Evaluation of the non-clinical toxicity of an antiparasitic agent: diminazene aceturate.

The diminazene aceturate (C14H15N7.2C4H7NO3) is a chemotherapeutic agent with more than six decades of use, however more studies regarding its toxicity still need to be performed. Thus, the present study determined the acute toxicity (14 days) of diminazene acetate (DIZE) in male and female swiss mice by changes in body mass, food consumption, biochemical and hematological parameters, locomotor activity and motor coordination. DIZE was administered at a single dose (1000 and 2000 mg/kg) orally. In addition, in vitro antioxidant capacity, hemolytic activity, toxicity in Artemia salina and in silico evaluation were also performed. The results obtained include several signs of toxicity (hypoactivity, loss of the straightening reflex and tachycardia), reduction of behavioral activity (locomotor activity and motor coordination) and significant changes (p < 0.05) in biochemical and hematological parameters. According to the in silico study, the DIZE can be classified based on the mean lethal dose (LD50) in category 4 (300 mg/kg < LD50 ≤ 2000 mg/kg, ProTox-II) or 3 (50 mg/kg < LD50 ≤ 300 mg/kg, AdmetSAR 1.0). Additionally, DIZE (30.3-969.9 nM) was not toxic to A. salina in the first 48 hours of treatment and was not cytotoxic to rat red blood cells after induced hemolysis. In vitro results indicated low antioxidant capacity against DPPH• and ABTS•+ radicals. Therefore, DIZE induces several adverse effects with influence on the central nervous system, changes in hematological and biochemical parameters and even mortality at the highest dose. However, absence of toxicity was observed in A. salina and rats red blood cells.

Aspectos patológicos da intoxicação por aceturato de diminazeno em camelídeos sul-americanos / Pathological aspects of diminazene aceturate toxicosis in american camelids

Aceturato de diminazeno é um fármaco quimioterápico sintético comumente usado na medicina veterinária para o tratamento de doenças causadas por parasitos hematozoários. Entretanto, seu uso pode levar a efeitos colaterais, como alterações neurológicas graves e morte. A criação de camelídeos é uma atividade recente no Brasil, fazendo-se necessário conhecer mais sobre as doenças que acometem essas espécies. De dez camelídeos (seis lhamas e quatro alpacas) da propriedade, seis tiveram sinais clínicos e, destes, apenas uma lhama com manifestações leves recuperou-se. Os sinais clínicos incluíam apatia, andar cambaleante, fraqueza, sialorreia, cabeça baixa e pendida lateralmente, dificuldade em levantar e dispneia, observados a partir de 18 horas após o uso do medicamento. À necropsia e ao exame histopatológico foram observadas alterações de encefalopatia hemorrágica bilateral e simétrica, mais graves em tronco encefálico e tálamo. Este trabalho descreve as principais lesões observadas em um surto de intoxicação por diminazeno em alpacas (Lama pacos) e lhamas (Lama glama) e alerta criadores e veterinários sobre o risco de intoxicação por aceturato de diminazeno em camelídeos sul americanos.(AU)

Diminazene aceturate is a synthetic chemotherapeutic drug commonly used in veterinary medicine for the treatment of diseases caused by hematozoan parasites. However, side effects as severe neurological disorders and death can occur. The raising of american camelids is a recent activity in Brazil, requiring knowledge about diseases that affect these species, in order to avoid misguided conducts. In a herd of ten camelids (six llamas and four alpacas) six showed clinical signs and five died; only a llama with mild signs recovered. The clinical signs included apathy, difficulty to stand up, staggering gait, weakness, down head and drooping the head laterally, dyspnea and drooling of saliva, observed from 18 hours after use of the drug. At necropsy and histopathological examination was found bilateral and symmetrical hemorrhagic encephalopathy, more severe in brainstem and thalamus. This paper describes the main lesions observed in an outbreak of diminazene aceturate poisoning in alpacas (Lama pacos) and llamas (Lama glama) and alert breeders and veterinarians about the risk of poisoning by this drug in american camelids.(AU)

Nerolidol nanospheres increases its trypanocidal efficacy against Trypanosoma evansi: New approach against diminazene aceturate resistance and toxicity.

The aims of this study were to develop nerolidol-loaded nanospheres, and to evaluate their efficacy in vitro and in vivo against Trypanosoma evansi, as well as to determine their physicochemical properties, morphology, and any possible side effect in vitro against peripheral blood mononuclear cell (PBMC). The nanospheres showed an adequate particle size (149.5 nm), narrow particle distribution (0.117), negative zeta potential (-12.8 mV), and pH of 6.84, such as observed by transmission electron microscopy. In vitro, a trypanocidal effect of nerolidol and nanospheres containing nerolidol was observed at 0.5, 1.0, and 2.0%, i.e., both treatments showed a faster trypanocidal effect compared to chemotherapy (diminazene aceturate - D.A.). T. evansi infected mice were used to evaluate the effects of nerolidol-loaded nanospheres regarding pre-patent period, longevity, and therapeutic efficacy. Oral administration of nerolidol-loaded nanospheres at 1.0 mL/kg/day during 10 days increased mice survival (66.66%) compared to 0% and 33.33% of mice survival when treated with nerolidol in its free form and D.A., respectively. Cytotoxic study indicated that both treatments showed no side effects in vitro against PBMC, an important marker used in toxicological surveys. Therefore, nanoencapsulation increased the therapeutic efficacy of nerolidol against T. evansi, and can be used as an alternative treatment for T. evansi infection.

Effects of treatment with the anti-parasitic drug diminazene aceturate on antioxidant enzymes in rat liver and kidney.

Diminazene aceturate (DA) is the active component of some trypanocidal drugs used for the treatment of animals infected with trypanosomosis and babesiosis. Residues of DA may cause hepatotoxic and nephrotoxic effects. Therefore, the purpose of this study was to investigate the occurrence of oxidative stress, i.e., changes in the antioxidant defense system of rats treated with a single dose of 3.5 mg kg(-1) of DA. All treatments were intramuscularly administered, and evaluations were performed on days 7 and 21 post-treatment (PT). Liver and kidney samples were collected and evaluated by histopathology and oxidative stress parameters (thiobarbituric acid-reactive species, catalase, superoxide dismutase, carbonyl, non-protein thiols, and reduced glutathione). Finally, blood was collected to determine seric DA concentration. Superoxide dismutase (SOD) and catalase (CAT) activities in liver and kidney of rats were dramatically inhibited (p < 0.05) compared to the control group on day 21 PT. This difference is related to the concomitant increase (p < 0.05) in malondialdehyde (MDA) content, which was identified by an increase in thiobarbituric acid-reactive species (TBARS) levels. The carbonyl levels did not differ between groups (p > 0.05). Both non-protein thiols (NPSH) and glutathione (GSH) levels in liver and kidney decreased (p < 0.05) on day 21 PT. Chromatographic analyses showed lower levels of DA on day 21 PT compared to day 7 PT. A negative correlation was observed between DA concentration in serum and lipid peroxidation in liver and kidney tissues on 21 days PT. Histopathology revealed vacuolar degeneration in liver and kidney samples on day 21 PT. Our findings indicate that DA could cause oxidative damage to liver and kidney of rats.

Diminazene aceturate liposomes: morphometric and biochemical liver, kidney, and spleen of rats infected with Trypanosoma evansi.

The aim of this study was to evaluate the effect of treatment with liposomal (L-DMZ) and conventional (C-DMZ) diminazene aceturate formulations on hepatic and renal functions of rats, experimentally infected with Trypanosoma evansi. For this purpose, 72 Wistar rats (Rattus norvegicus) were divided into six groups (A, B, C, D, E, and F). Each group was subdivided into two other subgroups in order to assess the biochemical and histological results on days 7 and 40 post-treatment (PT). Treatments were carried out based on two different therapeutic protocols: L-DMZ and C-DMZ at 3.5mg/kg(-1), single dose (groups C and D), and five successive doses within intervals of 24h (groups E and F). Groups A and B corresponded to uninfected and infected (without treatment) animals, respectively. Sample collections were held on days 7 and 40 PT for the assessment of hepatic [alkaline phosphatase (AP), alanine transferase (ALT), albumin, gamma glutamil transferase (GGT) and renal functions (creatinine and urea). Additionally, the histology of fragments of liver, kidney, and spleen was performed. Animals in group B showed a significant increase in AP, GGT, ALT, and urea when compared with group A. On day 7 post-inoculation (PI), the biochemical analysis showed a reduction (P<0.05) of AP and GGT, while the levels of urea were increased in groups C, D, E, F. On day 40 PT, ALT was increased in these same groups when compared with group A. In histopathology, changes in liver samples were observed on day 7 PT in groups D and F, especially regarding the area and density of the hepatocytes. Renal analysis exhibited changes in glomerular space, glomerular, and corpuscular areas in group E. Therefore, these results allowed us to conclude that the treatment with L-DMZ and C-DMZ led to variable biochemical changes, which defined the functions of the liver and kidneys of treated animals, since the main histopathology alterations were observed in animals treated with liposomes, at their higher dosages. Thus, treatments with L-DMZ and C-DMZ in five consecutive doses were effective although being followed by liver toxicity.

Diminazene aceturate (Berenil) modulates LPS induced pro-inflammatory cytokine production by inhibiting phosphorylation of MAPKs and STAT proteins.

Although diminazene aceturate (Berenil) is widely used as a trypanolytic agent in livestock, its mechanisms of action remain poorly understood. We previously showed that Berenil treatment suppresses pro-inflammatory cytokine production by splenic and liver macrophages leading to a concomitant reduction in serum cytokine levels in mice infected with Trypanosoma congolense or challenged with LPS. Here, we investigated the molecular mechanisms through which Berenil alters pro-inflammatory cytokine production by macrophages. We show that pre-treatment of macrophages with Berenil dramatically suppressed IL-6, IL-12 and TNF-α production following LPS, CpG and Poly I:C stimulation without altering the expression of TLRs. Instead, it significantly down-regulated phosphorylation of mitogen-activated protein kinases (p38, extracellular signal-regulated kinase and c-Jun N-terminal kinases), signal transducer and activator of transcription (STAT) proteins (STAT1 and STAT3) and NF-кB p65 activity both in vitro and in vivo. Interestingly, Berenil treatment up-regulated the phosphorylation of STAT5 and the expression of suppressor of cytokine signaling 1 (SOCS1) and SOCS3, which are negative regulators of innate immune responses, including MAPKs and STATs. Collectively, these results show that Berenil down-regulates macrophage pro-inflammatory cytokine production by inhibiting key signaling pathways associated with cytokine production and suggest that this drug may be used to treat conditions caused by excessive production of inflammatory cytokines.

In vitro activity and preliminary toxicity of various diamidine compounds against Trypanosoma evansi.

Trypanosoma evansi is an animal pathogenic protozoan, causing a wasting disease called Surra, which is broadly distributed in a wide range of mammalian hosts. Chemotherapy is the most efficient control method, which depends on four drugs. Unfortunately, with the appearance of resistance to these drugs, their effective use is threatened, emphasising a need to find new drugs. Diamidines bind to the minor groove of DNA at AT-rich sites and exert their anti-trypanosomal activity by inhibiting one or more DNA dependent enzymes or by directly impeding the transcription process. In total, 67 novel diamidine compounds were tested in vitro to determine activity against an animal pathogenic Chinese kinetoplastic T. evansi strain. In comparison, a human pathogenic Trypanosoma brucei rhodesiense strain and a P2 transporter knock out of a Trypanosoma brucei brucei strain were also tested. All diamidine compounds tested in this study against T. evansi produced inhibitory concentration (IC(50)) values below 50 nM. The results demonstrate that these compounds are highly active against T. evansi in vitro. In addition, preliminary in vivo toxicity tests were performed on all 67 diamidines with 69% of the compounds showing no acute toxicity at an intra-peritoneal dose of 100mg/kg.

Micronuclei induced by aneugens and clastogens in mononucleate and binucleate cells using the cytokinesis block assay.

The human in vitro micronucleus (MN) test has become a fast and reliable assay for mutagenicity testing. Currently, this assay is mostly performed with cytochalasin B, which prevents cytokinesis, resulting in polynucleated cells. The number of nuclei per cell indicates the number of nuclear divisions that have occurred since the addition of cytochalasin B. It is recommended that MN are only counted in binucleated lymphocytes, because these cells have finished one nuclear division. Therefore, almost no attention has been paid to MN in mononucleated cells. However, recent studies have indicated that aneugens, but not clastogens, also induce MN in mononucleates. In order to evaluate mononucleates to distinguish between aneugenic and clastogenic effects, we tested some typical aneugens and clastogens in whole blood lymphocyte cultures of four donors with the cytokinesis block micronucleus (CBMN) assay. Results showed that the aneugens diethylstilbestrol (80 microM), griseofulvin (25 microg/ml) and vincristine sulphate (15 microg/ml) increased MN frequencies in mononucleated and binucleated cells, whilst the clastogens mitomycin C (500 ng/ml), bleomycin (6 microg/ml) and doxorubicin (20 microg/ml) increased MN frequency only in binucleates. We also tested the Y heterochromatin decondensing drug berenil (300 microg/ml). Berenil induced an extremely high number of MN in mononucleated as well as in binucleated cells, indicating an aneugenic action. This was confirmed by centromere labelling. The results suggest that MN in mononucleates may be an interesting additional parameter in the CBMN assay. Future studies should clarify whether the micronucleated mononucleate cells have escaped the cytokinesis block and become polyploid.

Lipid-drug conjugate nanoparticles of the hydrophilic drug diminazene-cytotoxicity testing and mouse serum adsorption.

Sleeping sickness is a widely distributed disease in great parts of Africa. It is caused by Trypanosoma brucei gambiense and rhodiense, transmitted by the Tse-Tse fly. After a hemolymphatic stage, the parasites enter the central nervous system where they cannot be reached by hydrophilic drugs. To potentially deliver the hydrophilic antitrypanosomal drug diminazene diaceturate to the brain of infected mice, the drug was formulated as lipid-drug conjugate (LDC) nanoparticles (NP) by combination with stearic- (SA) and oleic acid (OA). To estimate the in vivo compatibility, the particles were incubated with human granulocytes. Because as potential delivery mechanism the absorption of specific serum proteins (ApoE, Apo AI and Apo AIV) was found to be responsible for the delivery of nanoparticles to the brain, demonstrated using PBCA nanoparticles coated with polysorbate 80 (LDL uptake mechanism) the nanoparticles were incubated with mouse serum and the adsorption pattern was determined using the 2-D PAGE technique. As a result of this study, the cytotoxic potential was shown to decrease when diminazene is part of the particle matrix compared to pure fatty acid nanoparticles and the mouse serum protein adsorption pattern differs from the samples studied earlier in human serum. Especially, the fact concerning Apo-E that could be detected when the particles were incubated in human serum is absent after the mouse serum incubation, potentially, is a critical point for the delivery via the LDL-uptake mechanism but the data demonstrate that LDC nanoparticles, with 33% (wt/wt) drug loading capacity possess the potential to act as a delivery system for hydrophilic drugs like diminazene diaceturate and that further studies have to demonstrate the usability as a brain delivery system.

Cytokines and the acute phase response in post-treatment reactive encephalopathy of Trypanosoma brucei brucei infected mice.

Stimulation of the acute phase response during infection of mice with Trypanosoma brucei brucei (T. b. brucei) was investigated in an experimental model of the post-treatment reactive encephalopathy (PTRE), a common side-effect of anti-trypanosome therapy. Plasma levels of the acute phase proteins (APP), haptoglobin (Hp) and serum amyloid P (SAP) increased by day 7 post-infection, but by day 20 had fallen to an intermediate level. This was accompanied by induction of the cytokines, interleukin (IL)-6 and tumour necrosis factor-alpha (TNFalpha) in both liver and brain. Treatment of mice on day 21 with a subcurative dose of diminazene aceturate (Berenil), a procedure known to induce a mild PTRE, cleared the parasite from the circulation with plasma APP and liver expression of mRNA for IL-6 and TNFalpha returning to the levels in the controls. Cytokine mRNA for both IL-6 and TNFalpha was detected in the brains of animals with developing PTRE although TNFalpha was not significantly greater than in the control group. A further subcurative dose of Berenil, leading to a more severe PTRE, was associated with elevated serum concentrations of Hp and SAP, increased TNFalpha mRNA in the liver and detectable IL-6 and TNFalpha mRNA in the brain. mRNA for IL-1alpha was expressed in brain and liver samples from all animals. A severe PTRE caused a systemic acute phase response which was not apparent with a mild PTRE. The pattern of cytokine mRNA induction was similar following both drug treatments. However, the difference in APP production could be caused by a breakdown in the blood-brain barrier during severe PTRE allowing cytokine synthesised in the brain to enter the circulation and maintain a systemic response.

Trypanocidal resistance in Trypanosoma evansi in vitro: effects of verapamil, cyproheptidine, desipramine and chlorpromazine alone and in combination with trypanocides.

A study was conducted in vitro to assess the ability of calcium antagonists to reverse trypanocidal resistance in Trypanosoma evansi. Susceptibility patterns of sensitive and resistant parasites were evaluated against calcium antagonists of several chemical classes (verapamil, cyproheptidine, desipramine and chlopromazine), alone and in combination with suramin, diminazene aceturate or melarsen oxide cyteamine. The putative resistance modulators were intrinsically antitrypanosomal, but were unable to reverse resistance to any of the trypanocides tested. It was thus concluded that resistance to these trypanocides in T. evansi may differ from drug resistance mechanisms occurring in cancer cells, malaria or in South American trypanosomosis, where calcium antagonists have successfully reversed resistance.

Resistance to diminazine aceturate by Trypanosoma congolense from cattle in the Zambezi Valley of Zimbabwe.

The susceptibility of 14 stocks of Trypanosoma congolense, recently isolated from cattle, to therapeutic doses of diminazene aceturate and to isometamidium chloride was assessed in laboratory mice. Eight isolates were readily susceptible to the normal therapeutic dose of diminazene, two were resistant to the drug at 14 mg kg-1, and four were totally resistant at 28 mg kg-1. All the isolates were susceptible to isometamidium chloride at 0.5 mg kg-1. These observations highlight the need for regular evaluation of drugs used in the control of trypanosomosis.

Teratological assessment of the antiprotozoal, diminazene diaceturate, in rats.

Diminazene diaceturate was dissolved in deionized water and administered to pregnant rats by oral gavage once daily on days 8-15 of pregnancy at dose levels of 0, 100, 250, 500 and 1000 mg/kg. On day 21 of pregnancy, the dams were killed and the number of implants, resorptions and live fetuses counted. All fetuses were examined by routine teratological method. A significant increase in fetal resorptions and decrease in fetal body weights were found at the 1000 mg/kg dose. No significant increase in the incidence of anomalous fetuses was observed in external, skeletal and internal examinations even at the maternally toxic dose of 1000 mg/kg. Thus, these data indicate that diminazene diaceturate is not teratogenic in rats.

Biochemical and genetic analysis of toxic effect of HOE 15030 in mammalian cells.

HOE 15030 inhibited the growth of BHK cells at concentrations that did not inhibit their nuclear DNA and RNA syntheses. When BHK cells were cultured in the presence of 30 micrograms/ml of HOE 15030, cells were arrested in the G1 phase after one or two cell divisions. After removal of the drug, cells progressed through the G1 to the S phase. HOE 15030 inhibited the activities of both topoisomerases I and II in vitro. To determine the target molecule of HOE 15030 in cells, we isolated a HOE 15030-resistant (HOEr) mutant of BHK cells. The HOEr cells exhibited cross-resistance to ethidium bromide, acriflavine, and rhodamine 123, and slight cross-resistance to 4'-dimethylepipodophyllotoxin-4-(4,6-O-ethylidine-beta-D-glu copyranoside) (VP-16) and adriamycin, but not to chloramphenicol, oligomycin, novobiocin, colchicine, or vinblastine. The uptake and retention of rhodamine 123 by HOEr cells were lower than those by BHK cells. Mitochondrial DNA synthesis of HOEr cells was more resistant to HOE 15030 and ethidium bromide than that of wild-type cells. These results indicate that the resistance of HOEr cells to drugs is due to reduced uptake or accumulation of the drugs by mitochondria and suggest that the mitochondria are the main target of HOE 15030 in cells.

Comparative studies of the effects of quinuronium sulfate and diminazene diaceturate in sheep.

Biochemical parameters in 20 sheep were investigated following administration of quinuronium sulfate or diminazene diaceturate. The usual signs of salivation, micturition, anorexia, depression, muscular tremors and ataxia were observed within 20 min in sheep receiving therapeutic and double doses of quinuronium sulfate. There was an increased dose dependent plasma LDH activity above baseline values following administration of quinuronium sulfate and a non-dose dependent increased trend in diminazene diaceturate treatment. Plasma CK activity had an increased trend (p less than 0.05) above baseline values following administration of the two babesicides. Plasma BUN levels increased significantly (p less than 0.05) following administration of the two drugs. This study indicated that quinuronium sulfate is more organotoxic and hypotensive than diminazene diaceturate at therapeutic and/or above therapeutic dosages.