Synthesis and biological evaluation of parthenolide derivatives with reduced toxicity as potential inhibitors of the NLRP3 inflammasome

Parthenolide (PTL) can target NLRP3 inflammasome to treat inflammation and its related disease, but its cytotoxicity limits further development as an anti-inflammatory drug. A series of PTL analogs and their Michael-type adducts were designed and synthesized, and most of them showed high activities against the NLRP3 inflammasome pathway. The most potent compound 8b inhibited the release of IL-113 with IC50 values of 0.3 mu M in J774A.1 cell and 1.0 mu M in primary glial cells, respectively. Moreover, 8b showed low toxicity against J774A.1 cell (IC50 = 24.1 mu M) and HEK-293T (IC50 = 69.8 mu M) with a similar to 8 folds increase of therapeutic index compared to its parent PTL. The preliminary mechanism study revealed that 8b mediated anti-inflammation is associated with the NLRP3 inflammasome signal pathway. Based on these investigations, we propose that 8b might be a potential drug candidate for ultimate development of the anti-inflammation drug.