Novel triterpenoid pyrones, phthalimides and phthalates are selectively cytotoxic in CCRF-CEM cancer cells - Synthesis, potency, and mitochondrial mechanism of action.

A series of triterpenoid pyrones was synthesized and subsequently modified to introduce phthalimide or phthalate moieties into the triterpenoid skeleton. These compounds underwent in vitro cytotoxicity screening, revealing that a subset of six compounds exhibited potent activity, with IC50 values in the low micromolar range. Further biological evaluations, including Annexin V and propidium iodide staining experiment revealed, that all compounds induce selective apoptosis in cancer cells. Measurements of mitochondrial potential, cell cycle analysis, and the expression of pro- and anti-apoptotic proteins confirmed, that apoptosis was mediated via the mitochondrial pathway. These findings were further supported by cell cycle modulation and DNA/RNA synthesis studies, which indicated a significant increase in cell accumulation in the G0/G1 phase and a marked reduction in S-phase cells, alongside a substantial inhibition of DNA synthesis. The activation of caspase-3 and the cleavage of PARP, coupled with a decrease in the expression of Bcl-2 and Bcl-XL proteins, underscored the induction of apoptosis through the mitochondrial pathway. Given their high activity and pronounced effect on mitochondria function, trifluoromethyl pyrones 1f and 2f, and dihydrophthalimide 2h have been selected for further development.

Lupane derivatives containing various aryl substituents in the position 3 have selective cytostatic effect in leukemic cancer cells including resistant phenotypes.

In this work, a large set of betulinic acid derivatives modified with various aromatic substituents at the position C-3 were prepared via Suzuki-Myiaura cross-coupling. All compounds were tested for their in vitro cytotoxic activity in 8 cancer and 2 healthy cell lines. Derivatives 6h, 6i, and 6o had the lowest IC50 in the CCRF-CEM cell line (0.69-4.0 µM) and had high selectivity. In addition, 6h and 6i also showed significant activity in daunorubicin-resistant CEM and taxol-resistant K562 cell lines; therefore, they were selected for the evaluation of the mechanism of action. First, the effect of 6h, 6i, and 6o on cell death induction was studied. To our surprise, we have not detected almost any apoptotic cells, even following a long-time exposure of CCRF-CEM cells to the compounds. On the other hand, a dramatic cell number decrease was observed, proportional to the time of the compound's exposure. Based on this data it was concluded that the effect of compounds is cytostatic rather than cytotoxic, which was further confirmed by subsequent studies of the impact of 6h, 6i, and 6o on the cell cycle. Detailed cell cycle analysis revealed a block in the G1 phase accompanied by reduced expression of phosphorylated forms of the RB protein as well as cyclin A protein. Evaluation of the pharmacological properties of the most promising compounds revealed their high stability in the presence of phosphate buffer, human plasma, and microsomes and limited permeability determined using permeability through artificial membrane (PAMPA) and cell permeability assay: Caco-2 and MDCK-MDR1 cell lines. Compounds 6h, 6i, and 6o were selected for further drug development; their cytostatic effect may be advantageous in this process since we expect fewer non-specific interactions and toxicity than in highly cytotoxic compounds. In addition, the activity of 6h and 6i against resistant CEM-DNR and K562-TAX leukemic cell lines makes them promising as a possible future alternative to currently used therapies.

Synthesis and biological evaluation of triterpenoid thiazoles derived from betulonic acid, dihydrobetulonic acid, and ursonic acid.

In this work, 35 new derivatives of betulonic, dihydrobetulonic and ursonic acid were prepared including 30 aminothiazoles and all of them were tested for their in vitro cytotoxic activity in eight cancer cell lines and two non-cancer fibroblasts. Compounds with the IC50 below 5 µM in CCRF-CEM cells and low toxicity in non-cancer fibroblasts (4m, 5c, 5m, 6c, 6m, 7b, and 7c) were further subjected to tests of pharmacological parameters yielding the final set for advanced biological evaluation (4m, 5m, 6m, and 7b). It was proved by several methods, that all of them trigger apoptosis via the intrinsic pathway and derivatives 5m and 7b are the most effective (IC50 2.4 µM and 3.6 µM). They are the best candidates to become potentially new anticancer drugs and will be subjected to in vivo tests in mice. In addition, compounds 6b and 6c deserve more attention because their activity is not limited only to chemosensitive CCRF-CEM cell line. Specifically, compound 6b is highly active against K562 leukemic cell line (0.7 µM) and its IC50 activity in colon cancer HCT116 cell line is 1.0 µM. Compound 6c is active in both normal K562 and resistant K562-TAX cell lines (IC50 3.4 µM and 5.4 µM) and both colon cancer cell lines (HCT116 and HCT116p53-/-, IC50 3.5 µM and 3.4 µM).