Chloroquine (phosphate)

Chloroquine phosphate is an antimalarial and anti-inflammatory agent widely used to treat malaria and rheumatoid arthritis. Chloroquine phosphate is an autophagy and toll-like receptors (TLRs) inhibitor. Chloroquine phosphate is highly effective in the control of SARS-CoV-2 (COVID-19) infection in vitro (EC₅₀=1.13 μM)^[1][2][3][4]. IC50 & Target:Parasite, Autophagy, SARS-COV-2, TLRs, HIV^[1][2][3][4] In Vitro: Chloroquine (CHQ, 20 μM) inhibits IL-12p70 release and reduces Th1-priming capacity of activated human monocyte-derived Langerhans-like cells (MoLC). Chloroquine (CHQ, 20 μM) enhances IL-1–induced IL-23 secretion in MoLC and subsequently increases IL-17A release by primed CD4⁺ T cells^[1]. Chloroquine (25 μM) suppresses MMP-9 mRNA expression in normoxia and hypoxia in parental MDA-MB-231 cells. Chloroquine has cell-, dose- and hypoxia-dependent effects on MMP-2, MMP-9 and MMP-13 mRNA expression^[2]. TLR7 and TLR9 inhibition using IRS-954 or chloroquine significantly reduces HuH7 cell proliferation in vitro^[3].
Chloroquine (0.01-100 μM; 48 hours) potently blocks virus infection (vero E6 cells infected with SARS-CoV-2) at low-micromolar concentration (EC₅₀= 1.13 μM). Chloroquine blocks virus infection by increasing endosomal pH required for virus/cell fusion, as well as interfering with the glycosylation of cellular receptors of SARS-CoV^[4]. In Vivo: Chloroquine (80 mg/kg, i.p.) does not prevent the growth of the triple-negative MDA-MB-231 cells with high or low TLR9 expression levels in the orthotopic mouse model^[2]. TLR7 and TLR9 inhibition using IRS-954 or chloroquine significantly inhibits tumour growth in the mouse xenograft model. HCC development in the DEN/NMOR rat model is also significantly inhibited by chloroquine^[3].