Inhibition of intramacrophage growth of Penicillium marneffei by 4-aminoquinolines

The antimicrobial activities of chloroquine (CQ) and several 4-aminoquinoli ne drugs were tested against Penicillium marneffei, an opportunistic fungus that invades and grows inside macrophages and causes disseminated infectio n in AIDS patients. Human THP1 and mouse J774 macrophages were infected in vitro with P, marneffei conidia and treated with different doses of drugs f or 24 to 48 h followed by cell lysis and the counting of P. marneffei CFU. CQ and amodiaquine exerted a dose-dependent inhibition of fungal growth, wh ereas quinine and artemisinin were fungistatic and not fungicidal, The anti fungal activity of CQ was not due to an impairment of fungal iron acquisiti on in that it was not reversed by the addition of iron nitrilotriacetate, F eCl3, or iron ammonium citrate. Perl's staining indicated that CQ did not a lter the ability of J774 cells to acquire iron from the medium. Most likely , CQ's antifungal activity is due to an increase in the intravacuolar pH an d a disruption of pH-dependent metabolic processes. Indeed, we demonstrate that (i) bafilomycin A1 and ammonium chloride, two agents known to alkalini ze intracellular vesicles by different mechanisms, were inhibitory as well and (ii) a newly synthesized 4-amino-7-chloroquinoline molecule (compound 9 ), lacking the terminal amino side chain of CQ that assists in drug accumul ation, did not inhibit P. marneffei growth. These results suggest that CQ h as a potential for use in prophylaxis of P. marneffei infections in human i mmunodeficiency virus-infected patients in countries where P. marneffei is endemic.