Total Synthesis of Celastrol, Development of a Platform to Access Celastroid Natural Products
摘要:
Celastroid natural products, triterpenes, have been and continue to be investigated in clinical trials. Celastrol, and for that matter any member of the celastroid family, was prepared for the first time through chemical synthesis starting from 2,3-dimethylbutadiene. A triene cyclization precursor generated in 12 steps underwent a nonbiomimetic polyene cyclization mediated by ferric chloride to generate the generic celastroid pentacyclic core. In the cyclization, engagement of a tetrasubstituted olefin formed adjacent all carbon quaternary centers stereospecifically. With access to the carbocydic core of the family of natural products, wilforic acid and wilforol A were prepared en route to racemic celastrol.
Nur77, an orphan member of the nuclear receptor superfamily, plays an important role in the regulation of inflammatory processes. Our previous work found that celastrol, a pentacyclic triterpene, bound to Nur77 to inhibit inflammation in a Nur77-dependent manner. Celastrol binding to Nur77 promotes Nur77 translocation from nucleus to cytoplasm, resulting in clearance of inflamed mitochondria and then alleviation of inflammation. Here, we report the design, synthesis, SAR study and biological evaluation of a series of celastrol analogs. A total of 24 celastrol derivatives were made. Compound 3a with a K-d of 0.87 mu M was found to be less toxic than celastrol and could be a hit molecule for further optimization. (C) 2019 Elsevier Masson SAS. All rights reserved.
Discovery of semisynthetic celastrol derivatives exhibiting potent anti-ovarian cancer stem cell activity and STAT3 inhibition