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Pharmaceuticals (Basel) ; 15(6)2022 May 27.
Article in English | MEDLINE | ID: covidwho-1869735


MPI8, a peptidyl aldehyde, is a potent antiviral agent against coronavirus. Due to unique tri-peptide bonds and the formyl functional group, the bioassay of MPI8 in plasma was challenged by a strong interference from water MPI8. Using QTOF LC-MS/MS, we identified MPI8•H2O as the major interference form that co-existed with MPI8 in aqueous and biological media. To avoid the resolution of MPI8 and MPI8•H2O observed on reverse phase columns, we found that a Kinetex hydrophilic interaction liquid chromatography (HILIC) column provided co-elution of both MPI8 and MPI8•H2O with a good single chromatographic peak and column retention of MPI8 which is suitable for quantification. Thus, a sensitive, specific, and reproducible LC-MS/MS method for the quantification of MPI8 in rat plasma was developed and validated using a triple QUAD LC-MS/MS. The chromatographic separation was achieved on a Kinetex HILIC column with a flow rate of 0.4 mL/min under gradient elution. The calibration curves were linear (r2 > 0.99) over MPI8 concentrations from 0.5-500 ng/mL. The accuracy and precision are within acceptable guidance levels. The mean matrix effect and recovery were 139% and 73%, respectively. No significant degradation of MPI8 occurred under the experimental conditions. The method was successfully applied to a pharmacokinetic study of MPI8 after administration of MPI8 sulfonate in rats.

Dalton Trans ; 50(35): 12226-12233, 2021 Sep 14.
Article in English | MEDLINE | ID: covidwho-1358359


Numerous organic molecules are known to inhibit the main protease of SARS-CoV-2, (SC2Mpro), a key component in viral replication of the 2019 novel coronavirus. We explore the hypothesis that zinc ions, long used as a medicinal supplement and known to support immune function, bind to the SC2Mpro enzyme in combination with lipophilic tropolone and thiotropolone ligands, L, block substrate docking, and inhibit function. This study combines synthetic inorganic chemistry, in vitro protease activity assays, and computational modeling. While the ligands themselves have half maximal inhibition concentrations, IC50, for SC2Mpro in the 8-34 µM range, the IC50 values are ca. 100 nM for Zn(NO3)2 which are further enhanced in Zn-L combinations (59-97 nM). Isolation of the Zn(L)2 binary complexes and characterization of their ability to undergo ligand displacement is the basis for computational modeling of the chemical features of the enzyme inhibition. Blind docking onto the SC2Mpro enzyme surface using a modified Autodock4 protocol found preferential binding into the active site pocket. Such Zn-L combinations orient so as to permit dative bonding of Zn(L)+ to basic active site residues.

COVID-19/drug therapy , Coronavirus 3C Proteases/antagonists & inhibitors , Protease Inhibitors/pharmacology , SARS-CoV-2/drug effects , Tropolone/pharmacology , Zinc/pharmacology , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , COVID-19/virology , Catalytic Domain/drug effects , Coronavirus 3C Proteases/chemistry , Coronavirus 3C Proteases/metabolism , Humans , Ligands , Models, Molecular , Molecular Docking Simulation , Protease Inhibitors/chemistry , SARS-CoV-2/enzymology , Tropolone/analogs & derivatives , Zinc/chemistry
J Med Chem ; 64(15): 11267-11287, 2021 08 12.
Article in English | MEDLINE | ID: covidwho-1319012


Cysteine proteases comprise an important class of drug targets, especially for infectious diseases such as Chagas disease (cruzain) and COVID-19 (3CL protease, cathepsin L). Peptide aldehydes have proven to be potent inhibitors for all of these proteases. However, the intrinsic, high electrophilicity of the aldehyde group is associated with safety concerns and metabolic instability, limiting the use of aldehyde inhibitors as drugs. We have developed a novel class of self-masked aldehyde inhibitors (SMAIs) for cruzain, the major cysteine protease of the causative agent of Chagas disease-Trypanosoma cruzi. These SMAIs exerted potent, reversible inhibition of cruzain (Ki* = 18-350 nM) while apparently protecting the free aldehyde in cell-based assays. We synthesized prodrugs of the SMAIs that could potentially improve their pharmacokinetic properties. We also elucidated the kinetic and chemical mechanism of SMAIs and applied this strategy to the design of anti-SARS-CoV-2 inhibitors.

Aldehydes/chemistry , COVID-19/drug therapy , Chagas Disease/drug therapy , Cysteine Proteinase Inhibitors/therapeutic use , SARS-CoV-2/enzymology , Trypanosoma cruzi/enzymology , Aldehydes/metabolism , Aldehydes/pharmacology , Cathepsin L/antagonists & inhibitors , Cathepsin L/metabolism , Cysteine Endopeptidases/metabolism , Cysteine Proteases/metabolism , Cysteine Proteinase Inhibitors/chemistry , Drug Design , Humans , Kinetics , Models, Molecular , Molecular Structure , Protozoan Proteins/antagonists & inhibitors , Protozoan Proteins/metabolism , SARS-CoV-2/drug effects , Structure-Activity Relationship , Trypanosoma cruzi/drug effects