Structure optimization of new tumor-selective Passerini α-acyloxy carboxamides as Caspase-3/7 activators

Abstract

Selective elimination of tumors has always been the mainstay of oncology research. The on-going research underlying the cellular apoptotic mechanisms reveal caspases activation, especially the key effector caspase-3, as a personalized tumor-selective therapeutic strategy. Our continued research protocol has exploited new optimized Passerini α-acyloxy carboxamides as efficient apoptotic inducers via caspase-3/7 dependent mechanism with highly selective anticancer profiles. The adopted design rationale relied on excluding structural alerts of previous leads, while merging various pharmacophoric motifs of natural and synthetic caspase activators via optimized one-pot Passerini reaction conditions. The prepared compounds resulting from Passerini reaction were screened for their cytotoxic activities against colorectal Caco-2 and liver HepG-2 cancer cells compared to normal fibroblasts utilizing MTT assay. Notably, all compounds exhibited promising low-range submicromolar IC50 against the studied cancer cell lines, with outstanding tumor selectivity (SI values up to 266). Hence, they were superior to 5-fluorouracil. Notably, 7a, 7g, and 7j conferred the highest potencies against Caco-2 and HepG-2 cells and were selected for further mechanistic studies. Caspas-3/7 activation assay of the hit compounds and flow cytometric analysis of the treated apoptotic cancer cells demonstrated their significant caspase activation potential (up to 4.2 folds) and apoptotic induction capacities (up to 58.7%). Further assessment of Bcl2 expression was performed being a physiological caspase-3 substrate. Herein, the three studied Passerini adducts were able to downregulate Bcl2 in the treated Caco-2 cells. Importantly, the mechanistic studies results of the three hits echoed their preliminary MTT antiproliferative potencies data highlighting their caspase-3 dependent apoptotic induction. Finally, the in silico predicted physicochemical and pharmacokinetic profiles, as well as ligand efficiency metrics were drug-like.

Reinvestigation of Passerini and Ugi scaffolds as multistep apoptotic inducers via dual modulation of caspase 3/7 and P53-MDM2 signaling for halting breast cancer

“…Alternatively, Passerini reaction using 1 with trichloroacetic acid and cyclohexanone proceeded to afford the unexpected Passerini adduct ethyl 4-(2,4-dioxo-1-oxa-3-azaspiro[4.5]decan-3-yl)benzoate 14. 62 Saponification of 14 in NaOH followed by acidification led to the formation of 4-(1-(carboxyoxy)cyclohexane-1-carboxamido)benzoic acid 15 ( Scheme 4 ). The obtained monocarbonate ester 15 was confirmed by 1 H-NMR spectroscopy where two carboxylic protons showed a signal at δ H 12.66 ppm and one proton of –NH at δ H 10.04 ppm.…”

“…The application of the Ugi reaction generates a variety of biologically active molecules, which has attracted attention in recent years. [57][58][59][60][61] Herein, we utilized ethyl-4-isocyanobenzoate (1) as an entry to Passerini and Ugi products; it was prepared via esterication of 4-aminobenzoic acid to afford the ester; then, formylation using HCOOH/toluene protocol yielded the formamide, which underwent dehydration by Wang's method 62,63 to give the corresponding isonitrile, 1 in good yield.…”