Hydrothermally treated yeast cell wall suppresses the growth of MCF7 cells under isolated conditions.

Traditionally, yeast cell wall (YCW) has limited applications because of their low solubility. To overcome this, a novel method was developed using a hydrothermal reaction to enhance its solubility and decrease its viscosity; this resulted in the production of a soluble form of YCW, known as the YCW treated with hydrothermal reaction (YCW-H), with broader chemical composition. Therefore, in the present study, we aim to investigate YCW-H, a hydrothermally treated YCW product with enhanced solubility, for the inhibition of cancer cell proliferation. YCW-H promotes plant growth by effectively regulating soil microspheres. YCW-H inhibited the growth of MCF-7 breast cancer cells even after complete physical separation from the cells. This suggests the presence of a diffusible cytotoxic factor in YCW-H, a phenomenon not observed in the presence of untreated YCW. Since YCW-H possess reactive carbon species (RCS), we hypothesized that the reactive radical species generated during the hydrothermal treatment of YCW are responsible for this effect. The addition of Fe(III) ions to YCW-H further amplified the production of RCS and its inhibitory activity across the plastic barrier, correlating with the increased RCS levels. The radicals migrated to the water in wells adjacent to YCW-H, indicating that RCS generation is a key determinant of the inhibition of cancer cell growth. Moreover, compounds containing RCS were confirmed to exhibit cytotoxicity. Thus, our findings underscore the RCS-containing compounds from YCW-H as promising candidates for developing novel medical devices for cancer treatment.