Abstract: AIM: To understand the relationship between polyamine metbolism and pyronaridine resistance of
malaria parasites.METHODS: Kunming strain mice weighing 18 g-22 g were inoculated intraperitoneally with
Plasmodium berghei ANKA strain (pyronaridine sensitive, PS), and P. berghei ANKA strain low and high pyronaridine resistant lines(PRA and PRB), respectively. Seven days after inoculation,blood samples were
collected and WBC in the blood were removed by the method of chromatography using SE-cellulose and Sephadex G25 (1 ∶2). After thin layer chromatography, the contents of three polyamines, ie. putrescine (PTC) , spermidine (SPD) , and spermine (SPM ) in normal and infected eryth rocytes were determined with fluorescence spectrometer. The changes of polyamine level in PS and PRB infected erythrocytes of mice treated by a single oral dose of PND 5 and 10 mg/kg re-spect ively were also observed. RESULTS: The contents of PTC, SPD and SPM in PS infected erythrocytes were 47.5±28.6, 97.7±34.0 and 81.7±23.8 nmol/109 RBC (n= 9) , respectively, being 1.5, 3.5, and 616 times of those appeared in thenormal RBC (32.0±9.9, 28.2±12.3, and 12.4±15.0 nmol/109 RBC, n= 9) , respectively. The differences between two groups were significant. Interestingly, when mice infected with pyronaridine resistant line PRA and PRB, the contents of PTC, SPD and SPM in the infected erythrocytes increased to 187.7±139.9, 258.3±137.9 and 142.8±143.8 nmol/109 RBC (n=18) , and 345.5±223.0, 435.8±265.4 and 189.4±171.7 noml/109 RBC, respectively. Except for SPM , PTC and SPD in the PRA and PRB infected erythrocytes were significantly higher than those in the PS and PRA infected erythrocytes, respectively, being 3.9, 2.6 and 1.8, 1.7 times of those appeared in PS and PRA infected erythrocytes. In PND treated group, SPD and SPM contents of PS infected erythrocytes were decreased by 31.6% and 47.3% compared with non-treated group, but the polyamine level of PRB infected erythrocytes did not significantly change after PND administration. CONCLUSION∶ The resistance of P.berghei to PND is related to the alteration of polyamine metabolism in them alarial parasites.

Key words: Plasmodium berghei, pyronaridine, drug resist ance, polyamine, putrescine, spermidine, spermine