Table 1.

Main biological activities of chloroquine (CQ) and hydroxychloroquine (HCQ) as anti-viral drugs.

Biological activity	References
Inhibition of viral attachment and entry in the host cell
Inhibition of the biosynthesis of sialic acids •inhibition of the N-glycosylation of the cell surface viral receptor ACE2 •inhibition of the N-glycosylation of the viral spike (S) proteins •inhibition of the synthesis of cell membrane sialic acids	[12] [ 12,13] [14]
Inhibition of PICALM expression and CME	[15,16]
Endosomal alkalinization and inhibition of cellular endosomal protease (cathepsin and/or TMPRSS2)	[17]
Inhibition of new viral particle maturation and spread
Endosomal alkalinization and inhibition of endosome-lysosome membrane fusion	[18]
ERGIC and TGN vesicle alkalinization and inhibition of post-translational modifications of viral proteins	[7,19,20]
ERGIC vesicle alkalinization and inhibition of viral budding	[21]
Inhibition of p38 MAPK activation	[23,24]
Inhibition of phospholipase A2 and membranous structures essential for replication and transcription	[35]