benzofurans and Toxoplasmosis--Animal

Toxoplasma gondii pathogen is a threat to human health that results in economic burden. Unfortunately, there are very few high-efficiency and low-toxicity drugs for toxoplasmosis in the clinic. (+)-Usnic acid derived from lichen species has been reported to have anti-inflammatory, antibacterial, anti-parasitology, and even anti-cancer activities. Herein, the systematic effect of (+)-usnic acid and (+)-usnic acid-liposome on toxoplasma were studied in vitro and in vivo. The viability of toxoplasma tachyzoite was assayed with trypan blue and Giemsa staining; while the invasive capability of tachyzoite to cardiofibroblasts was detected using Giemsa staining. The survival time of mice and the changes in tachyzoite ultrastructure were studied in vivo. The results showed that (+)-usnic acid inhibited the viability of tachyzoite; pretreatment with (+)-usnic acid significantly decreased the invasion of tachyzoite to cardiofibroblasts in vitro; (+)-usnic acid and (+)-usnic acid-liposome extensively prolonged the survival time of mice about 90.9% and 117%, respectively; and improved the ultrastructural changes of tachyzoite, especially in dense granules, rhoptries, endoplasmic reticulum, mitochondria and other membrane organelles. In summary, these results demonstrate that (+)-usnic acid and (+)-usnic acid-liposome with low toxicity have an inhibitory effect on the viability of toxoplasma tachyzoite, and mainly destructed membrane organelles which are connected with the virulence of toxoplasma. These findings provide the basis for further study and development of usnic acid as a potential agent for treating toxoplasmosis.

Topics: Animals; Antiprotozoal Agents; Benzofurans; Cells, Cultured; Female; Fibroblasts; Liposomes; Male; Mice; Microscopy, Electron, Transmission; Myocytes, Cardiac; Random Allocation; Rats; Rats, Sprague-Dawley; Toxoplasma; Toxoplasmosis, Animal; Usnea

To explore the effect of usnic acid on Toxoplasma gondii tachyzoites in vitro.. There are four groups named as (+)-usnic acid group, acetylspiramycin group, DMSO group and normal saline group. Groups of (+)-usnic acid and acetylspiramycin were further divided into 4 subgroups with final concentration of 5, 10, 25, 50 microg/ml respectively. Normal saline group and DMSO group were respectively given equal volume normal saline and 1% DMSO. Each group have 15 parallel tubes with 1 ml (1 x 10(6)/ml) T. gondii tachyzoites aqueous suspension. At 1 h, 2h and 4 h after drug treatment, tachyzoites were counted by light microscope with 0.4% Trypan blue staining. Tachyzoites in aqueous suspension was collected, and washed 3 times by PBS solution. Normal mice were inoculated intraperitoneally and observed for three generations. The cultivated rat cardiofibroblasts were then infected in vitro with T. gondii tachyzoites. At the same time, rat cardiomyocytes invasion by T. gondii tachyzoites was investigated.. At 4 h treated by 10, 25 and 50 microg/ml (+)-usnic acid, 100% T. gondii tachyzoites were stained. Some tachyzoites were swelling, blunt or round in the two ends; and granules appeared in the cytoplasm, the nuclei were deep stained. The changes of tachyzoites in acetylspiramycin group were similar to (+)-usnic acid group, 100% T. gondii tachyzoites were stained in 50 microg/ml acetylspiramycin subgroup. In inoculation tests, mice died at 8th to 9th days in 5 microg/ml (+)-usnic acid subgroup and numerous tachyzoites were detected in ascites. However, most mice survived to be killed in the other (+)-usnic acid subgroups and the tachyzoites were not found in ascites. All mice in acetylespirmycin groups died at 6th to 8th days after inoculation and many tachyzoites or pseudocysts were observed in mice ascites. In infecting cell tests, the cultivated rat cardiofibroblasts were infected in vitro by the tachyzoites after treated with 5 microg/ml (+)-usnic acid for 4 h, and pseudocysts were formed in infected cells. It was negative in the other subgroups of (+)-usnic acid. But the cultivated rat cardiofibroblasts were infected to varying degree in acetylspiramycin groups, normal saline group and DMSO group.. (+)-Usnic acid has a remarkable effect on T. gondii tachyzoites.

Topics: Animals; Benzofurans; Cells, Cultured; In Vitro Techniques; Mice; Mice, Inbred Strains; Rats; Spiramycin; Toxoplasma; Toxoplasmosis, Animal