AUTHOR=Thanvi Radhika , Jayasinghe Thilina D. , Kapil Sunayana , Obadawo Babatunde Samuel , Ronning Donald R. , Sucheck Steven J. 

TITLE=Synthesis of C7/C8-cyclitols and C7N-aminocyclitols from maltose and X-ray crystal structure of Streptomyces coelicolor GlgEI V279S in a complex with an amylostatin GXG–like derivative

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.950433

DOI=10.3389/fchem.2022.950433

ISSN=2296-2646

ABSTRACT=<p>C<sub>7</sub>/C<sub>8</sub>-cyclitols and C<sub>7</sub>N-aminocyclitols find applications in the pharmaceutical sector as α-glucosidase inhibitors and in the agricultural sector as fungicides and insecticides. In this study, we identified C<sub>7</sub>/C<sub>8</sub>-cyclitols and C<sub>7</sub>N-aminocyclitols as potential inhibitors of <italic>Streptomyces coelicolor</italic> (<italic>Sco</italic>) GlgEI-V279S based on the docking scores. The protein and the ligand (targets <bold>11</bold>, <bold>12</bold>, and <bold>13</bold>) were prepared, the states were generated at pH 7.0 ± 2.0, and the ligands were docked into the active sites of the receptor <italic>via</italic> Glide™. The synthetic route to these targets was similar to our previously reported route used to obtain 4-⍺-glucoside of valienamine (<bold>AGV</bold>), except the protecting group for target <bold>12</bold> was a <italic>p</italic>-bromobenzyl (PBB) ether to preserve the alkene upon deprotection. While compounds <bold>11</bold>–<bold>13</bold> did not inhibit <italic>Sco</italic> GlgEI-V279S at the concentrations evaluated, an X-ray crystal structure of the <italic>Sco</italic> GlgE1-V279S/<bold>13</bold> complex was solved to a resolution of 2.73 Å. This structure allowed assessment differences and commonality with our previously reported inhibitors and was useful for identifying enzyme–compound interactions that may be important for future inhibitor development. The Asp 394 nucleophile formed a bidentate hydrogen bond interaction with the exocyclic oxygen atoms (C(3)-OH and C(7)-OH) similar to the observed interactions with the <italic>Sco</italic> GlgEI-V279S in a complex with <bold>AGV</bold> (PDB:7MGY). In addition, the data suggest replacing the cyclohexyl group with more isosteric and hydrogen bond–donating groups to increase binding interactions in the + 1 binding site.</p>