The emergence of viral respiratory pathogens with pandemic potential, such as severe acute respiratory syndrome coronavirus (SARS-CoV), the pathogenic agent of Covid-19, represent a serious health problem worldwide. Respiratory viral infections are, in general, associated with cytokine production, inflammation, cell death, and other pathophysiological processes, which could be link with a redox imbalance or oxidative stress. These phenomena are substantially increased during aging. Actually, severity and mortality risk of SARS-CoV-2 infection or Covid-19 disease have been associated with the age. The aim of the present work was to contribute with the understanding of the possible link between oxidative stress and the pathogenesis, severity and mortality risk in patients affected by SARS-CoV infection.

We have demonstrated that the peptide L-2 designed from an alanine scanning of the Limulus-derived LALF32-51 region is a potential candidate for the anticancer therapy and its cell-penetrating capacity is an associated useful property. By the modification in the primary structure of L-2, a second-generation peptide (CIGB-552) was developed. However, the molecular mechanism underlying its cytotoxic activity remains partially unknown. In this study, it was shown that CIGB-552 increases the levels of COMMD1, a protein involved in copper homeostasis, sodium transport, and the NF-κB signaling pathway. We found that CIGB-552 induces ubiquitination of RelA and inhibits the antiapoptotic activity regulated by NF-κB, whereas the knockdown of COMMD1 blocks this effect. We also found that CIGB-552 decreases the antioxidant capacity and induces the peroxidation of proteins and lipids in the tumor cells. Altogether, this study provides new insights into the mechanism of action of the peptide CIGB-552, which could be relevant in the design of future anticancer therapies.

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