Effects of artesunate, pyronaridine and hydroxypiperaquine on chloroquine-sensitive and chloroquine-resistant isolates of Plasmodium falciparum in vitro

The effects of three new anti-malarials are reported on both chloroquine (CQ)-sensitive and CQ-resistant isolates of Plasmodium falciparum from different regions of China by 48-h in vitro microtechnique. The results showed that the recent isolates Jiangsu FCC-102/JS,Anhui FCC-IOI /AH and control strain FCC-1/HN were CQ-sensitive ones with ICso of 56 +8 nmol/L; and the other two FCC-4/HN, FCC-5/HN from Hainan and Cambodian-I strains were CQ-resistant ones with IC50 of 322+69 nmol/L and a mean resistant index of 5.7. No significant difference of sensitivity to artesunate (AS), pyronaridine (PN) and hydroxypiperaquine (HPQ) was detected between the CQ-sensitive and CQ-resistant isolates. The IC50 of AS, PN or HPQ was 7.5 + 1.8, 15.2 +2.0 or 42 +8 nmol/L, respectively, and therefore the effects of these new drugs were apparently stronger than that of CQ.