A facile synthesis of novel indazole-fused pyrazoles
from pyrazol-3-ones and alkynoate esters/amides via Rh(III)-catalyzed
sequential C–H activation/ortho-alkenylation/intramolecular
cyclization cascade is reported. The important characteristic of this
method is that the resulting scaffold bearing quaternary carbon has
been obtained through unusual [4 + 1] rather than expected [4 + 2]
addition where alkynoate acts as a one-carbon unit.
Rh(III)-catalyzed cascade C-H activation and cyclization of 2-aryl benzimidazoles with maleimides for the synthesis of benzimidazole-fused isoquinolines and benzimidazole spiro isoindoles is reported. The switchable selectivity in the formation of...
The S100A1 protein in humans is a calcium-binding protein. Upon Ca2+ binding to S100A1 EF-hand motifs, the conformation of S100A1 changes and promotes interactions with target proteins. RAGE consists of three domains: the cytoplasmic, transmembrane, and extracellular domains. The extracellular domain consists of C1, C2, and V domains. V domains are the primary receptors for the S100 protein. It was reported several years ago that S100A1 and RAGE V domains interact in a pathway involving S100A1-RAGE signaling, whereby S100A1 binds to the V domain, resulting in RAGE dimerization. The autophosphorylation of the cytoplasmic domain initiates a signaling cascade that regulates cell proliferation, cell growth, and tumor formation. In this study, we used pentamidine and a newly synthesized pentamidine analog (WLC-4059) to inhibit the S100A1-RAGE V interaction. 1H-15N HSQC NMR titration was carried out to characterize the interaction between mS100A1 (mutant S100A1, C86S) and pentamidine analogs. We found that pentamidine analogs interact with S100A1 via 1H-15N HSQC NMR spectroscopy. Based on the results, we utilized the HADDOCK program to generate structures of the mS100A1–WLC-4059 binary complex. Interestingly, the binary complex overlapped with the complex crystal structure of the mS100A1–RAGE-V domain, proving that WLC-4059 blocks interaction sites between S100A1 and RAGE-V. A WST-1 cell proliferation assay also supported these results. We conclude that pentamidine analogs could potentially enhance therapeutic approaches against cancers.
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