Cancer cells contain higher levels of ROS (Reactive Oxygen Species) and RNS (Reactive Nitrogen Species) than normal cells. The increased levels of ROS/RNS in cancer cells stimulate proliferation as well as metastasis processes. Therefore, maintaining the level of these reactive species is an important factor in antitumor therapy. Bifidobacterium animalis subsp. lactis (BAL) probiotics have been attracting much attention for the last few years due to the increasingly noticeable results in the field of anticancer activity. These live microbes in combination with food products, such as mushrooms, have great potential in cancer therapy.

This study aimed to examine the individual antioxidant effect of the probiotic BAL on HeLa cells (cervical cancer cell line), as well as its activity in co-treatment with the ethyl acetate extract of the mushroom L. sulphureus (EALS – concentration 10 µg/mL). NBT assay was used to quantify superoxide anion radicals' level (O₂^.-), Griess assay for NO₂^-, and glutathione test for GSH according to standard procedures. Cervical cancer cells were incubated with treatments in a modified 2D co-culture system, and the results were evaluated after 12 and 24 h.

Our results suggest a strong antioxidant activity of BAL probiotics on HeLa cells. The levels of ROS and RNS, as well as GSH, remained at significantly low levels compared to the control. This is especially important if we consider that it is favorable for cancer cells to have reactive species elevated. On the other hand, in the BAL/EALS 10 µg/mL treatment, the parameters of oxidative status were higher compared to BAL, which indicates that the EALS extract slightly reduced the antioxidant activity of the tested probiotic. Overall, the results of this study indicate that BAL and BAL/EALS 10 µg/mL treatments are valuable subjects for future studies of antioxidative activity in HeLa cells.