TABLE 1.

Antimalarial activities of tetracyclinesa

Time of assay (h)IC50 (μM)
DoxycyclineMinocyclineTetracyclineChloroquine
Parasite counts
    484.8 ± 0.24.6 ± 0.222.3 ± 0.50.10 ± 0.02
    960.46 ± 0.070.14 ± 0.030.45 ± 0.010.083 ± 0.012
Hypoxanthine uptake
    4816.0 ± 3.010.8 ± 1.351.0 ± 1.00.13 ± 0.03
    961.02 ± 0.240.35 ± 0.081.27 ± 0.530.073 ± 0.006
  • a W2-strain parasites were incubated with drugs for 48 h, beginning at the late ring stage, and then analyzed or cultured for an additional 48 h in the absence of drugs before analysis. Ring stage parasitemias were determined by counting YOYO-1-stained infected erythrocytes by flow cytometry. Metabolic activity was assessed by quantitation of [3H]hypoxanthine uptake. IC50s are means ± standard errors of the mean from two independent experiments, each performed in duplicate.