ACE2 and viral infectious disease: In summary, these works clearly demonstrate the antiviral effect of the different triterpenes, such as MA, BA, and UA, derived from the olive tree, as well as other terpenoids from other natural sources, by significantly inhibiting different SARS-CoV-2 proteases, such as major viral protease (3CL-Pro) with IC50 values between 3.2 and 14.4 μM, the PL-Pro (papain-like protease), the SGp-RBD (spike glycoprotein receptor binding domain), the RdRp (RNA polymerase RNA-dependent), and ACE2 (angiotensin-converting enzyme 2), all key to understanding viral infection.