ACE2 and viral infectious disease: Both these latter two classes of biomolecules are anti-oxidants [17,28,66] and, in some cases, they can directly inhibit plaque formation or inhibit binding of Spike proteins to host-cell receptor ACE2, or also been involved as protease inhibitors, helping to avoid virus entry or stop virus infection (e.g., HIV, SARS, MERS) [19,67,68].