Targeting Inactive Enzyme Conformation: Aryl Diketoacid Derivatives as a New Class of PTP1B Inhibitors

Abstract

There has been considerable interest in protein tyrosine phosphatase 1B (PTP1B) as a therapeutic target for diabetes, obesity, as well as cancer. Identifying inhibitory compounds with good bioavailability is a major challenge of drug discovery programs targeted toward PTPs. Most current PTP active site-directed pharmacophores are negatively charged pTyr mimetics which cannot readily enter the cell. This lack of cell permeability limits the utility of such compounds in signaling studies and further therapeutic development. We identify aryl diketoacids as novel pTyr surrogates and show that neutral amide-linked aryl diketoacid dimers also exhibit excellent PTP inhibitory activity. Kinetic studies establish that these aryl diketoacid derivatives act as noncompetitive inhibitors of PTP1B. Crystal structures of ligand-bound PTP1B reveal that both the aryl diketoacid and its dimeric derivative bind PTP1B at the active site, albeit with distinct modes of interaction, in the catalytically inactive, WPD loop open conformation. Furthermore, dimeric aryl diketoacids are cell permeable and enhance insulin signaling in hepatoma cells, suggesting that targeting the inactive conformation may provide a unique opportunity for creating active site-directed PTP1B inhibitors with improved pharmacological properties.

Two new botcinin derivatives encountered in the studies of secondary metabolites from the marine-derived fungus Botryotinia sp. SF-5275

“…This observation, together with the observed difference in mass, suggested that compound 2a possesses an alkyl chain with two additional methylene units as compared with that of compound 1a. Further interpretation of COSY, HSQC and HMBC NMR data for 2a (Table 2) allowed assignment of all 1 H and 13 C NMR resonances, and confirmed the proposed structure. Analysis of coupling constants and comparisons with corresponding values in compound 1a indicated that 2a has the same relative configuration as that of 3-O-acetylbotcinic acid methyl ester (1a).…”

Monosaccharide as a Central Scaffold Toward the Construction of Salicylate-Based Bidentate PTP1B Inhibitors via Click Chemistry

“…4, 138.1, 128.5, 128.4, 128.3, 128.2, 128.0, 127.8, 98.1, 81.7, 80.4, 79.6, 79.5, 76.9, 75.2, 75.1, 74.3, 73.4, 69.7, 68.0, 60.5, 58.6, 55.2 71 (m, 2H), 3.51-3.47 (m, 2H), 3.38 (s, 3H), 2.45-2.44 (m, 2H); 13 C NMR (100 MHz, CDCl 3 ) δ 138. 6, 138.0, 128.5, 128.4, 128.2, 128.1, 128.0, 127.0, 98.2, 81.8, 80.1, 79.6, 79.3, 77.0, 75.8, 75.0, 74.3, 73.4, 69.5, 68.1, 60.1, 58.6, 55.3 (6). To a solution of 6' in anhydrous DMF at 0 °C, NaH (5 equiv.)…”

“…The combined organic layers were dried over MgSO 4 , filtered and concentrated to give the crude product which was eventually purified by column chromatography. Yellow-brown syrup (56% for 3 steps); [α] 2 Hz,1H),3H),3.66 (dd,J = 3.6 Hz,6.0 Hz, 1H), 3.56 (t, J = 9.2 Hz, 1H), 3.44 (s, 3H), 2.44 (brs, 1H), 2.40 (brs, 1H);…”

“…5 Meanwhile, noncompetitive inhibitors identified such as the aryl diketoacid derivatives that target the open conformation of WPD loop also enabled an alternative way for PTP1B inhibition. 6 As shown in Figure 1, we have recently synthesized series of triazolyl salicylate-hydroxyl O-glycoside conjugates via Cu(I)-catalyzed azide-alkyne 1,3-cycloaddition (click reaction). 7 The sequential inhibitory assay identified these compounds as weak PTP1B inhibitors, (IC 50 > 50 µM) possibly due to the lack of hydrophobic moieties for generating nonpolar interactions with the proper enzymatic surface.…”

“…7 The sequential inhibitory assay identified these compounds as weak PTP1B inhibitors, (IC 50 > 50 µM) possibly due to the lack of hydrophobic moieties for generating nonpolar interactions with the proper enzymatic surface. 6,7 As a result, we seek to continuously progress our study toward the preparation of new PTP1B inhibitors based on triazole-linked salicylic O-glycosides which simultaneously comprise aryl groups via the versatile click chemistry. [8][9][10] The strategy for preparing 'bidentate' inhibitors simultaneously access the catalytic site and a neighboring pocket such as the second phosphotyrosine site 11 or the YRD motif has proven efficacious to achieve potent and selective PTP1B inhibition.…”