NADH oxidase activity from sera altered by capsaicin is widely distributed among cancer patients

A cancer-specific form of NADH oxidase inhibited or stimulated by 1 or 100 microM capsaicin (8-methyl-N-vanillyl-6-noneamide) is present in sera from cancer patients. The capsaicin-inhibited NADH oxidase activity appears to be absent from sera of individuals free of cancer. The capsaicin-inhibited activity is present both in freshly collected sera and in sera stored frozen for varying periods of time. For the latter, an assay was carried out under renaturing conditions in the presence of NADH and reduced glutathione followed by dilute hydrogen peroxide. Inhibition was half maximal at about 1 microM capsaicin. The capsaicin-inhibited activity was found in sera over a broad spectrum of cancer patients including patients with solid cancers (e.g., breast, prostate, lung, ovarian) as well as with leukemias and lymphomas.