Suramin could block the activity of Arabinono-1, 4-lactone oxidase enzyme from Leishmania donovani: structure-based screening and molecular dynamics analyses.

BACKGROUND: Leishmania donovani, a parasitic protozoan causing visceral leishmaniasis, can lead to a dangerous and often fatal disease in humans. Current treatment for leishmaniasis may have severe side effects, low efficacy and high cost, hence an immediate need for new efficient drugs is essential. Arabinono-1, 4-lactone oxidase enzyme from Leishmania donovani (LdALO), which catalyzes the last step of the ascorbate biosynthesis pathway, has been considered as a potential target for antileishmanial drugs design. METHODS: The current study was performed with an in silico approach to predict novel inhibitory molecules against the LdALO enzyme. Various modeling and refinement processes were employed to obtain a reliable 3D structure. RESULTS: The best LdALO model with the highest qualitative model energy analysis score was predicted by the Robetta server and subsequently refined by 3D refine and ModLoop servers. The high quality of the final LdALO model was confirmed using model assessment software. Based on docking analysis results, we predicted 10 inhibitory molecules of a US Food and Drug Administration-approved library, with appropriate criteria regarding energy binding and interaction with the main functionally active sites of LdALO, indicating that they could be significant targets for further drug design investigations against L. donovani. CONCLUSION: Suramin is used to treat the first stage of African sleeping sickness and its mechanism of action is unknown. Our results showed that suramin was the best-predicted inhibitor compound for LdALO enzyme activity.

Molecular characterization of Theileria equi infection in horse populations belonging to West Azerbaijan, Iran: insights into the importance of Equine Merozoite Antigen (EMA)-1 in its diagnosis

The major agent of equine piroplasmosis (EP), Theileria equi, contributes to significant losses in the equine industry. This study was designed to evaluate T. equi infection among horses from West Azerbaijan by microscopy and molecular approaches. One hundred and twenty six blood samples were collected from the jugular vein and placed in sterile tubes containing EDTA; these tubes were either used immediately for blood smears or stored at ­20°C for later examination by PCR. T. equi was detected in 3.2% and 27.7% of the animals examined using light microscopy and PCR methods, respectively. The prevalence of T. equi was higher in older animals (30.4%) than young equines (24.6%). Also, the females (31%) demonstrated higher T. equi infection rates than the males (23.6%). Additionally, while 12 horses housed with other animals were positive for T. equi, 23 not housed with other animals were found to be infected. No significant difference was found between infection rate and associated risk factors (age, sex, and housing with other animals). The results confirm a relatively high prevalence of T. equi in horses in the study area and also suggest that Equine Merozoite Antigen (EMA)-1 could be a strong candidate to develop diagnostic methods for T. equi infection. Due to the importance of EP in the equine industry, and the ability of animals to be lifelong carriers of T. equi, accurate and early diagnosis of the disease, based on specific antigens, is critical. Diagnosis would provide basic information about its epidemiology, distribution and prevalence, especially in apparently healthy animals, and effective control and vaccine measures.

In vitro antileishmanial activity of fisetin flavonoid via inhibition of glutathione biosynthesis and arginase activity in Leishmania infantum.

With the increasing emergence of drug resistant Leishmania sp. in recent years, combination therapy has been considered as a useful way to treat and control of Leishmaniasis. The present study was designed to evaluate the antileishmanial effects of the fisetin alone and combination of fisetin plus Meglumine antimoniate (Fi-MA) against Leishmania infantum. The IC50 values for fisetin were obtained 0.283 and 0.102 µM against promastigotes and amastigote forms, respectively. Meglumine antimoniate (MA, Glucantime) as control drug also revealed IC50 values of 0.247 and 0.105 µM for promastigotes and amastigotes of L. infantum, respectively. In order to determine the mode of action of fisetin and Meglumine antimoniate (MA, Glucantime), the activities of arginase (ARG), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) were measured. Moreover, intracellular glutathione (GSH) and nitric oxide (NO) levels in L. infantum-infected macrophages and L. infantum promastigotes which were treated with IC50 concentrations of fisetin, MA and Fi-MA were investigated. Our results showed that MA decreased CAT and SOD activity and increased NO levels in L. infantum-infected macrophages. In promastigotes, MA inhibited parasite SOD activity and reduced parasite NO production. The decreased levels of most of the antioxidant enzymes, accompanying by the raised level of NO in treated macrophages with MA, were observed to regain their normal profiles due to Fi-MA treatment. Furthermore, fisetin could prevent the growth of promastigotes by inhibition of ARG activity and reduction of GSH levels and NO production. In conclusion, these findings showed that fisetin improves MA side effects.

Prevalence of parasites and associated risk factors in domestic pigeons (Columba livia domestica) and free-range backyard chickens of Sistan region, east of Iran.

This study was carried out on free-range backyard chickens and domestic pigeons (Columba livia domestica) from December 2010 to November 2011 to determine the prevalence, intensity and species of internal and external parasites in Sistan region, east of Iran. Of the total of 59 (27 males and 32 females) free-range backyard chickens and 46 (26 males and 20 females) domestic pigeons inspected, 55 (93.22 %) and 39 (84.78 %) were infected respectively. Ten species of free-range backyard chickens parasites were collected from alimentary canals, body, head and neck, comprising of 3 species of nematodes, 4 species of cestodes and 3 species of ectoparasites as follows: Ascaridia galli (16.94 %), Heterakis gallinarum (23.72 %), Subulura brumpti (67.79 %), Raillietina tetragona (35.59 %), Raillietina echinobothrida (27.11 %), Raillietina cesticillus (15.25 %), Choanotaenia infundibulum (40.67 %), Argas persicus (16.94 %), Menopen gallinae (55.93 %) and Menacanthus stramineus (33.89 %). The domestic pigeons were infected with seven species of parasites including 2 species of nematodes, 2 species of cestodes and 3 species of ectoparasites as follows: Ascaridia colombae (15.21 %), Hadjelia truncata (17.39 %), Raillietina tetragona (26.08 %), Raillietina echinobothrida (28.26 %), Argas reflexus (13.04 %), Menopen gallinae (32.60 %), Columbicola Columba (41.30 %). This is the first survey to determine the prevalence and intensity of parasites among free-range backyard chicken and domestic pigeon species in Sistan region.