Anticancer activity of phenoxazines produced by bovine erythrocytes on colon cancer cells.

The present study investigated the anticancer activity of 2-aminophenoxazine-3-one (Phx-3) and 2-amino-4,4 alpha-dihydro-4 alpha,7-dimethyl-3H-phenoxazine-3-one (Phx-1), which were obtained by improved preparation methods using bovine erythrocyte suspension, on colon cancer cell lines COLO201, DLD1 and PMCO1 in vitro. The preparation methods for Phx-1 and Phx-3 had the advantages of extensively shortening reaction time and reducing sample volumes up to one-seventh during treatment, compared with the conventional method using bovine hemoglobin solution, resulting in extensive reduction of handling time. Phx-1 and Phx-3 thus obtained were identified as pure by the absorption spectra and NMR spectra. These phenoxazines exerted strong, dose-dependent anticancer activity against colon cancer cell lines COLO201, DLD1 and PMCO1 in vitro and induced apoptosis of these cells. The present results demonstrate that Phx-1 and Phx-3, which were prepared by extensively improved methods using bovine erythrocytes, may be useful as therapeutic drugs against colon cancer that is intractable to chemotherapy.