**5. Conclusions**

The inclusion of Ech into the carrageenan matrix enables a decrease the spermotoxicity of the Ech (besides protection of the substance from oxidation and improvement its solubility [11]), preserving its protective properties against the ROS synthesis by neutrophils, and the protective action towards the HT-29 intestinal epithelial cells.

**Author Contributions:** E.V.S. conceived, designed, performed and described the experiment for cytokines and ROS on blood cells and epithelial HT-29 cells, V.N.D. performed the experiments on a flow cytometer and assisted in publishing the article, N.I.M. performed the experiments with sea urchins, A.S.K. performed maintenance of HT-29 cells and co-contributed to experiments with these cells, N.P.M. contributed Ech for the research, A.O.K. provided all carrageenans samples, I.M.Y. described the experiments on sea urchin models and management of the manuscript writing process.

**Funding:** This work was supported by the Russian Science Foundation (RScF grant, project 16-14-00051).

**Acknowledgments:** The authors enormously appreciated the support provided by the organizing committee of "The 3rd International Symposium on Life Science" and especially Valentin A. Stonik for his invaluable comments.

**Conflicts of Interest:** The authors declare no conflict of interest.
