TMPRSS2 and COVID-19: HSD exhibits a higher binding affinity to proteins, specifically spike, ACE2, and TMPRSS2, than the previously used antivirals in COVID-19 therapy, lopinavir, nafamostat, and camostat.10,11 Hesperetin (HST), the HSD aglycon, is also present in the citrus peel, but at a lower amount than HSD.