Synthesis and biological evaluation of 4-methylideneisoxazolidin-5-ones – A new class of highly cytotoxic α-methylidene-γ-lactones

Abstract

Two 4-methylideneisoxazolidin-5-ones ( 4a, b), which are α-methylidene-γ-lactones containing a nitrogen atom in the lactone ring, were synthesized. Their cytotoxic properties were evaluated against promyelocytic leukemia HL-60 cells. Both 4a and 4b exhibited relatively high cytotoxic activity with an IC 50 of 4.1 and 5.4 μM, respectively. Caspase-3 activity assay revealed that both isoxazolidinones ( 4) were able to induce apoptosis process in time- and concentration-dependent manner. Using multiplex PCR analysis, it was observed that 4 caused distinct inhibition of BCL-2 gene expression. Expression of BAX, a pro-apoptotic gene remained unchanged. It was also found that 4a, b did not induce the expression of MDR1 and MRP1 genes, related to multidrug resistance. In addition, cytotoxicity data obtained for drug-sensitive and drug-resistant HL-60 ADR cells revealed that the investigated compounds were poor substrates for transport by MRP1 efflux pump, suggesting that they might be useful for treating drug-resistant tumors. Furthermore, antimicrobial properties of 4a, b were evaluated. They showed significant activity against fungi Candida albicans, but only a weak activity against all tested Gram-positive and Gram-negative bacterial strains.