Synthesis, characterization, bioactivity, and POM analyses of isothiochromeno[3,4-e][1,2]oxazines
A series of 18 new 3,4-disubstituted-isothiochromeno[3,4-e][1,2]oxazines 28–45 has been obtained from the 3′,4′-di-substituted-4′H-spiro[isothiochromene-3,5′-isoxazol]-4(1H)-ones 10–27 in refluxing HCl acid/ethanol. A series of 15/18 compounds 28–45 was selected by the National Cancer Institute (NCI, Bethesda, USA) and were evaluated against a full panel of 60 primary human tumor cell lines derived from nine human cancer types, all of which showed antiproliferative activity in the micromolar range. The most active compound number 37 (S722910) showed high potency against all the tested cell lines with a GI50 mean value in the range of 30–80 μM; TGI and LC50 values were 12–16 μM having positive response on 98 and 63 % of the tested cell lines (Breast-MCF7 and NCS-SF-268) respectively.