New phosphorylated 5-(hydroxyalkylamino)-1,3-oxazoles as potential anticancer agents

Abstract

Eight new phosphorylated 5-(hydroxyalkylamino)-1,3-oxazoles were designed and tested for their ability to inhibit cancer cell growth. These compounds were evaluated against complete human tumor cell lines NCI-60. Only three compounds showed antitumor activity in the single dose assay, which were taken in the five dose assay. Compounds 7 and 8 showed the same average antiproliferative activity and cytotoxicity against sensitive cell lines of the general panel. However, compound 8 showed cytotoxicity to more lines than 7. By all parameters, these compounds were more active than compounds 5. Compounds 7 and 8 also showed high and similar antiproliferative activity in the concentration range GI50: 1-6 and TGI: 6-14 μM against all subpanels. Their cytotoxicity was in the concentration range of 25-54 μM. Compound 5 showed the same activity, with the exception of the leukemia, non-small cell lung cancer and ovarian cancer subpanels against which their activity was lower. When analyzing the structure-activity, it turned out that among the phosphorylated oxazole derivatives, only compounds containing the triphenylphosphonium cation (TPP+) in the 4th position of the oxazole ring exhibit antitumor activity. Moreover, the replacement of the phenyl radical in the 2nd position of the oxazole scaffold with a methyl radical led to the disappearance of the activity. The COMPARE algorithm reveals a high correlation of the antiproliferative activity of the tested compounds with the antitumor agents phyllantoside and chromomycin A3 in the GI50 vector and moderate with phyllantoside in the TGI vector. The target of all standard drugs that correlate with the cytotoxicity of the studied compounds, with the exception of didemnin, is DNA. Unlike standard compounds, synthesized active compounds carry a delocalized TPP+, which delivers them predominantly to mitochondria due to a much more hyperpolarized potential of the mitochondrial membrane in cancer cells than in normal ones. Therefore, their anticancer activity is most likely due to a disturbation of the structural and functional state of the latter due to interference with their intrinsic protein-synthesizing apparatus of mitochondria. The data obtained allow us to consider 5-(hydroxyalkylamino)-1,3-oxazoles loaded with TPP+ as leading compounds for further in-depth study and synthesis of new TPP+-containing 1,3-oxazole derivatives with antitumor activity