Quinoxaline chemistry. Part 11. 3-Phenyl-2 [phenoxy- and phenoxymethyl]-6(7) or 6,8-substituted quinoxalines and N-[4-(6(7)-substituted or 6,8-disubstituted-3-phenylquinoxalin-2-yl)hydroxy or hydroxymethyl]benzoylglutamates. Synthesis and evaluation of in vitro anticancer activity and enzymatic inhibitory activity against dihydrofolate reductase and thymidylate synthase

Twenty-four out of twenty-nine quinoxalines were selected at the National Cancer Institute, Bethesda, Md, USA, for in vitro anticancer screening. Among these, 10 derivatives exhibited high values of percent tumor growth inhibition at a concentration of 10−4 M in all cancer cell lines. Four of these compounds maintained these values at 10−5 M, whereas a certain number exhibited significant values of percent inhibition at the most diluted concentrations (10−8 – 10−6 M). Inhibitory activity against dihydrofolate reductase (DHFR) (bovine and rat liver) was determined for the most active compounds. This test showed that this type of quinoxaline exhibited an appreciable activity in comparison with the previously described aza analogues. In the other test (Lactobacillus casei, thymidylate synthase (TS), human HTS) no or poor activity was detected in both series of compounds.