Susceptibility of Leishmania to novel pentavalent organometallics: Investigating impact on DNA and membrane integrity in antimony(III)-sensitive and -resistant strains.

The aim the present study was to investigate the impact of novel pentavalent organobismuth and organoantimony complexes on membrane integrity and their interaction with DNA, activity against Sb(III)-sensitive and -resistant Leishmania strains and toxicity in mammalian peritoneal macrophages. Ph3M(L)2 type complexes were synthesized, where M = Sb(V) or Bi(V) and L = deprotonated 3-(dimethylamino)benzoic acid or 2-acetylbenzoic acid. Both organobismuth(V) and organoantimony(V) complexes exhibited efficacy at micromolar concentrations against Leishmania amazonensis and L. infantum but only the later ones demonstrated biocompatibility. Ph3Sb(L1)2 and Ph3Bi(L1)2 demonstrated distinct susceptibility profiles compared to inorganic Sb(III)-resistant strains of MRPA-overexpressing L. amazonensis and AQP1-mutated L. guyanensis. These complexes were able to permeate the cell membrane and interact with the Leishmania DNA, suggesting that this effect may contribute to the parasite growth inhibition via apoptosis. Taken altogether, our data substantiate the notion of a distinct mechanism of uptake pathway and action in Leishmania for these organometallic complexes, distinguishing them from the conventional inorganic antimonial drugs.

Biomedical Applications of Green Synthesized Zinc Oxide and Magnesium-Doped Zinc Oxide Nanoparticles Using Aqueous Extract of Ziziphus Oxyphylla Leaves.

Zinc oxide (ZnO) and magnesium-doped zinc oxide (Mg-doped ZnO) nanoparticles (NPs) were synthesized using Ziziphus oxyphylla's aqueous leaf extract as reducing agent. UV-Vis absorption peaks at 324 nm and 335 nm were indicative of ZnO and Mg-doped ZnO, respectively. FTIR absorption bands observed at 3238, 1043, 1400, 1401, 2186 and 2320 cm-1 suggested the presence of phenols, alcohols, saturated hydrocarbons, and possibly alkynes. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy revealed pure, spherical and agglomerated NPs with average size of 35.9 nm (ZnO) and 56.8 nm (Mg-doped ZnO). Both NPs remained active against all bacterial strains with the highest inhibition zones observed against Proteus vulgaris (21.16±1.25 mm for ZnO and 24.1±0.76 mm for Mg-doped ZnO. EtBr fluorescence (cartwheel assay) indicated efflux pump blockage, suggesting its facilitation in the bacterial growth inhibition. Antioxidant potential, determined via DPPH radical scavenging assay, revealed stronger antioxidant potential for Mg-doped ZnO (IC50 21.53±0.76 µg/mL) than pure ZnO (IC50 30.32±0.73 µg/mL). Furthermore, both NPs showed antileishmanial activity against Leishmania tropica promastigotes (IC50 47.23±3.22 µg/mL for Mg-doped ZnO and 64.34±6.56 for ZnO), while neither NP exhibited significant hemolysis, indicating biocompatibility and further assessment for their drugability.

Comparative analysis of the severity and progression of cutaneous leishmaniasis caused by Leishmania tropica in untreated and glucantime-treated patients.

Millions of people worldwide are affected by cutaneous leishmaniasis (CL), a disease that has a significant impact on morbidity and mortality. Understanding the immune responses responsible for tissue damage or the process of lesion healing plays a pivotal role in shaping optimal treatment strategies. In this study, we investigated immunological phenotypes for three groups: glucantime treated (n = 30) and untreated (n = 30) CL patients infected with Leishmania tropica (L. tropica), and healthy controls (n = 20). T-lymphocytes (CD4+ and CD8+), and B lymphocytes (CD14+ and CD19+) were isolated using antibody-conjugated microbeads and magnetic field isolation to achieve high purity. A higher significant difference was observed between T-lymphocytes (CD4+ and CD8+), and B-lymphocytes (CD14+ and CD19+) cells in CL-infected groups before and after treatment (p < 0.0001). When compared, there was also a significant difference among T-lymphocytes (CD4+ and CD8+), B lymphocytes (CD14+ and CD19+) p < 0.0001, p < 0.0005, and p < 0.0007, respectively between CL-infected individuals (before and after treatment) to controls. Our findings suggest that an increased proportion of these cells seen in treated patients may mediate healing, while it is also possible that they may contribute to tissue injury. Understanding the immune system and lesion size of CL can help develop immunotherapies and comprehend the evolution of this parasitic disease.

Cholesterol improves stability of amphotericin B nanoemulsion: promising use in the treatment of cutaneous leishmaniasis.

Aim: Amphotericin B (AmB) is an antileishmanial drug with high toxicity; however, this drawback might overcome by decreasing the AmB self-aggregation state. This work aimed at evaluating the influence of cholesterol on the aggregation state of AmB loaded in a nanoemulsion (NE-AmB) for the treatment of cutaneous leishmaniasis. NE-AmB (1, 4 and 8 mg/kg/day) was administered intravenously to animals infected by Leishmania major every 2 days for a total of five injections. Results: Ultraviolet-visible spectroscopy and circular dichroism studies demonstrated that cholesterol reduced AmB aggregation state in NE. NE-AmB was stable after 180 days, and its hemolytic toxicity was lower than that observed for the conventional AmB. NE-AmB administered intravenously into animals infected by Leishmania major at 8 mg/kg was capable of stabilizing the lesion size and reducing the parasitic load. Conclusion: These findings support the NE potential as a stable nanocarrier for AmB in the treatment of cutaneous leishmaniasis.

Multiparametric approach to assess the disease severity and progression of cutaneous leishmaniasis infection.

The pathophysiology of Cutaneous Leishmaniasis (CL), an infection caused by Leishmania tropica (L. tropica) and Leishmania major (L. major) is primarily determined by inflammation-mediated immune cells. The immune response mainly depends on cells and molecules related to T-cells that influence susceptibility and disease development. Understanding the immunological mechanisms that cause tissue injury or lesion healing is critical for developing appropriate treatment strategies. In the present study, T-cells profile and cell-free mitochondrial DNA (CF mt-DNA) were investigated in CL patients infected with L. tropica (n = 34) and L. major (n = 2) and compared with non-infected healthy controls (n = 20). There was a significant (p<0.0001) difference between CD4+ T-cells among L. tropica and L. major CL-infected groups as compared to control while no significant difference (p = 0.8597) was found in the percentages of CD8+ T-cells. When L. tropica and L. major CL-infected individuals were compared to controls, the levels of IL-4 and expression of CF mt-DNA were significantly higher (p<0.0001). Higher levels of CF mt-DNA were detected in CL patients, irrespective of the infective Leishmania species. We proposed that the levels of CF mt-DNA and IL-4 in CL-infected individuals can be used to determine the disease progression. A better understanding of these biomarkers and evaluation of the immune responses in CL patients might benefit the development of vaccines and immunotherapies.

Novel coumarin-isatin hybrids as potent antileishmanial agents: Synthesis, in silico and in vitro evaluations.

Leishmaniasis being one of the six major tropical diseases that affects nearly 0.7-1.3 million people annually, has so far limited and high toxic therapeutic options. Herein, we report the synthesis, in silico, and in vitro evaluations of novel coumarin-incorporated isatin hydrazones (Spf-1 - Spf-10) as highly potent and safe antileishmanial agents. Molecular docking was initially carried out to decipher the binding confirmation of lead molecules towards the active cavity of the target protein (Leishmanolysin gp63) of Leishmania tropica. Among all the docked compounds, only Spf-6, Spf-8, and Spf-10 showed high binding affinities due to a pattern of strong conventional hydrogen bonds and hydrophobic π-interactions. The molecular dynamics simulations showed the stable pattern of such bonding and structure-based confirmation with a time scale of 50 ns towards the top compound (Spf-10) and protein. These analyses affirmed the high stability of the system. Three out of ten compounds evaluated for their antileishmanial activity against Leishmania tropica promastigotes and amastigotes were found to be active at micromolar concentrations (IC50 range 0.1-4.13 µmol/L), and most importantly, they were also found to be highly biocompatible when screened for their toxicity in human erythrocytes.

Reactive oxygen species generating photosynthesized ferromagnetic iron oxide nanorods as promising antileishmanial agent.

Aim: To investigate the photodynamic therapeutic potential of ferromagnetic iron oxide nanorods (FIONs), using Trigonella foenum-graecum as a reducing agent, against Leishmania tropica. Materials & methods: FIONs were characterized using ultraviolet visible spectroscopy, x-ray diffraction and scanning electron microscopy. Results: FIONs showed excellent activity against L. tropica promastigotes and amastigotes (IC50 0.036 ± 0.003 and 0.072 ± 0.001 µg/ml, respectively) upon 15 min pre-incubation light-emitting diode light (84 lm/W) exposure, resulting in reactive oxygen species generation and induction of cell death via apoptosis. FIONs were found to be highly biocompatible with human erythrocytes (LD50 779 ± 21 µg/ml) and significantly selective (selectivity index >1000) against murine peritoneal macrophages (CC50 102.7 ± 2.9 µg/ml). Conclusion: Due to their noteworthy in vitro antileishmanial properties, FIONs should be further investigated in an in vivo model of the disease.

Combination oral therapy against Leishmania amazonensis infection in BALB/c mice using nanoassemblies made from amphiphilic antimony(V) complex incorporating miltefosine.

Clinically available drugs for mucocutaneous and cutaneous leishmaniases (CL) include mainly pentavalent antimony (Sb(V)) complexes, liposomal amphotericin B, and miltefosine (HePC). However, they present at least one of the following limitations: long-term parenteral administration through repeated doses, severe side effects, drug resistance, and high cost. HePC is the only oral drug available, but the appearance of resistance has resulted in changes of its use from monotherapy to combination therapy. Amphiphilic Sb(V) complexes, such as SbL8 obtained from reaction of Sb(V) with N-octanoyl-N-methylglucamide, were recently found to be orally active against experimental CL. The property of SbL8 to self-assemble in aqueous solution, forming nanostructures, led us to investigate the incorporation of HePC into SbL8 nanoassemblies and the therapeutic efficacy of SbL8/HePC nanoformulation by oral route in a murine model of CL. HePC incorporation into the SbL8 nanosystem was evidenced by using a fluorescent analog of HePC. The antileishmanial activity of SbL8/HePC nanoassemblies was evaluated after daily oral administration for 30 days in Leishmania amazonensis-infected BALB/c mice, in comparison with monotherapies (SbL8 or HePC) and saline control. All the treatments resulted in significant reduction in the lesion size growth, when compared with control. Strikingly, only SbL8/HePC nanoassemblies promoted a significant decrease of the parasite burden in the lesion. This work establishes the therapeutic benefit of SbL8/HePC association by oral route in a CL model and constitutes an important step towards the development of new orally active drug combination.

Comprehensive investigations on anti-leishmanial potentials of Euphorbia wallichii root extract and its effects on membrane permeability and apoptosis.

Clinically available synthetic chemotherapeutics to treat the vector-borne protozoan infection, leishmaniasis, are associated with serious complications such as toxicity and emergence of resistance. Natural products from plants consist of interesting biomolecules that may interfere with DNA or membrane integrity of the parasite and can possibly minimise the associated side effects. In the present study, various fractions of Euphorbia wallichii (EW) root extracts including n-hexane (EWNX), ethyl acetate (EWEA), chloroform (EWCH) and aqueous (EWAQ), were evaluated for their antileishmanial potential against Leishmania tropica followed by investigation of the possible mechanism of action via reactive oxygen species (ROS) quantification, membrane permeability (via sytox green dye) and apoptotic assay (via AO/EB method) using fluorescent microscopy. Two of the fractions i.e. EWEA and EWAQ inhibited the growth of promastigotes (IC50 7.8 and 10.2 µg/mL, respectively) and amastigotes (IC50 9.9 and 13.3 µg/mL, respectively) forms almost at similar concentrations as found for the standard antileishmanial drugs, tartar emetic (TA) and Glucantime (IC50 9.4 and 21.5 µg/mL, respectively). Both the active fractions remained non-toxic towards human blood erythrocytes and were able to cause membrane permeability and apoptotic induction (using Triton X-100 as a positive control) leading to death of Leishmania parasites. However, both the fractions could not triger significant and persistent ROS generation, compared to hydrogen peroxide used as a positive control. Antilesihmanial activity of the two active fractions might be attributed to the presence of high quantity of tannins and saponins.

Comprehensive investigation on the synergistic antibacterial activities of Jatropha curcas pressed cake and seed oil in combination with antibiotics.

Synergistic combinations of various antimicrobial agents are considered ideal strategies in combating clinical and multidrug resistant (MDR) infections. In this study, antibacterial potential of Jatropha curcas crude seed extracts, seed oil, commercially available antibiotics, and their combinations were investigated for their synergistic effect against clinical, MDR and ATCC bacterial strains by agar well diffusion assay. Methanolic extracts remained more active against Staphylococcus aureus (ATCC), with zone of inhibition (ZOI) of 21 mm, than clinical and methicillin-resistant S. aureus (MRSA) strains (ZOI range ~ 15.0-17.0 mm). Molecular docking demonstrated that beta-monolaurin from methanolic extract exhibited greater affinity conformation for UDP-N-acetylmuramoyl-tripeptide-D-alanyl-D-alanine (MurF) ligase's active pocket with binding energy of -7.3 kcal/mol. Moxifloxacin exhibited greater activity against Escherichia coli (ATCC) (ZOI ~ 50.0 mm), followed by ofloxacin against Pseudomonas chlororaphis (47.3 mm), moxifloxacin against P. monteilii (47 mm), P. aeruginosa (46.3 mm) and MRSA2 (46 mm) and ofloxacin against S. aureus (ATCC) strains (45.7 mm). Methanolic extract in combination with rifampicin showed the highest synergism against MRSA strains, A. baumannii, E. coli, E. faecalis, S. aureus, and P. aeruginosa, A. baumannii (MDR strain), P. chlororaphis, E. coli ATCC25922 and S. aureus ATCC25923. In combinations, moxifloxacin exhibited the highest antagonism. The methanolic, n-hexane, aqueous extracts and seed oil in various combinations with antibiotics showed 44.71, 32.94, 9.41 and 25.88% synergism, respectively. The current study showed that potency of antibiotics was improved when screened in combination with J. curcas seed's components, supporting the drug combination strategy to combat antibacterial resistance.

Efficacy of Meglumine Antimoniate in a Low Polymerization State Orally Administered in a Murine Model of Visceral Leishmaniasis.

Progress toward the improvement of meglumine antimoniate (MA), commercially known as Glucantime, a highly effective but also toxic antileishmanial drug, has been hindered by the lack of knowledge and control of its chemical composition. Here, MA was manipulated chemically with the aim of achieving an orally effective drug. MA compounds were synthesized from either antimony pentachloride (MA-SbCl5) or potassium hexahydroxyantimonate [MA-KSb(OH)6] and prepared under a low polymerization state. These compounds were compared to Glucantime regarding chemical composition, permeation properties across a cellulose membrane and Caco-2 cell monolayer, and uptake by peritoneal macrophages. MA-SbCl5 and MA-KSb(OH)6 were characterized as less polymerized and more permeative 2:2 Sb-meglumine complexes than Glucantime, which consisted of a mixture of 2:3 and 3:3 Sb-meglumine complexes. The antileishmanial activities and hepatic uptake of all compounds were evaluated after oral administration in BALB/c mice infected with Leishmania infantum chagasi, as a model of visceral leishmaniasis (VL). The synthetic MA compounds given at 300 mg Sb/kg of body weight/12 h for 30 days significantly reduced spleen and liver parasite burdens, in contrast to those for Glucantime at the same dose. The greater activity of synthetic compounds could be attributed to their higher intestinal absorption and accumulation efficiency in the liver. MA-SbCl5 given orally was as efficacious as Glucantime by the parenteral route (80 mg Sb/kg/24 h intraperitoneally). These data taken together suggest that treatment with a less-polymerized form of MA by the oral route may be effective for the treatment of VL.

Plants as Antileishmanial Agents: Current Scenario.

Leishmaniasis is a clinical manifestation caused by the parasites of the genus Leishmania. Plants are reservoirs of bioactive compounds, which are known to be chemically balanced, effective and least injurious as compared with synthetic medicines. The current resistance and the toxic effects of the available drugs have brought the trend to assess the antileishmanial effect of various plant extracts and their purified compound/s, which are summarized in this review. Moreover, it also highlights various traditional remedies used by local healers against leishmaniasis. A systematic cross-sectional study for antileishmanial activity of natural products was carried out using multiple literature databases. The records retrieved since 2000 till year 2016 were analysed and summarized in the form of comprehensive tables and graphs. Natural products are potential source of new and selective agents that can significantly contribute to primary healthcare and probably are promising substitutes of chemicals for the treatment of protozoan diseases like leishmaniasis. Where the researchers prefer to use alcoholic solvents for the extraction of antileishmanial agents from plants, most of the studies are limited to in vitro conditions majorly on using promastigote forms of Leishmania. Thus, there is a need to carry out such activities in vivo and in host macrophages. Further, there is a need of mechanistic studies that can help taking few of the promising pure compounds to clinical level. Copyright © 2016 John Wiley & Sons, Ltd.

Cytotoxicity and apoptotic activity of novel organobismuth(V) and organoantimony(V) complexes in different cancer cell lines.

Novel organobismuth(V) and organoantimony(V) complexes of Ph3ML2 type were synthesized, in which L = deprotonated 2-acetylbenzoic acid (2AcBH), 4-acetylbenzoic acid (4AcBH) or 5-acetylsalicylic acid (5AcSH) and M = bismuth(V) or antimony(V). Complexes [Ph3Bi(2AcB)2] (1) [Ph3Sb(4AcB)2] (2), [Ph3Bi(4AcB)2] (3) and [Ph3Sb(5AcS)2(.)CHCl3] (4) were characterized by elemental analysis, IR, and NMR. Crystal structures of 2 and 4 were determined by single crystal X-ray diffraction. In vitro cytotoxic activities against cancerous (human chronic myelogenous leukemia, K562 and murine metastatic melanoma, B16F10) and healthy non-cancerous (murine fibroblasts, L929 and murine melanocytes, Melan-A) cells showed that, compared to free ligands, both of the metal complexes are more active as anticancer agents at low concentration in cancerous cell lines, but also possessed toxic effect at comparatively higher concentration towards the non-cancerous cells. The organobismuth(V) complex Ph3Bi(2AcB)2 was found to be more active than the Ph3BiCl2 metal precursor against the tumor cell lines and exhibited the highest selectivity index. Moreover, evaluation of the pro-apoptotic activity of Ph3Bi(2AcB)2 in B16F10 cells, by quantifying the cellular DNA using flow cytometry, indicates that cell cycle arrest and cell apoptosis contribute to the drug cytotoxicity. This work supports the great potential of organobismuth(V) dicarboxylate complexes as anticancer agents.

Mixed antimony(V) complexes with different sugars to modulate the oral bioavailability of pentavalent antimonial drugs.

Previous studies have shown that the association of the drug meglumine antimoniate (MA) with ß-cyclodextrin can improve its bioavailability by the oral route. In this work, ribose and maltose were investigated for their ability to form mixed or association complexes with MA, release MA and modulate the serum levels of Sb after oral administration in mice. Analysis of the MA/ribose composition by high performance liquid chromatography coupled to mass spectrometry (LCMS-IT-TOF) revealed the presence of mixed meglumine-Sb-ribose and Sb-ribose complexes. Analysis of the MA/maltose composition suggested the formation of MA-maltose association compounds. Circular dichroism characterization of these compositions following dilution in water at 37 °C suggested a partial and slow dissociation of the association compounds. When the MA/ribose composition was administered orally and compared to MA, the serum concentration of Sb was significantly lower after 1 h and greater after 3 h. On the other hand, the MA/maltose composition showed similar serum Sb concentration after 1 h and higher level of Sb after 3 h, when compared to MA. In conclusion, the present study has demonstrated the formation of mixed or association complexes of MA with sugars, such as maltose and ribose, which promoted sustained serum level of Sb after oral administration.

Novel triphenylantimony(V) and triphenylbismuth(V) complexes with benzoic acid derivatives: structural characterization, in vitro antileishmanial and antibacterial activities and cytotoxicity against macrophages.

Two novel organoantimony(V) and two organobismuth(V) complexes of the type ML2 were synthesized, with L = acetylsalicylic acid (HL1) or 3-acetoxybenzoic acid (HL2) and M = triphenylantimony(V) (M1) or triphenylbismuth(V) (M2). Complexes, [M1(L1)2] (1), [M1(L2)2]∙CHCl3 (2), [M2(L1)2], (3) and [M2(L2)2] (4), were characterized by elemental analysis, IR and NMR. Crystal structures of triphenylantimony(V) dicarboxylate complexes 1 and 2 were determined by single crystal X-ray diffraction. Structural analyses revealed that 1 and 2 adopt five-coordinated extremely distorted trigonal bipyramidal geometries, binding with three phenyl groups in the equatorial position and two deprotonated organic ligands (L) in the axial sites. The metal complexes, their metal salts and ligands were evaluated in vitro for their activities against Leishmania infantum and amazonensis promastigotes and Staphylococcus aureus and Pseudomonas aeruginosa bacteria. Both the metal complexes showed antileishmanial and antibacterial activities but the bismuth complexes were the most active. Intriguingly, complexation of organobismuth(V) salt reduced its activity against Leishmania, but increased it against bacteria. In vitro cytotoxic test of these complexes against murine macrophages showed that antimony(V) complexes were the least toxic. Considering the selectivity indexes, organoantimony(V) complexes emerge as the most promising antileishmanial agents and organobismuth(V) complex 3 as the best antibacterial agent.

Proteome scale comparative modeling for conserved drug and vaccine targets identification in Corynebacterium pseudotuberculosis.

Corynebacterium pseudotuberculosis (Cp) is a pathogenic bacterium that causes caseous lymphadenitis (CLA), ulcerative lymphangitis, mastitis, and edematous to a broad spectrum of hosts, including ruminants, thereby threatening economic and dairy industries worldwide. Currently there is no effective drug or vaccine available against Cp. To identify new targets, we adopted a novel integrative strategy, which began with the prediction of the modelome (tridimensional protein structures for the proteome of an organism, generated through comparative modeling) for 15 previously sequenced C. pseudotuberculosis strains. This pan-modelomics approach identified a set of 331 conserved proteins having 95-100% intra-species sequence similarity. Next, we combined subtractive proteomics and modelomics to reveal a set of 10 Cp proteins, which may be essential for the bacteria. Of these, 4 proteins (tcsR, mtrA, nrdI, and ispH) were essential and non-host homologs (considering man, horse, cow and sheep as hosts) and satisfied all criteria of being putative targets. Additionally, we subjected these 4 proteins to virtual screening of a drug-like compound library. In all cases, molecules predicted to form favorable interactions and which showed high complementarity to the target were found among the top ranking compounds. The remaining 6 essential proteins (adk, gapA, glyA, fumC, gnd, and aspA) have homologs in the host proteomes. Their active site cavities were compared to the respective cavities in host proteins. We propose that some of these proteins can be selectively targeted using structure-based drug design approaches (SBDD). Our results facilitate the selection of C. pseudotuberculosis putative proteins for developing broad-spectrum novel drugs and vaccines. A few of the targets identified here have been validated in other microorganisms, suggesting that our modelome strategy is effective and can also be applicable to other pathogens.

Complete genome sequence of Corynebacterium pseudotuberculosis biovar ovis strain P54B96 isolated from antelope in South Africa obtained by rapid next generation sequencing technology.

The Actinobacteria, Corynebacterium pseudotuberculosis strain P54B96, a nonmotile, non-sporulating and a mesophile bacterium, was isolated from liver, lung and mediastinal lymph node lesions in an antelope from South Africa. This strain is interesting in the sense that it has been found together with non-tuberculous mycobacteria (NTMs) which could nevertheless play a role in the lesion formation. In this work, we describe a set of features of C. pseudotuberculosis P54B96, together with the details of the complete genome sequence and annotation. The genome comprises of 2.34 Mbp long, single circular genome with 2,084 protein-coding genes, 12 rRNA, 49 tRNA and 62 pseudogenes and a G+C content of 52.19%. The analysis of the genome sequence provides means to better understanding the molecular and genetic basis of virulence of this bacterium, enabling a detailed investigation of its pathogenesis.