Background: Plants and algae harbor diverse molecules with antioxidant activity and have been demonstrated to directly inhibit cancer cell growth and mitigate the oxidative damage associated with certain antitumor therapies. While antioxidant supplementation, either alone or in combination with chemotherapy, has shown promise in improving quality of life, further research is needed to explore the effects of antioxidant combinations on specific cancer cell lines. Methods: In this study, the in vitro cytotoxic and apoptotic properties of natural compounds derived from plants and algae, as well as certain dietary supplements, were investigated against various human cancer cell lines, including bone, leukemia, colorectal, breast, and prostate cancers. Results: Apple polyphenols, fucoxanthin, and plant-derived tocotrienols exhibited cytotoxic effects across all lines; however, tocotrienols demonstrated the most potent, time-dependent cytotoxic activity, with a half-inhibitory concentration (IC₅₀) of 4.3 μg/mL in bone cancer cells. Analysis of dietary supplements 2.1, 4.0, and 10.0 revealed that supplement 10.0 exhibited specific cytotoxic activity against bone cancer line TIB-223 and colorectal cancer cell line Caco2, with IC₅₀ values of 126 μg/mL and 158 μg/mL, respectively. Both tocotrienols and supplement 10.0 induced morphological changes in TIB-223 cells, inhibited cell migration (anti-metastatic activity), and promoted apoptosis, as evidenced by caspase 3/7 activation in both bone and colorectal cancer cells. Conclusions: These findings provide valuable insights for the development of targeted dietary supplements to enhance the anticancer effect of conventional chemotherapy in specific cancer types.

Plants and algae harbor diverse molecules with antioxidant activity that have been demonstrated to directly inhibit the growth of cancer cells and alleviate the oxidative damage side effects of certain antitumor therapies. Although supplementation with antioxidants alone or in combination with chemotherapy has shown promise in improving quality of life, further investigation is needed into the effects of antioxidant combinations on specific cancer cell lines. In this study, the in vitro cytotoxic and apoptotic properties of plant/algae natural compounds and dietary supplements were investigated on various human cancer cell lines, including bone, leukemia, colorectal, breast and prostatic cancers. Apple polyphenols, fucoxanthin, and plant tocotrienols exhibited cytotoxic effects across all lines, with tocotrienols particularly potent, showing a low half- inhibitory concentration (IC50) in bone cancer cells (4.3 μg/mL). Analysis of dietary supplements 2.1, 4.0 and 10.0, revealed that supplement 10.0 exhibited specific cytotoxic activity against the TIB-223 bone cancer line, with an IC50 of 126 μg/mL. Both tocotrienols and supplement 10.0, induced morphological changes, inhibited cell migration (anti-metastatic activity), and promoted apoptosis in TIB-223 cells, as demonstrated by caspase 3/7 activation. These findings provide valuable insights for the development of specific dietary supplements to enhance the anticancer effect of traditional chemotherapies for certain cancer types.