[Antiprotozoal Activities of Eucalyptus Extracts and Their Chemical Components].

Eucalyptus is a fast-growing plant with rich activities. The roots, stems and leaves of Eucalyptus all have medicinal values. Extracts from different parts of various kinds of Eucalyptus show antiparasitic effects, not only the repelling and killing effects on ectoparasites such as ticks and mites, but also the antiparasitic activities against endoparasites such as helminth and protozoa. This paper reviews the effects of Eucalyptus extracts and their chemical componets on protozoa including flagellates, sporozoan and ciliates.

[In vitro Killing Effect of Eucalyptus robusta Leaves Extract on Echinococcus granulosus Protoscolices].

Objective: To investigate the effect of Eucalyptus robusta leaves extract against Echinococcus granulosus protoscolices in vitro. Methods: Mature leaves of Eucalyptus robusta were collected on 24th day in each month from January to December 2012, and air-dried in the room. Ultrasonic extraction of the leaves was done with 4 solvents with different polarity, petroleum ether, dichloromethane, ethyl acetate and anhydrous ethanol. Protoscolices were incubated with the extract at various concentrations for 72 h, and mortality and median lethal dose（LC50） was calculated. Results: The extracts were different in characteristics and yield. The petroleum ether extract was in the form of black oil, while dichloromethane, ethyl acetate and anhydrous ethanol extracts were in the form of dark green, pink and white powder respectively. The average yields by petroleum ether, dichloromethane, ethyl acetate, and anhydrous ethanol were 4.4%, 2.1%, 2.3% and 2.3%, respectively. The extract yield was highest for petroleum ether, with a yield of 5.4% in May. The mortality of protoscoleces in all monthly groups of petroleum ether and dichloromethane extracts reached 100% with the concentration of 100 µg/ml and the same mortality reached in most groups of petroleum ether extracts with the concentration of 50 µg/ml. The effects of dichloromethane extracts were less than petroleum ether extracts, but significantly stronger than those of ethyl acetate and ehanol extracts. Further studies conducted on petroleum ether and dichloromethane extracts showed, the lethal effect of petroleum ether extract ranked in month of preparation from strong to weak as June>March>November>April>February>May>October>August>December>July>January>September. In June, the LC50 was 2.577 µg/ml and 95% confidence interval was 0.85-6.22 µg/ml. The lethal effect of dichlorom ethane extract ranked in month of preparation from strong to weak as November>May>October>April>July>December>June>September>August>February>March>January. In November, the LC50 was 21.85 µg/ml, and 95% confidence interval was 12.38-36.28 µg/ml. Conclusion: The Eucalyptus robusta leaves contain potential compounds against Echinococcus granulosus. Further experiments of isolation, analysis and identification are needed.

[In Vitro Effects of Aminoalcohol-carbazole Compound BTB3 against Echinococcus granulosus].

Objective: To evaluate the effects of a aminoalcohol-carbazole compound BTB3 against Echinococcus granulosus in vitro. Methods: The protoscoleces from sheep and germinal cells from secondary-infected mice were cultured and treated with 1, 2, 4, 8, 10 and 20 µg/ml BTB3 for 3 days. The viability of protoscoleces and cells was determined by the methylene blue exclusion method and CCK-8 assay. Meanwhile, the effect of 10 µg/ml BTB3 on germinal cells was assessed by scanning electron microscopy（SEM）. The metacestodes were treated with 1, 5 and 10 µg/ml BTB3 for two weeks, and the integrity of the metacestodes was evaluated by SEM. Results: The 10 µg/ml and 20 µg/ml BTB3 caused a death rate of （100.0±0.0）% and （85.2±7.2）% respectively for protoscoleces. As the concentration decreased, the death rate remained below 10%. Moreover, the activity inhibition rate on germinal cells was about 100% for 8, 10 and 20 µg/ml BTB3, and was reduced with the decrease of BTB3 concentration other than the afore-mentioned three. SEM revealed detachment, shrinkage, and cavitation of germinal cells after BTB3 treatment. And the metacestodes all showed the loss of turgidity after BTB3 treatment for 14 days, which indicated cell detachment and uneven distribution of cells in internal cyst of metacestodes. Conclusion: BTB3 has strong effects against Echinococcu granulosus protoscoleces, germinal cells and metacestodes in vitro, which make it a potential drug against hydatid diseases.

Significance of higher drug concentration in erythrocytes of mice infected with Schistosoma japonicum and treated orally with mefloquine at single doses.

The purpose of the present study is to understand the pharmacokinetic feature of mefloquine measured by erythrocytes and plasma in Schistosoma japonicum (S. j.)-infected mice and non-infected mice after oral administration of the drug at single doses. A high-performance liquid chromatography (HPLC) method was used to measure the plasma and erythrocyte concentrations of mefloquine at varying intervals posttreatment. Our results demonstrated that in non-infected mice treated orally with mefloquine at an ineffective dose of 50 mg/kg or effective dose of 200 mg/kg for 2-72 h, the erythrocyte-to-plasma ratios of mefloquine were 5.8-11.2 or 2-14.2. On the other hand, in S. j.-infected mice treated with the same single doses of the drug, the erythrocyte and plasma drug concentration ratios were 3.1-4.6 or 2.9-8.5, manifesting that either in infected mice or in non-infected mice that received oral mefloquine resulted in higher concentration of mefloquine in erythrocytes than that in plasma. Unexpectedly, under oral administration of mefloquine at a higher single dose of 200 mg/kg, the pharmacokinetic parameter C max values for plasma from S. j.-infected and non-infected mice were 1.6 ± 0.3 and 2.0 ± 0.4 µg/mL, respectively, which were below the determined in vitro LC50 (50 % lethal concentration) value of 4.93 µg/mL. Therefore, the plasma concentration of mefloquine may display a little effect against schistosomes during the treatment. Although the values of T 1/2 and AUC0-∞ for erythrocytes were significantly longer and higher in infected mice than those of corresponding non-infect mice that received the same single mefloqine dose of 50 mg/kg, the C max value was only 2.6 ± 0.4 µg/mL lower than the determined in vitro LC50, which may explain why this low single dose is ineffective against schistosomes in vivo. After administration of higher mefloquine dose of 200 mg/kg, the C max value for erythrocytes in infected mice was 30 % (7.4 ± 0.7 versus 10.7 ± 2.7 µg/mL) lower than that in the corresponding non-infected mice, but its level was above the determined in vitro LC95 (95 % lethal concentration) value of 6.12 µg/mL. Meanwhile, longer T 1/2 value of 159.2 ± 129.3 h in infected mice led to significant increase in AUC0-∞ value (1969.3 ± 1057.7 vs 486.4 ± 53.0 µg/mL·h), relative to corresponding non-infected mice. In addition, the mean residence time (MRT0-∞) in infected mice was also significantly longer than that in non-infected mice. All these results may beneficial for the treatment. According to the results, we suggest that higher ratios of mefloquine concentration in erythrocytes to plasma may offer a way to transport mefloquine to the worm gut through ingestion of erythrocytes by the worms, where the gut is the site for displaying the effect by mefloquine.

[Controlled Veterinary Drug Delivery Systems against Parasitic Infection].

Parasitic infections, especially the gastrointestinal and lung nematode infections, are most common in livestock in temperate areas, and it is the major constraints affecting livestock production. In grazing season, outdoor activities of animals cause inconvenience to the application of antiparasitic drugs. Therefore, controlled drug delivery systems can prolong the effect time and reduce the difficulty of drug administration. This review summarizes several types of long-term delivery devices and dosage forms including intraruminal devices, long-acting injectables, in-situ forming implants, novel microparticles and nanoparticles. Their advantages and drawbacks are dicussed.

[Plasma Metabolism and Protective Effect of Oral Administration of Niclosamide on Schistosoma japonicum Cercarial Invasion in Mice].

OBJECTIVE: To study the metabolism of niclosamide in plasma, and the protective effect of its oral administration on Schistosoma japonicum cercarial invasion in mice. METHODS: Twenty-four female Kunming mice were randomly divided into 8 groups, each with 3 mice. Each mouse was treated orally with 120 mg niclosamide per kilogram of body weight (120 mg/kg). The plasma samples were collected at 0.25, 0.5, 1, 2, 4, 8, 16, and 24 h after treatment by retro-orbital blood sampling. The blood drug concentration was determined by HPLC. The pharmacokinetics parameters were calculated such as peak concentration (Cmax), peak time (Tmax), mean residence time (MRT), and elimination half life (T½). Thirty Kunming mice were randomly divided into 6 groups. Among them, 5 groups were treated orally with 40, 80, 120, 160, and 200 mg/kg niclosamide, respectively. The remaining untreated group served as control. One hour post-treatment, each mouse was infected with 40 ± 2 Schistosoma japonicum cercariae. Another 35 mice treated with 200 mg/kg niclosamide were randomly divided into 7 groups. Mice in each group were infected with 40 ± 2 S. japonicum cercariae on 0.25, 1, 4, 8, 12, and 24 h after treatment, named as group A, B, C, D, E, and F. Five untreated mice served as control (group G). All mice were sacrificed 35 days post-infection. Mean worm burden and worm reduction were calculated. RESULTS: At a dose of 120 mg/kg niclosamide, the blood drug concentration was (0.40 ± 0.28) µg/ml at 0.25 h post-treatment, reached a peak of (0.91 ± 0.34) µg/ml at 1 h, and decreased to (0.49 ± 0.38) µg/ml at 2 h, and got close to 0 at 16 h. The mean residence time (MRT) in mice was (6.78 ± 1.47) h, and the elimination half time was (6.80 ± 7.05) h. No significant difference was found in worm burden between different dose groups and control group (P > 0.05). The mean worm burden in group A was significantly lower than that of the control (P < 0.05) with a mean worm reduction of 79.1%. And there was no significant difference in worm burden between other groups and the control (P > 0.05). CONCLUSIONS: The blood drug concentration increases rapidly by gavage administration of 120 mg/kg niclosamide, reaching to the maximum concentration at 1 h post-treatment. It shows a certain potective effect of oral administration of 200 mg/kg niclosamide on Schistosoma japonicum cercarial invasion at 0.25 h after treatment.

[Effect of long-term use of albendazole on mice liver].

OBJECTIVE: To observe the change in serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), direct bilirubin (DBL), indirect bilirubin (IBIL), albumin (ALB) and globulin (GLB), and mouse liver ultrastructure during 1-16 weeks of albendazole treatment. METHODS: 180 female Kunming mice were divided randomly into albendazole treatment group and negative control group. Each mouse of albendazole treatment group was treated with 136.3 mg/(kg x d) albendazole. The mice in control group were given same amount of physiological saline. After 1, 2, 4, 6, 8, 10, 12, 14 and 16 weeks of treatment, 10 mice from each group were randomly selected, serum samples were collected and analyzed for the above seven liver function indices. Pathological changes of liver were observed by transmission electron microscopy. Linear regression analysis was conducted for the relationship between liver function indices(dependent variable) and pathological scores (independent variable). RESULTS: During 1-16 weeks of albendazole treatment, there was no significant difference in serum levels of DBL, IBIL, ALB and GLB between albendazole treatment group and control group. Compared with other treatment period, after 12 weeks of treatment the serum levels of ALT (55.2 +/- 23.7), AST(176.4 +/- 49.2) and ALP(141.1 +/- 19.4) in albendazole treatment group were higher than that of the control (35.5 +/- 8.6, 108.2 +/- 21.9, 84.0 +/- 24.8) (P < 0.05). After 2, 8, 10, 12 and 14 weeks of treatment, the pathological score of albendazole treatment group was 11.8 +/- 4.8, 10.6 +/- 4.8, 13.6 +/- 3.5, 29.8 +/- 10.7, and 5.6 +/- 2.5, respectively, which was higher than that of the control (0.8 +/- 0.4, 1.2 +/- 0.8, 2.4 +/- 2.0, 1.2 +/- 0.4, 1.4 +/- 1.1) (P < 0.05). Among the three liver function indices AST, ALT and ALP, AST was the best fit index for linear regression. The regression formula was Y = -17.616 + 0.188X. CONCLUSION: Long-term treatment with albendazole at a dosage of 136.3 mg/(kg x d) for mice can cause significant elevation of serum levels of ALT, AST and ALP, and result in mild pathological changes in the liver.

Ultrastructural alterations of adult Schistosoma japonicum harbored in mice treated with a single oral dose of OZ78.

OBJECTIVE: To observe the ultrastructural alterations of adult Schistosoma japonicum induced by synthetic trioxolane OZ78. METHODS: Eight out of ten mice infected with 40-60 S. japonicum cercariae for 35 d were treated orally with OZ78 at a single dose of 400 mg/kg. Four groups of two mice were killed at 24 h, 3 d, 7 d, and 14 d post treatment, and schistosomes were recovered by perfusion technique, fixed, and examined by transmission electron microscopy. Schistosomes obtained from the remaining two untreated mice served as control. RESULTS: After infected mice were treated with OZ78 for 24 h, the prominent alterations in tegument of both male and female worms were observed, which revealed in flattened surface due to swelling of cytoplasmic processes, irregular expansion in distal end of cytoplasmic processes accompanied by decrease in rod-like and discoid-like secretory bodies, focal lysis of tegumental matrix; fusion of some cytoplasmic processes to form a large piece, disruption or disappearance of basal membrane, and destruction of internal structures in sensory organelles. In the subtegument, no or slight swelling and focal lysis of muscle bundles were seen, while the syncytium beneath the muscle showed enlargement of nucleus with indistinction of partial nuclear membrane, formation of small vacuoles due to focal lysis of chromatin, and emergence of degenerated mitochondria in perinuclear cytoplasm. As to parenchymal tissues, the major alterations included degeneration of mitochondria, formation of some small vacuoles and myelin-like structures. In gut epithelial cells, the prominent alterations were irregular enlargement of nucleus with light lysis of nucleoli and fusion of partial bi-layer nuclear membrane, degeneration of mitochondria in cytoplasm and collapse of microvilli. At this time point, in the vitelline cells of female worms, the most significant alteration was the collapse of many vitelline droplets, which led to release of the vitelline balls, followed by their lysis and fusion. Three to 7 d post treatment, the damage to the worms aggravated either in extent or in severity along with time. The significant damages to male and female worms were fusion of cytoplasmic processes, peeling or collapse of damaged cytoplasmic processes resulting in exposure of muscle bundles, severe destruction of sensory organelles and syncytium, focal or extensive swelling and lysis of muscle bundles, emergence of some larger piece of degenerated parenchymal tissues and severe damage to the gut epithelial cell. While in the vitelline cells of female worms, decrease in the number of vitelline droplet, focal lysis of nucleus and extensive lysis of parenchymal tissues among the vitelline cells were also observed. Fourteen days post OZ78 dosing, male and female worms which survived the treatment showed some renovation in damaged tegument and subtegument, while most gut epithelial cells and vitelline cells still revealed in prominent injury. CONCLUSION: The results demonstrate that OZ78 possesses an extensive damage to the ultrastructure in tegument and subtegument tissues including syncytium, parenchymal tissues, gut epithelial cells, and vitelline cells of adult S. japonicum.

[In vitro metabolism of fenbendazole prodrug].

Synthesized fenbendazole prodrug N-methoxycarbonyl-N'-(2-nitro-4-phenylthiophenyl) thiourea (MPT) was analyzed in vitro in artificial gastric juice, intestinal juice and mouse liver homogenate model by using HPLC method, and metabolic curve was then generated. MPT was tested against Echinococcus granulosus protoscolices in vitro. The result showed that MPT could be metabolized in the three biological media, and to the active compound fenbendazole in liver homogenate, with a metabolic rate of 7.92%. Besides, the prodrug showed a weak activity against E. granulosus protoscolices with a mortality of 45.9%.

Phylogeny-Related Variations in Venomics: A Test in a Subset of Habu Snakes (Protobothrops).

We conducted a comparative analysis to unveil the divergence among venoms from a subset of Old World habu snakes (Protobothrops) in terms of venomic profiles and toxicological and enzymatic activities. A total of 14 protein families were identified in the venoms from these habu snakes, and 11 of them were shared among these venoms. The venoms of five adult habu snakes were overwhelmingly dominated by SVMP (32.56 ± 13.94%), PLA2 (22.93 ± 9.26%), and SVSP (16.27 ± 4.79%), with a total abundance of over 65%, while the subadult P. mangshanensis had an extremely low abundance of PLA2 (1.23%) but a high abundance of CTL (51.47%), followed by SVMP (22.06%) and SVSP (10.90%). Apparent interspecific variations in lethality and enzymatic activities were also explored in habu snake venoms, but no variations in myotoxicity were found. Except for SVSP, the resemblance of the relatives within Protobothrops in other venom traits was estimated to deviate from Brownian motion evolution based on phylogenetic signals. A comparative analysis further validated that the degree of covariation between phylogeny and venom variation is evolutionarily labile and varies among clades of closely related snakes. Our findings indicate a high level of interspecific variation in the venom proteomes of habu snakes, both in the presence or absence and the relative abundance of venom protein families, and that these venoms might have evolved under a combination of adaptive and neutral mechanisms.

Further studies on mefloquine and praziquantel alone or interaction of both drugs against Schistosoma japonicum in vitro.

The aim of the present study is to further understand and analyze the interaction of mefloquine with praziquantel against adult Schistosoma japonicum in vitro. Mice infected with S. japonicum cercariae for 35-37 days were sacrificed, and adult schistosomes were collected by perfusion. Schistosomes were placed to each of 12 wells of a Falcon plate and maintained in RPMI 1640 supplemented by 10% calf serum. For determination of 50% and 95% lethal concentration (LC50 and LC95) of the two drugs in vitro, schistosomes were exposed to mefloquine at concentrations of 1, 2, 3, 4, 5, 6, 7, and 10 µg/mL or praziquantel at concentrations of 0.001, 0.01, 0.05, 0.1, 0.2, 0.5, 1, 10, and 30 µg/mL. The plate was incubated at 37°C in 95% air + 5% CO2 for 72 h. According to the half-life of oral mefloquine and praziquantel in mice, mefloquine combined with praziquantel simultaneously, mefloquine administered within 1 h after praziquantel and praziquantel administered within 17 h after mefloquine were used to evaluate the effect of mefloquine in combination with praziquantel against S. japonicum in vitro. The results showed that the LC50 and LC95 of mefloquine calculated by the Bliss method were 6.17 µg/mL (95% confidence limits, 5.84-6.517 µg/mL) and 8.703 µg/mL (95% confidence limits, 7.632-9.797 µg/mL), respectively. As to praziquantel, no worm death was seen when schistosomes were exposed to praziquantel at concentrations of 0.005-0.2 µg/mL for 72 h. While in the worms exposed to praziquantel 1, 10, and 30 µg/mL, strong spasmodic contractions of the worm body and vesiculation along the worm surface were observed, but 48-75% of the schistosomes survived the exposure in 72-h incubation. Meanwhile, the number of dead worms that emerged in each group was not proportion to the increasing concentrations. Therefore, it is not appropriate to calculate the LC50 and LC95 of praziquantel. For evaluation of the interaction with the two drugs, praziquantel 0.1 or 0.2 µg/mL, which may induce moderate or strong spasmodic contractions of the worm body and vesiculation along the worm surface, was combined with mefloquine 5, 6, or 7 µg/mL. It was found that when mefloquine combined with praziquantel simultaneously or administered 1 h after addition of praziquantel, the spasmodic contraction of the male worm body was antagonized by mefloquine in various degrees according to the concentrations of mefloquine used. Meanwhile, praziquantel-induced weakened motor activity could be reversed by mefloquine. In female worms, morphological alterations and stimulated motor activity induced by mefloquine still developed. Interestingly, using these two regimens to combine mefloquine with praziquantel resulted in no impact or a decrease in worm mortality. On the other hand, praziquantel 0.2 µg/mL administered within 17 h after mefloquine 5 or 6 µg/mL promoted the damage to the tegument of the worms, which led to enhance the worm mortality compared with that of worms exposed to mefloquine alone. The results indicate that in vitro higher concentrations of praziquantel administered within 17 h after mefloquine may increase the effect against adult schistosomes, while praziquantel combined with mefloquine simultaneously or administered 1 h before addition of mefloquine exhibits no impact or decrease in the effect against schistosomes.

Ultrastructural alterations of juvenile Schistosoma japonicum harbored in mice following mefloquine administration.

The aim of the present study was to assess the ultrastructural alterations of juvenile Schistosoma japonicum induced by mefloquine. Mice infected with 14-day-old S. japonicum were treated orally with mefloquine at a single dose of 400 mg/kg. Between 8 h and 7 days after treatment, groups of two mice were sacrificed, and schistosomula were recovered for transmission electron microscopic observations. Ultrastructural damage was seen in the tegument, subtegumental musculature, parenchymal tissues, and gut epithelial cell. It was already prominent 8 h after drug administration and increased in severity rapidly to reach a peak 3 days post-treatment. Tegumental alterations were characterized by emergence of irregular and elongated cytoplasmic processes, which further fused together accompanied by indistinction of matrix and roughness of external plasma membrane. Meanwhile, in the subtegument, damage to the syncytium, swelling, and lysis of muscle bundles and parenchymal tissues were universal, which further aggravated the lesion on the tegument, followed by collapse or disintegration of damaged tegument to form numerous fragment or debris of cytoplasmic process detached from the worm surface. Severe damage to the gut epithelial cell was also observed 8 h post-mefloquine treatment, which included focal lysis of cytoplasm accompanied by formation of vacuoles and degeneration of mitochondria, emergence of enlarged and contracted nucleus with indistinct or focal disrupted nuclear membrane, and decrease in microvilli. All these alterations further increased in severity and reached the peak 3 days post-treatment. The findings of our study indicate that mefloquine exhibits a fast and potent ability to cause extensive ultrastructural damage to juvenile S. japonicum, which correlates with its high efficacy against juvenile schistosomes.

Enhanced bioavailability and cysticidal effect of three mebendazole-oil preparations in mice infected with secondary cysts of Echinococcus granulosus.

The aim of the present study is to explore the possibility to increase the efficacy of mebendazole (MBZ) against secondary cysts of Echinococcus granulosus harbored in mice by augmenting the solubility and bioavailability of the drug. Firstly, the saturated solubility of MBZ in nine kinds of oil was determined by high performance liquid chromatography (HPLC), and MBZ was found exhibiting the highest, secondary, and lowest solubility in oleic acid (OA), glycerol trioleate (GT), and soybean oil (SB), respectively. Secondly, MBZ-OA suspension, MBZ-GT suspension, MBZ-SB suspension, and MBZ suspended in 1 % tragacanth (MBZ-1 % tragacanth) were selected for further studies on pharmacokinetics and experimental therapy in mice. Four groups of mice were treated orally with one of aforementioned four MBZ preparations at a single dose of 25 mg/kg, and concentrations of MBZ in plasma obtained from each mouse at various intervals within 24 h postadministration were determined by HPLC. The major pharmacokinetic parameters calculated by MBZ plasma concentration-time curve demonstrated that the peak concentration of the drug (C (max) ) values obtained from three MBZ-oil preparation groups was 1.6-2.8 times higher than that of MBZ-1 % tragacanth group. The same was true that the area under the drug concentration-time curve (AUC(0-∞)) values of 19.8 (2.5)-28.2 (2.5) µg/ml × h revealed in the three MBZ-oil preparation groups was significantly higher than that of 11.6 (2.0) µg/ml × h in MBZ-1 % tragacanth group, and the bioavailability of the three MBZ-oil preparation groups was 71-143 % higher than that of MBZ-1 % tragacanth group. In mice infected with secondary cysts of E. granulosus for 8 months treated orally with MBZ-1 % tragacanth at a daily dose of 25 mg/kg for 14 consecutive days, the mean cyst weight was lower than that of untreated control, but the difference was not statistically significant with cyst weight reduction of 48 %. When the infected mice received three MBZ-oil preparations at the same oral dose schedule as aforementioned, the mean cyst weights were significantly lower than those in MBZ-1 % tragacanth group or control group with cyst weight reductions of 71.2-84.7 %. The results indicate that the solubility of MBZ in oils may increase to various degrees according to the kinds of oil used. Meanwhile, three MBZ-oil (OA, GT, and SB) preparations administered orally to mice not only improve the bioavailability of MBZ relative to that of MBZ suspended in 1 % tragacanth, but their effects against hydatid cysts also significantly enhance.

[Progress on hydrolases-targeting antiparasitic prodrugs].

Prodrug strategies have been used for drug optimization to overcome the drawbacks in pharmaceutics, pharmacokinetics and pharmacodynamics. Most enzymes involved in prodrug biotransformation are hydrolases, in which esterase and amidase have been widely researched. This review summarizes the recent progress in antiparasitic prodrugs based on both targets.

Optimization of an Evaluation Method for Anti-Babesia microti Drug Efficacy.

Babesiosis is an emerging zoonotic disease that is typically caused by Babesia microti infection. Clinical treatment of B. microti infection is challenging; hence, it is crucial to find new effective drugs. The current laboratory screening methods for anti-B. microti drugs are not optimized. We conducted drug-suppressive and drug-therapeutic tests to investigate whether use of an immunosuppressant and the target gene-based qPCR are helpful to reduce the number of animals affected and to improve parasite detection in an immunocompetent mouse model. These results were verified by subpassage test. In the drug-suppressive test, no B. microti were observed after immunosuppressant administration or in subpassage mice in the 100 mg/kg robenidine hydrochloride (ROBH) group. The opposite results were observed in the control, 50 mg/kg ROBH, atovaquone (ATO) + azithromycin (AZM), and proguanil hydrochloride (PGH) groups. Significant differences were observed in the EIR and target gene relative values (both P < 0.001) between the control group and any ROBH groups. In the drug-therapeutic test, recrudescence occurred in the 50 mg/kg ROBH, ATO+AZM, and control groups. This was not observed in the 100 mg/kg ROBH group after immunosuppressant administration. Similar findings were observed in the subpassage test. This suggests that a 4-day anti-B. microti drug-suppressive test can be used in preliminary drug screening. Potentially effective drugs can be verified by immunosuppressant test in subsequent drug-therapeutic tests. Thus, a laboratory evaluation method of anti-B. microti drug efficacy was optimized, which is highly accurate and requires a short drug screening time.

Synthesis and anti-intestinal nematode activity of variously substituted benzonaphthyridine derivatives.

A series of benzonaphthyridine derivatives bearing the C=N linkage moiety were designed and synthesized. The structures of all the newly synthesized compounds were identified by elemental analysis, 1H-NMR, 13C-NMR and MS. Their anti-intestinal nematode activities against Nippostrongylus brazilliensis were evaluated in vivo by an oral route in male rats. Among these compounds, at concentrations of 10 mg/kg of rat, the compound 7-chloro-2-methoxy-10-(4-(4'-(1H-indol-5'-yl)methylene)aminophenyl)-amino-benzo[b][1,5] naphthyridine (4n) produced the highest activity, with 80.2% deparasitization. These compounds may find usefulness in the discovery and development of new anti-intestinal drugs.

Synthesis 1-acyl-3-(2'-aminophenyl) thioureas as anti-intestinal nematode prodrugs.

A series of 1-acyl-3-(2'-aminophenyl) thiourea derivatives were designed and synthesized. The structures of all the newly synthesized compounds were identified by IR, elemental analysis, ¹H-NMR and ¹³C-NMR. Their anti-intestinal nematode activities against Nippostrongylus brazilliensis were evaluated in rats by an oral route. Among these compounds, at concentrations of 10 mg/kg of rat, compound (1-(2'-furanyl)acyl-3- (2'-aminophenyl) thiourea) produced the highest activity with 89.4% deparasitization. The present work suggests that 1-acyl-3-(2'-aminophenyl) thiourea derivatives may become useful lead compounds for anti-intestinal nematode treatment.

Contribution to the echinococcosis control programme in China by NIPD-CTDR.

As a zoonotic parasitosis caused by the parasitism of Echinococcus larvae, echinococcosis imposes serious disease and economic burdens on human beings and society, and is thus a global public health issue. Its complex life history, wide distribution, the combined influence of various epidemic factors, coupled with the unique natural environment, customs, and religious beliefs in endemic areas, pose a huge challenge to the national echinococcosis control programme in China. Accurate early detection and confirmation of diagnosis of echinococcosis, the use of effective drugs, real-time surveillance of the infection status of populations and various hosts, controlling the source of infection, and blocking the route of transmission are of enormous significance for control. In this paper, the work by NIPD-CTDR on the prevention and control of echinococcosis in China is reviewed, with a view to providing reference for the further promotion of the national echinococcosis control programme.

Contributions and achievements on schistosomiasis control and elimination in China by NIPD-CTDR.

Being a zoonotic parasitic disease, schistosomiasis was widely spread in 12 provinces of Southern China in the 1950s, severly harming human health and hindering economic development. The National Institute of Parasitic Diseases at the Chinese Center for Diseases Control and Prevention, and Chinese Center for Tropical Diseases Research (NIPD-CTDR), as the only professional institution focussing on parasitic diseases at the national level, has played an important role in schistosomiasis control in the country. In this article, we look back at the changes of schistosomiasis endemicity and the contribution of NIPD-CTDR to the national schistosomiasis control programme. We review NIPD-CTDR's activities, including field investigations, design of control strategies and measures, development of diagnostics and drugs, surveillance-response of endemic situation, and monitoring & evaluation of the programme. The NIPD-CTDR has mastered the transmission status of schistosomiasis, mapped the snail distribution, and explored strategies and measures suitable for different types of endemic areas in China. With a good understanding of the life cycle of Schistosoma japonicum and transmission patterns of the disease, advanced research carried out in the NIPD-CTDR based on genomics and modern technology has made it possible to explore highly efficient and soft therapeutic drugs and molluscicides, making it possible to develop new diagnostic tools and produce vaccine candidates. In the field, epidemiological studies, updated strategies and targeted intervention measures developed by scientists from the NIPD-CTDR have contributed significantly to the national schistosomiasis control programme. This all adds up to a strong foundation for eliminating schistosomiasis in China in the near future, and recommendations have been put forward how to reach this goal.

[Research progress on the efficacy, metabolism and bioavailability of mebendazole in hydatid disease].

Mebendazole is currently used in the treatment of hydatid disease. Its poor absorption from the gastrointestinal tract and low bioavailability aroused further research on new formulations of mebendazole to increase the bioavailability and improve the therapeutic efficacy. This review summarizes the recent research progress.