Metabolism and disposition of the SGLT2 inhibitor bexagliflozin in rats, monkeys and humans.

Bexagliflozin is a C-aryl glucoside inhibitor of human sodium-glucose linked transporter 2 (SGLT2) that undergoes oxidation and glucuronidation to form six principal metabolites in humans.In vitro metabolism by human liver microsomes and recombinant enzymes is primarily mediated by CYP3A4 and UGT1A9. Three major oxidation products and three major glucuronides have been identified in vivo. Metabolism by rats is mostly by oxidation whereas metabolism by monkeys and humans is mostly by glucuronidation. Metabolism by monkeys closely resembles metabolism by humans and all metabolites found in humans are also found in monkeys. A greater diversity of metabolites has been identified among human in vivo specimens than among in vitro reaction products.Following oral dosing of humans with 14C-bexagliflozin, the 3'-O-glucuronide contributed 32% of the parent AUC and all other metabolites contributed <10%. Of the 91.6% of input radioactivity recovered, 51.1% was in faeces, predominantly as bexagliflozin, and 40.5% was in urine, largely as the 3'-O-glucuronide. Unidentified metabolites contributed 0.27% of the input radiolabel.A quantitative accounting for the metabolism and disposition of bexagliflozin in vivo has been developed.

Positive Allosteric Modulation of A2AR Alters Immune Cell Responses and Ameliorates Psoriasis-Like Dermatitis in Mice.

Psoriasis is an immune cell‒mediated inflammatory disease of the skin with a mixed T helper type 1/T helper type17 cytokine environment combined with an innate immune response engaging toll-like receptors. Inflammatory diseases are characterized by dysregulated immune cell responses and elevated levels of adenosine at disease sites. Adenosine, acting through the A2AR, regulates inflammation, immune response, T-cell homeostasis, and tissue repair. We have identified a unique means to enhance A2AR function using a positive allosteric modulator. We show that oral administration of the A2AR-positive allosteric modulator AEA061 reduced ear swelling, skin thickness, erythema, scale formation, and inflammatory cytokine expression in A2Ar+/+ but not in A2Ar-/- mice with imiquimod-induced psoriasis-like dermatitis. Similar clinical and mRNA improvements were observed with topical administration. AEA061 also reduced clinical scores and cytokine expression in a mouse model of IL-23‒induced psoriasis-like dermatitis. In addition, AEA061 attenuated imiquimod-induced expression of IFN-α in plasmacytoid dendritic cells in vivo and IL-23 and IL-36α in conventional dendritic cells. TCR-mediated IL-17 expression in γδT cells in vivo and IL-17 production by CD4+ T cells enriched for γδT cells in vitro were also inhibited. Thus, the enhancement of A2AR responsiveness to the endogenous agonist adenosine through positive allosteric modulation is sufficient to enhance intrinsic homeostatic mechanisms attenuating disease progression.

EGT1442, a potent and selective SGLT2 inhibitor, attenuates blood glucose and HbA(1c) levels in db/db mice and prolongs the survival of stroke-prone rats.

Sodium glucose co-transporter 2 (SGLT2) is a renal type III integral membrane protein that co-transports sodium and glucose from filtrate to epithelium in the proximal tubule. Human subjects with homozygous or compound heterozygous mutations in SLC5A2 exhibit glucosuria without hypoglycemia or other obvious morbidity, suggesting that blockade of SGLT2 has the potential to promote normalization of blood glucose without hypoglycemia in the setting of type 2 diabetes. This report presents the in vitro and in vivo pharmacological activities of EGT1442, a recently discovered SGLT2 inhibitor in the C-aryl glucoside class. The inhibitory effects of EGT1442 for human SGLT1 and SGLT2 were evaluated in an AMG uptake assay and the in vivo efficacy of treatment with EGT1442 was investigated in rats and dogs after a single dose and in db/db mice after chronic administration. The effect of EGT1442 on median survival of SHRSP rats was also evaluated. The IC(50) values for EGT1442 against human SGLT1 and SGLT2 are 5.6µM and 2nM, respectively. In normal rats and dogs a saturable urinary glucose excretion was produced with an ED(50) of 0.38 and 0.09mg/kg, respectively. Following chronic administration to db/db mice, EGT1442 dose-dependently reduced HbA(1c) and blood glucose concentration without affecting body mass or insulin level. Additionally, EGT1442 significantly prolonged the median survival of SHRSP rats. EGT1442 showed favorable properties both in vitro and in vivo and could be beneficial to the management of type 2 diabetic patients.

C-aryl glucosides substituted at the 4'-position as potent and selective renal sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors for the treatment of type 2 diabetes.

A series of C-aryl glucosides with various substituents at the 4'-position of the distal aryl ring have been synthesized and evaluated for inhibition of hSGLT1 and hSGLT2. Introduction of alkyl or alkoxy substituents at the 4'-position was found to improve SGLT2 potency, whereas introduction of a hydrophilic group at this position was deleterious. Compounds with alkoxy-, cycloalkoxy- or cycloalkenyloxy-ethoxy scaffolds exhibited good inhibitory activity and high selectivity toward SGLT2. Selected compounds were investigated for in vivo efficacy.

ortho-Substituted C-aryl glucosides as highly potent and selective renal sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors.

A series of 2-substituted C-aryl glucosides have been synthesized and evaluated for inhibition of hSGLT1 and hSGLT2. Introduction of an appropriate ortho substituent at the proximal phenyl ring adjacent to the glycosidic bond was found to improve SGLT2 inhibitory activity and dramatically increase selectivity for hSGLT2 over hSGLT1. Selected compounds were investigated for in vivo efficacy.

O-Spiro C-aryl glucosides as novel sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors.

Two series of O-spiro C-aryl glucosides were synthesized and tested for inhibition of hSGLT1 and hSGLT2. 6'-O-Spiro C-aryl glucosides exhibited potent in vitro hSGLT2 inhibitory activity but 2'-O-spiro C-aryl glucosides showed no in vitro hSGLT2 inhibitory activity at a screening concentration of 1microM.

Exploration of O-spiroketal C-arylglucosides as novel and selective renal sodium-dependent glucose co-transporter 2 (SGLT2) inhibitors.

A series of novel O-spiroketal C-arylglucosides have been prepared and evaluated in cell-based functional assays for activity against human sodium-dependent glucose co-transporters 1 and 2 (SGLT1 and 2). The core spiro[isobenzofuran-1,2'-pyran] structure proved to be an effective scaffold for diversification and a number of compounds with single digit nanomolar potency and high selectivity have been synthesized. Compound 5a promoted glucosuria when administered in vivo in rats and produced a significant blood glucose reduction effect.

Enhancement of inosine-mediated A2AR signaling through positive allosteric modulation.

Inosine is an endogenous nucleoside that is produced by metabolic deamination of adenosine. Inosine is metabolically more stable (half-life 15h) than adenosine (half-life <10s). Inosine exerts anti-inflammatory and immunomodulatory effects similar to those observed with adenosine. These effects are mediated in part through the adenosine A2A receptor (A2AR). Relative to adenosine inosine exhibits a lower affinity towards the A2AR. Therefore, it is generally believed that inosine is incapable of activating the A2AR through direct engagement, but indirectly activates the A2AR upon metabolic conversion to higher affinity adenosine. A handful of studies, however, have provided evidence for direct inosine engagement at the A2AR leading to activation of downstream signaling events and inhibition of cytokine production. Here, we demonstrate that under conditions devoid of adenosine, inosine as well as an analog of inosine 6-S-[(4-Nitrophenyl)methyl]-6-thioinosine selectively and dose-dependently activated A2AR-mediated cAMP production and ERK1/2 phosphorylation in CHO cells stably expressing the human A2AR. Inosine also inhibited LPS-stimulated TNF-α, CCL3 and CCL4 production by splenic monocytes in an A2AR-dependent manner. In addition, we demonstrate that a positive allosteric modulator (PAM) of the A2AR enhanced inosine-mediated cAMP production, ERK1/2 phosphorylation and inhibition of pro-inflammatory cytokine and chemokine production. The cumulative effects of allosteric enhancement of adenosine-mediated and inosine-mediated A2AR activation may be the basis for the sustained anti-inflammatory and immunomodulatory effects observed in vivo and thereby provide insights into potential therapeutic interventions for inflammation- and immune-mediated diseases.

Comparison of the Human A2A Adenosine Receptor Recognition by Adenosine and Inosine: New Insight from Supervised Molecular Dynamics Simulations.

Adenosine deaminase converts adenosine into inosine. In contrast to adenosine, relatively little attention has been paid to the physiological roles of inosine. Nevertheless, recent studies have demonstrated that inosine has neuroprotective, cardioprotective, immunomodulatory, and antidepressive effects. Inosine was recently shown to be a less potent agonist than adenosine at the A2A adenosine receptor. To better depict the differences in the mechanisms of receptor recognition between adenosine and inosine, we carried out supervised molecular dynamics (SuMD) simulations, and the results are analyzed herein.

The adenosine metabolite inosine is a functional agonist of the adenosine A2A receptor with a unique signaling bias.

Inosine is an endogenous purine nucleoside that is produced by catabolism of adenosine. Adenosine has a short half-life (approximately 10s) and is rapidly deaminated to inosine, a stable metabolite with a half-life of approximately 15h. Resembling adenosine, inosine acting through adenosine receptors (ARs) exerts a wide range of anti-inflammatory and immunomodulatory effects in vivo. The immunomodulatory effects of inosine in vivo, at least in part, are mediated via the adenosine A2A receptor (A2AR), an observation that cannot be explained fully by in vitro pharmacological characterization of inosine at the A2AR. It is unclear whether the in vivo effects of inosine are due to inosine or a metabolite of inosine engaging the A2AR. Here, utilizing a combination of label-free, cell-based, and membrane-based functional assays in conjunction with an equilibrium agonist-binding assay we provide evidence for inosine engagement at the A2AR and subsequent activation of downstream signaling events. Inosine-mediated A2AR activation leads to cAMP production with an EC50 of 300.7µM and to extracellular signal-regulated kinase-1 and -2 (ERK1/2) phosphorylation with an EC50 of 89.38µM. Our data demonstrate that inosine produces ERK1/2-biased signaling whereas adenosine produces cAMP-biased signaling at the A2AR, highlighting pharmacological differences between these two agonists. Given the in vivo stability of inosine, our data suggest an additional, previously unrecognized, mechanism that utilizes inosine to functionally amplify and prolong A2AR activation in vivo.

Positive allosteric modulation of the adenosine A2a receptor attenuates inflammation.

BACKGROUND: Adenosine is produced at high levels at inflamed sites as a by-product of cellular activation and breakdown. Adenosine mediates its anti-inflammatory activity primarily through the adenosine A2a receptor (A2aR), a member of the G-protein coupled receptors. A2aR agonists have demonstrated anti-inflammatory efficacy, however, their therapeutic utility is hindered by a lack of adenosine receptor subtype selectivity upon systemic exposure. We sought to harness the anti-inflammatory effects of adenosine by enhancing the responsiveness of A2aR to endogenously produced adenosine through allosteric modulation. We have identified a family of positive allosteric modulators (PAMs) of the A2aR. Using one member of this PAM family, AEA061, we demonstrate that A2aRs are amenable to allosteric enhancement and such enhancement produces increased A2aR signaling and diminished inflammation in vivo. METHODS: A2aR activity was evaluated using a cell-based cAMP assay. Binding affinity of A2aR was determined using [(3)H]CGS 21680. A2aR-mediated G-protein activation was quantified using [(35)S]GTP-γS. The effect of AEA061 on cytokine production was evaluated using primary monocytes and splenocytes. The anti-inflammatory effect of AEA061 was evaluated in the LPS-induced mouse model of inflammation. RESULTS: AEA061 had no detectable intrinsic agonist activity towards either rat or human A2aRs. AEA061 enhanced the efficacy of adenosine to rat and human A2aRs by 11.5 and 2.8 fold respectively. AEA061 also enhanced the maximal response by 4.2 and 2.1 fold for the rat and the human A2aR respectively. AEA061 potentiated agonist-mediated Gα activation by 3.7 fold. Additionally, AEA061 enhanced both the affinity as well as the Bmax at the human A2aR by 1.8 and 3 fold respectively. Consistent with the anti-inflammatory role of the A2aR, allosteric enhancement with AEA061 inhibited the production of TNF-α, MIP-1α, MIP-1ß, MIP-2, IL-1α, KC and RANTES by LPS-stimulated macrophages and/or splenocytes. Moreover, AEA061 reduced circulating plasma TNF-α and MCP-1 levels and increased plasma IL-10 in endotoxemic A2aR intact, but not in A2aR deficient, mice. CONCLUSIONS: AEA061 increases affinity and Bmax of A2aR to adenosine, thereby increasing adenosine potency and efficacy, which translates to enhanced A2aR responsiveness. Since the A2aR negatively regulates inflammation, PAMs of the receptor offer a novel means of modulating inflammatory processes.

Design, synthesis, and biological evaluation of deuterated C-aryl glycoside as a potent and long-acting renal sodium-dependent glucose cotransporter 2 inhibitor for the treatment of type 2 diabetes.

SGLT2 inhibitors deuterated at sites susceptible to oxidative metabolism were found to have a slightly longer tmax and half-life (t1/2), dose-dependent increase in urinary glucose excretion (UGE) in rats, and slightly superior effects on UGE in dogs while retaining similar in vitro inhibitory activities against hSGLT2. In particular, deuterated compound 41 has the potential to be a robust long-acting antidiabetic agent.

Interaction of two actin-binding proteins, synaptopodin and alpha-actinin-4, with the tight junction protein MAGI-1.

In an attempt to find podocyte-expressed proteins that may interact with the tight junction protein MAGI-1, we screened a glomerulus-enriched cDNA library with a probe consisting of both WW domains of MAGI-1. One of the isolated clones contained two WW domain-binding motifs and was identified as a portion of the actin-bundling protein synaptopodin. In vitro binding assays confirmed this interaction between MAGI-1 and synaptopodin and identified the second WW domain of MAGI-1 to be responsible for the interaction. MAGI-1 and synaptopodin can also interact in vivo, as they can be immunoprecipitated together from HEK293 cell lysates. Another actin-bundling protein that is found in glomerular podocytes and shown to be mutated in an inheritable form of glomerulosclerosis is alpha-actinin-4. We show that alpha-actinin-4 is also capable of binding to MAGI-1 in in vitro binding assays and that this interaction is mediated by the fifth PDZ domain of MAGI-1 binding to the C terminus of alpha-actinin-4. Exogenously expressed synaptopodin and alpha-actinin-4 were found to colocalize along with endogenous MAGI-1 at the tight junction of Madin-Darby canine kidney cells. The interaction and colocalization of MAGI-1 with two actin-bundling proteins suggest that MAGI-1 may play a role in actin cytoskeleton dynamics within polarized epithelial cells.