松萝酸抗弓形虫速殖子作用的体外实验和电镜观察

EXPERIMENTAL RESEARCH AND ELECTRON MICROSCOPY ON THE KILLING EFFECT OF USNIC ACID ON TOXOPLASMA GONDII TACHYZOITE IN VITRO

目的：了解松萝酸在试管内杀弓形虫速殖子的效果及其机制。方法：将松萝酸（终浓度５－５０μｇ／ｍｌ）加入小鼠腹水中（含虫１×１０６个／ｍｌ），以螺旋霉素作对照。用光镜和透射电镜观察，并将药物作用４ｈ的速殖子接种于小鼠以观察虫体能否复苏。结果：经１０μｇ／ｍｌ松萝酸作用３０ｍｉｎ，即可见速殖子的棒状体后段中央部分被溶解，细胞膜相结构和子虫的细胞膜断裂。经５０μｇ／ｍｌ松萝酸作用４ｈ的虫体在小鼠体内未能复苏。螺旋霉素的杀虫效果不及相同浓度的松萝酸。结论：松萝酸在体外对弓形虫速殖子有杀灭作用，可以抑制速殖子的侵袭力和繁殖。该药的杀虫力与药物的浓度和作用时间呈正相关趋势。松萝酸的杀虫效果优于螺旋霉素。

AIM: To study the anti Toxoplasma effect of usnic acid in vitroand its mechanism . METHOD: After usnic acid (final concentration 5-50 μg/ml) was added into the ascites of experimentally infected mice for 30 min-4 h, the effect was observed under light microscope and transmission electron microscope. Spiramycin was used as control. In addition, mice were inoculated with the drug treated tachyzoites. RESULTS: Under the action of 10 μg/ml usnic acid for 30 min, the rhoptries lysed and the daughter cell membrane and membranate structures of tachyzoites appeared broken. The tachyzoites treated by 50 μg/ml usnic acid for 4 h could not be recovered in the inoculated mice. The toxoplasmacidal effect of spiramycin was inferior to that of usnic acid at the same concentration. CONCLUSION: Usnic acid could kill Toxoplasma gondii tachyzoites in vitro. The penetration and multiplication of the tachyzoites could be inhibited by usnic acid. The toxoplasmacidal activity of the drug has positive correlation with the concentration and the time of action of usnic acid. The toxoplasmacidal effect of usnic acid was proved to be more remarkable than that of spiramycin.