Original Article

Effects of piperaquine on fine structure of erythrocytic stages of Plasmodium berghei ANKA strain

Authors: Lin CHEN, Yong-le QIAN, Ze-lin LI, Kui-han ZHANG, Bao-qiang DAI, Ze-fu LIU, Jing-jin WANG

Abstract

Piperaquine, 1, 3-bis[4-(7-chloroquinolyl-4)-piperazinyl-1]-propane, is superior to chloroquine in suppressing malaria parasites, even chloroquine-resistant I-III P. falciparum and with a relatively long preventive activity.
The effects of piperaquine (6.4 mg base/kg, the dose of ED50) on the fine structure of the erythrocytic stages of P.berghei ANKA strain indicated that piperaquine exerted its effects mainly on the amoeboid trophozoites. No marked effects on the ring forms, immature or mature schizonts, and male and female gametocytes were observed. A proportion of the trophozoites showed progressively morphological changes such as swelling of the food vacuole membrane 1 h after medication. At 4 h after exposure to piperaquine, there appeared in the parasites the swelling of mitochondria, proliferation of the multilamellate membrane body (MB) and enlarged digestive vacuoles containing round or oval pigment grains in clusters. In some trophozoites, the pigment grains exhibited a very dense appearance. The inter-membranous space between the outer and inner nuclear membranes was swollen. Occasionally, aggregations of chromatin material were prominent within the nucleus 12 h after medication. Autophagocytosis became so marked that most of the parasites were disintegrated and only some membranous residues remained 12-24 h after medication. These results suggest that piperaquine first interferes with the physiological function of the food vacuole membrane of the trophozoites.
For comparison, the effects of chloroquine on the fine structure of the parasites were also investigated.
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