瑞香素对恶性疟原虫细胞色素C氧化酶及核糖核酸还原酶活性的影响

目的 体外测定瑞香素对恶性疟原虫细胞色素C氧化酶（COX）及核糖核酸还原酶（RNR）活性的影响。方法 Trager &; Jensen法体外培养恶性疟原虫FCC1/HN分离株，超声波破碎恶性疟原虫提取总蛋白，用紫外分光光度计检测瑞香素与瑞香素-Fe复合物在不同作用时间和不同作用浓度对恶性疟原虫COX活性的影响，以电子自旋共振法检测经瑞香素与瑞香素-Fe复合物作用1、2、3和4 h后，恶性疟原虫酪氨酸（Tyr）自由基的量以反映恶性疟原虫RNR的活性。 结果 体外同步培养的恶性疟原虫经瑞香素（100 μmol/L）作用2、4、8和12 h后，COX活性分别被抑制了0、6%、73%和80%；在瑞香素浓度为0.1、1、100和1 000 μmol/L，作用6 h后，COX活性分别被抑制3%、31%、53%和84%；而瑞香素-Fe复合物对COX的影响几乎消失。经瑞香素（100 μmol/L）作用1、2、3和4 h后RNR活性分别被抑制7%、51%、69%和75%；在瑞香素浓度为0.1、1、100和1 000 μmol/L，作用6 h后，RNR活性分别被抑制3%、31%、58%和93%；而瑞香素-Fe复合物作用6 h后RNR活性分别被抑制8%、6%、11%和9%。 结论 在体外瑞香素可显著降低恶性疟原虫的细胞色素C氧化酶（COX）及核糖核酸还原酶（RNR）活性。

In Vitro Effect of Daphnetin on Cytochrome C Oxidase andRibonucleotide Reductase of Plasmodium falciparum

OBJECTIVE: To test the in vitro effect of daphnetin on cytochrome C oxidase (COX) and ribonucleotide reductase (RNR) activity of Plasmodium falciparum. METHODS: P. falciparum (FCC1/HN) was cultured in vitro using the method of Trager and Jensen. The effect of daphnetin and daphnetin-Fe complex on COX and RNR activity of P. falciparum was tested by ultraviolet spectrophotometer and electron spin resonance (ESR) respectively. RESULT: The parasites synchronized with sorbitol in vitro was treated by daphnetin and daphnetin-Fe complex. The inhibition level of the COX activity by daphnetin after being treated for 2, 4, 8 and 12 h were 0.6%, 73% and 80% respectively and the inhibition level by daphnetin at different concentrations (0.1, 1, 100 and 1 mmol/L) for 6h was 3%, 31%, 53% and 84%, respectively. No considerable effect was observed on the COX activity of P. falciparum treated with daphnetin-Fe complex. The tyrosyl free radical was tested to reflect the RNR activity of P. falciparum at various times by ESR. The inhibition level by daphnetin for 1, 2, 3 and 4 h were 7%, 51%, 69% and 75% respectively, while the values treated by daphnetin-Fe complex were 8%, 6%, 11% and 9% respectively. The inhibition level by daphnetin at different concentrations (0.1, 1, 100 and 1 mmol/L) for 6 h was 3%, 31%, 58% and 93% respectively and while the values treated by daphnetin-Fe complex were 8%, 6%, 11% and 9%. CONCLUSION: Daphnetin significantly reduces the COX and RNR activities of Plasmodium falciparum in vitro.