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The pandemic of COVID-2019 has urged the development of antiviral agents against its causative pathogen SARS-CoV-2. The main protease (Mpro), a cysteine protease essential for viral replication, is a promising protein target. Here we report an irreversible SARS-CoV-2 Mpro inhibitor possessing chlorofluoroacetamide (CFA) as the warhead for covalent modification of Mpro. Ugi multi-component reaction employing chlorofluoroacetic acid allowed rapid generation of CFA derivatives, of which diastereomers displayed significantly different inhibitory activity against Mpro. We established a practical protocol for the optical resolution of chlorofluoroacetic acid, which enable the isolation of the stereoisomers of the best CFA compound. Kinetic analysis revealed that (R)-CFA is crucial for both binding affinity and the rate of irreversible inactivation of Mpro. Our findings highlight the prominent influence of the CFA chirality on the covalent modification of cysteine, and provide the basis for improving the potency and selectivity in the development of novel CFA-based covalent inhibitors.

Phosphodiesterase (PDE) 10A is a dual hydrolase of cAMP and cGMP and highly expressed in striatal medium spiny neurons. Inhibition of PDE10A modulates the activity of medium spiny neurons (MSN) via the regulation of cAMP and cGMP. Signal control of MSN is considered associated with psychotic symptoms. Therefore PDE10A inhibitor is expected as a therapeutic method for psychosis disease such as schizophrenia. Avanafil (1) is a PDE5 inhibitor (treatment for erectile dysfunction) discovered by our company. We paid attention to the homology of PDE10A and PDE5 and took advantage of PDE5 inhibitor library to discover PDE10A inhibitors, and found a series of compounds that exhibit higher potency for PDE10A than PDE5. We transformed the afforded derivatives, which had weak inhibitory activity against PDE10A, and discovered stilbene as a PDE10A inhibitor. Brain penetration of this compound was improved by further conversion of N-containing heterocycles and their substituents. The afforded dimethylaminopyrimidine was effective for rat conditioned avoidance response (CAR) test; however, it did not exhibit good brain penetration. We performed in-depth optimization focusing on substituents of the quinoxaline ring, and produced 3-methyl-7-fluoro quinoxaline. This compound was the most effective in rat CAR test due to its strong PDE10A inhibitory activity and good pharmacokinetics.

Phosphodiesterase (PDE) 10A is a dual hydrolase of cAMP and cGMP and highly expressed in striatal medium spiny neurons. Inhibition of PDE10A modulates the activity of medium spiny neurons (MSN) via the regulation of cAMP and cGMP. Signal control of MSN is considered associated with psychotic symptoms. Therefore PDE10A inhibitor is expected as a therapeutic method for psychosis disease such as schizophrenia. Avanafil (1) is a PDE5 inhibitor (treatment for erectile dysfunction) discovered by our company. We paid attention to the homology of PDE10A and PDE5 and took advantage of PDE5 inhibitor library to discover PDE10A inhibitors, and found a series of compounds that exhibit higher potency for PDE10A than PDE5. We transformed the afforded derivatives, which had weak inhibitory activity against PDE10A, and discovered stilbene as a PDE10A inhibitor. Brain penetration of this compound was improved by further conversion of N-containing heterocycles and their substituents. The afforded dimethylaminopyrimidine was effective for rat conditioned avoidance response (CAR) test; however, it did not exhibit good brain penetration. We performed in-depth optimization focusing on substituents of the quinoxaline ring, and produced 3-methyl-7-fluoro quinoxaline. This compound was the most effective in rat CAR test due to its strong PDE10A inhibitory activity and good pharmacokinetics.

The synthesis and structure-activity relationship (SAR) of thiophene-C-glucosides have been explored, and the human sodium-dependent glucose cotransporter 2 (hSGLT2) inhibitory activities and rat urinary glucose excretion (UGE) effects of 3a-f were evaluated. As a result, they showed good hSGLT2 inhibitory activities and rat UGE effects. In particular, the chlorothiophene derivative 3f showed remarkable inhibitory activity against hSGLT2.

UNLABELLED: Four novel phosphodiesterase 10A (PDE10A) PET tracers have been synthesized, characterized in preclinical studies, and compared with the previously reported (11)C-MP-10.METHODS: On the basis of in vitro data, IMA102, IMA104, IMA107, and IMA106 were identified as potential PDE10A radioligand candidates and labeled with either (11)C via N-methylation or with (18)F through an SN2 reaction, in the case of IMA102. These candidates were compared with (11)C-MP-10 in pilot in vivo studies in the pig brain. On the basis of these data, (11)C-IMA106 and (11)C-IMA107 were taken into further evaluation and comparison with (11)C-MP-10 in the primate brain. Finally, the most promising radioligand candidate was progressed into human evaluation.RESULTS: All 5 tracers were produced with good radiochemical yield and specific activity. All candidates readily entered the brain and demonstrated a heterogeneous distribution consistent with the known expression of PDE10A. Baseline PET studies in the pig and baboon showed that (11)C-IMA107 and (11)C-MP-10 displayed the most favorable tissue kinetics and imaging properties. The administration of selective PDE10A inhibitors reduced the binding of (11)C-IMA107 and (11)C-MP-10 in the PDE10A-rich brain regions, in a dose-dependent manner. In the nonhuman primate brain, the tissue kinetics of (11)C-IMA107 and (11)C-MP-10 were well described by a 2-tissue-compartment model, allowing robust estimates of the regional total volume of distribution. Blockade with unlabeled MP-10 confirmed the suitability of the cerebellum as a reference tissue and enabled the estimation of regional binding potential as the outcome measure of specific binding.CONCLUSION: (11)C-IMA107 was identified as the ligand with the highest binding potential while still possessing reversible kinetics. The first human administration of (11)C-IMA107 has demonstrated the expected regional distribution and suitably fast kinetics, indicating that (11)C-IMA107 will be a useful tool for the investigation of PDE10A status in the living human brain.

The synthesis and structure-activity relationship (SAR) of thiophene-C-glucosides have been explored, and the human sodium-dependent glucose cotransporter 2 (hSGLT2) inhibitory activities and rat urinary glucose excretion (UGE) effects of 3a-f were evaluated. As a result, they showed good hSGLT2 inhibitory activities and rat UGE effects. In particular, the chlorothiophene derivative 3f showed remarkable inhibitory activity against hSGLT2.

Metalated O-silyl cyanohydrins of beta-silyl-alpha,beta-epoxyaldehyde have been found to serve as functionalized homoenolate equivalents by a tandem sequence involving base-promoted ring opening of the epoxide, Brook rearrangement, and alkylation of the resulting allylic anion. On the basis of mechanistic studies involving competitive experiments using the diastereomeric cyanohydrins, we propose a reaction pathway involving a silicate intermediate 36 formed by a concerted process via an anti-opening of the epoxide followed by the formation of an O-Si bond.

Three types of membranes of poly (γ-methyl D-glutamate) (PMDG), membrane A, B and C, were cast from 2% PMDG-ethylene dichloride solution under the different conditions. The membrane A was obtained by vacuum drying of the solution at 25°C for about 2 hrs. The membrane B and C were prepared by air-drying of the solution at 25°C for 3 days and 30 days, respectively. Sorption behaviors of these membranes could be described well by a dual sorption model which have been used effectively for gas-glassy polymer systems. The temperature dependence of Henry's law sorption parameter, kD, of membrane B and C had an inflection point at the second order transition temperature of the side chain. On the other hand, kD of membrane A linearly increased with increasing temperature. The Langmuir capacity term, C′H, of membrane A was considerably larger than those of B and C. The permeation behavior of membrane A involved the convectional flow, i.e., the permeability coefficient of CO2 through membrane A linearly increased with increasing upstream pressure. On the other hand, the permeation behaviors of membrane B and C could be interpreted by the dual mobility model. As a result, separate diffusion coefficients of CO2 for Henry's law and Langmuir modes, DD and DH, were estimated. It was found that the diffusivity for the Langmuir mode gas in the membranes was relatively high, DH/DD being almost equal to unity. All of these results were ascribed to the difference of the packing state of the α-helix chains in these membranes, which was caused by the different membrane preparation.