inhibitors. This work led to the discovery of <b>35</b>, a highly selective inhibitor of PI3Kδ which displays an excellent pharmacokinetic profile and is efficacious in a rodent model of rheumatoid arthritis