Activation Of Caspase-like Proteases Research Articles

Caspase 3-like protease is involved in ethylene-induced programmed cell death during aerenchyma formation in Helianthus annuus stem.

Previous research has reported that hypoxic conditions and ethylene treatments greatly trigger programmed cell death (PCD) occurrence and induce the formation of aerenchyma to adapt stress environment in Helianthus annuus stem. Caspase 3-like protease (CLP) as regulatory signals, also be involved in the process of PCD to adapt the low oxygen environment. However, the relationships between ethylene and CLP have seldom been reported. Herein, To understand the regulatory role of ethylene and CLP signaling molecules in aerenchyma formation, we investigated the effects of exogenous ethephon (ET), ethylene perception inhibitor 1-methylcyclopropene (1-MCP), and the treatment of 1-MCP + ET on morphological, physiological characteristics and aerenchyma formation in H. annuus stem. The results showed that lysigenous aerenchyma formation in H. annuus stem is induced by ET, and immunohistochemistry assay indicate CLP activity is raised at the formation stage of aerenchyma formation, and decreased at the expanding phase of aerenchyma formation. Western blotting illustrate the expression of CLP is also increased within 8h after ethylene signaling inducing aerenchyma formation, and the activities of CLP are higher in ET treated seedlings than the control and 1-MCP treated seedlings. The same phenomenon was also observed by caspase-3 activity assay. These results revealed there is a causal and interdependent relationship between ET and CLP signaling during the process of aerenchyma formation, which regulating PCD initiation in H. annuus stem.

The role of melatonin on caspase-3-like activity and expression of the genes involved in programmed cell death (PCD) induced by in vitro salt stress in alfalfa (Medicago sativa L.) roots

BackgroundAlfalfa (Medicago sativa L.) is the most cultivated forage plant as a model in legumes. Salinity stress due to Na+ toxicity causes severe, oxidative stress as a main reason for program cell death (PCD) in plants. Melatonin application can increase plant productivity in response to diverse stressors via modulating plant antioxidant mechanisms and PCD inhibition in plants.ResultsAlfalfa roots were subjected to different concentrations of in vitro salinity supplemented with melatonin (0.1, 10 and 15 µM) for ten days. Application of melatonin under salinity stress reduced ROS, H2O2 and {text{O}}_{2}^{ - } content and showed a dramatic impact on TTC reduction and augmented cell viability. Interestingly, melatonin inhibited caspase 3-like protease activity and could decrease DNA fragmentation induced by salinity while increased expression of anti-apoptotic genes BI-1, UCP1-UCP2 involved in PCD pathway. In contrast, in 300 mM salinity, γVPE gene as a proapoptotic of PCD down-regulated significantly.ConclusionsFor the first time, present data showed that, melatonin plays a major function in preventing PCD in alfalfa root meristem cells. We attempted to offer a mechanism for the function of melatonin as an anti-apoptotic agent by demonstrating significant actions of melatonin on mitochondria proteins, such as UCPs, in a manner similar to animal cells.

Correction to: Reactive oxygen species, nitric oxide and plant cell death associated with caspase-like protease activity during somatic embryogenesis in Fraxinus mandshurica

Correction to: Reactive oxygen species, nitric oxide and plant cell death associated with caspase-like protease activity during somatic embryogenesis in Fraxinus mandshurica

Assessing PfGARP-Mediated Apoptosis of Blood-Stage Plasmodium falciparum Parasites.

Apoptosis is conventionally regarded as an evolutionarily conserved and genetically controlled process of programmed cell death confined to metazoan organisms. However, recently, conserved features of apoptosis have also been demonstrated in unicellular eukaryotes (Holzmuller et al. Parasitology 132:S19-S32, 2006; Le Chat et al. Mol Biochem Parasitol 153:41-47, 2007; Madeo et al. Curr Opin Microbiol 7:655-660, 2004; Welburn et al. Parasitology 132:S7-S18, 2006; Jensen et al. Science 216:1230-1233, 1982) including malaria parasites (Al-Olayan et al. Int J Parasitol 32:1133-1143, 2002; Ch'ng et al. Cell Death Dis 1:e26, 2010; Meslin et al. J Infect Dis 195:1852-1859, 2007; Picot et al. Trans R Soc Trop Med Hyg 91:590-591, 1997; Raj et al. Nature 582:104-108, 2020). P. falciparum glutamic-acid-rich protein (PfGARP) is an antigen of 80kDa that is uniquely expressed on the exofacial surface of red blood cells (RBCs) infected by early-to-late-trophozoite-stage P. falciparum parasites (Raj et al. Nature 582:104-108, 2020). We have recently demonstrated that antibodies against PfGARP bind to the PfGARP displayed on the surface of P. falciparum trophozoite-infected RBCs and trigger apoptosis in the intracellular parasites (Raj et al. Nature 582:104-108, 2020). This is the first demonstration of antibody-induced apoptosis in blood-stage malaria parasites and is characterized by several conserved features such as crisis form morphology, loss of mitochondrial membrane potential, loss of integrity of food vacuole, activation of caspase-like cysteine proteases, and fragmentation of chromosomal DNA. Here we describe the assays used to detect these features of apoptosis in the mature blood stage of malaria parasites.

Determination of Caspase-Like Activities in Roots by the Use of Fluorogenic Substrates.

Activity of proteases in tissues can be influenced by various intrinsic and extrinsic factors. One of the activities that is regularly monitored in organisms ranging from prokaryotes to metazoans is the -aspase-like activity: activity of proteases, which cleave their substrates after the negatively charged amino acid residues, especially the aspartic acid. This activity is also known as the caspase-like activity, since the caspases, metazoan cysteine proteases, are one of the best characterized proteases with Asp-directed activities. Plants do not contain caspases; however, various plant proteases have been shown to exhibit caspase-like activity including saspases, phytaspases, and legumains (VPEs). The activity of these proteases can change in plants in response to stress. Here we present a simple method for monitoring of the caspase-like protease activity in roots, which have been treated with allelopathic extracts, using a set of commercially available caspase substrates. We show that activity towards some, but not all, caspase substrates is upregulated in treated but not control samples. The protocol can be used also for other plant tissues as well as for other stressors.

Reactive oxygen species, nitric oxide and plant cell death associated with caspase-like protease activity during somatic embryogenesis in Fraxinus mandshurica

Programmed cell death occurs in browning explants of Fraxinus mandshurica during somatic embryogenesis, but the underlying mechanism is unclear. In this study, single cotyledons of zygotic embryos of F. mandshurica were used as explants. Mitochondrial structure and function, caspase-3-like protease activity, hydrogen peroxide metabolism, and nitric oxide accumulation induced by high concentrations of sucrose and plant growth regulators were studied. The results show that plant growth regulators induced somatic embryogenesis and also promoted explant browning. High sucrose concentrations had similar effects. High concentrations of sucrose and plant growth regulators led to the accumulation of hydrogen peroxide and nitric oxide which induced changes in mitochondrial structure and function such as modifications in mitochondrial morphology, increased membrane permeability, decreased membrane potential, and the release of cytochrome c into the cytoplasm. An increase in caspase-3-like protease activity triggered programmed cell death in some browning explant cells. During somatic embryogenesis there were increased activities of superoxide dismutase, peroxidase, and catalase, which are associated with hydrogen peroxide metabolism and jointly maintain reactive oxygen species levels. Intracellular nitric oxide synthase and nitrate reductase activities were not significantly correlated with nitric oxide content. Instead, intracellular nitric oxide may be derived from non-enzymatic reactions. Our results indicate that hydrogen peroxide and nitric oxide may function as signals, playing key roles in somatic embryogenesis and programmed cell death of explant cells of F. mandshurica. The interaction between nitric oxide and reactive oxygen species determines the occurrence of programmed cell death in explant cells; somatic embryogenesis and programmed cell death are positively regulated by hydrogen peroxide. However, the regulation of nitric oxide is complex.

Selenium restores mitochondrial dysfunction to reduce Cr-induced cell apoptosis in Chinese cabbage (Brassica campestris L. ssp. Pekinensis) root tips

Chromium (Cr) disrupts the growth and physiology of plants. Selenium (Se) is considered as a promising option to help plants ameliorate Cr toxicity. To investigate the effects of exogenous Se on reactive oxygen species (ROS) burst and programmed cell death (PCD) in root tip cells under Cr stress, hydroponic experiments were carried out with Chinese cabbage seedlings grown in Hoagland solution containing 1 mg L-1 Cr and 0.1 mg L-1 Se. Results showed that Se scavenged the overproduction of H2O2 and O2－·, and alleviated the level of lipid peroxidation in root tips stressed by Cr. Moreover, Se effectively prevented DNA degradation and reduced the number of apoptotic cells in root tips. Compared with Cr treatment, Se supplementation reduced the content of ROS and malondialdehyde in mitochondria by 38.23% and 17.52%, respectively. Se application decreased the opening degree of mitochondrial permeability transition pores by 32.30%, increased mitochondrial membrane potential by 40.91%, alleviated the release of cyt c from mitochondria into cytosol by 18.42% and caused 57.40% decrease of caspase 3-like protease activity, and thus restored mitochondrial dysfunction caused by Cr stress. In addition, the alteration of Se on mitochondrial physiological properties maintained calcium homeostasis between mitochondria and cytosol, which further contributed to reducing the appearance of Cr-induced PCD. Findings suggested that Se restored mitochondrial dysfunction, which further rescued root tip cells from PCD, consequently activating defense strategies to protect plants from Cr toxicity and maintaining plant growth.

Short-term waterlogging-induced autophagy in root cells of wheat can inhibit programmed cell death.

Autophagy is a pathway for the degradation of cytoplasmic components in eukaryotes. In wheat, the mechanism by which autophagy regulates programmed cell death (PCD) is unknown. Here, we demonstrated that short-term waterlogging-induced autophagy inhibited PCD in root cells of wheat. The waterlogging-tolerant wheat cultivar Huamai 8 and the waterlogging-sensitive wheat cultivar Huamai 9 were used as experimental materials, and their roots were waterlogged for 0-48h. Waterlogging stress increased the number of autophagic structures, the expression levels of autophagy-related genes (TaATG), and the occurrence of PCD in root cells. PCD manifested as morphological changes in the cell nucleus, significant enhancement of DNA laddering bands, and increases in caspase-like protease activity and the expression levels of metacaspase genes. The autophagy promoter rapamycin (RAPA) reduced PCD levels, whereas the autophagy inhibitor 3-methyladenine (3-MA) enhanced them. The expression levels of TaATG genes and the number of autophagic structures were lower in cortex cells than in stele cells, but the levels of PCD were higher in cortex cells. The number of autophagic structures was greater in Huamai 8 than in Huamai 9, but the levels of PCD were lower. In summary, our results showed that short-term waterlogging induced autophagy which could inhibit PCD. Mechanisms of response to waterlogging stress differed between cortex and stele cells and between two wheat cultivars of contrasting waterlogging tolerance.

Caspase-like proteases and the phytohormone cytokinin as determinants of S-RNAse-based self-incompatibility-induced PCD in Petunia hybrida L.

S-RNAse-based self-incompatibility (SI) in petunia (Petunia hybrida L.) is a self-/non-self-recognition system underlying the pistil rejection of self-pollen. Using different methods, including a TUNEL assay, we have recently shown that programmed cell death (PCD) is a factor of the SI in petunia. Here, we show that the growth of self-incompatible pollen tubes in the style tissues during 4h after pollination is accompanied by five-sixfold increase in a caspase-like protease (CLP) activity. Exogenous cytokinin (CK) inhibits the pollen tube growth and stimulates the CLP activity in compatible pollen tubes. The actin depolymerization with latrunculin B induces a sharp drop in the CLP activity in self-incompatible pollen tubes and its increase in compatible pollen tubes. Altogether, our results suggest that a CLP is involved in the SI-induced PCD and that CK is a putative activator of the CLP. We assume that CK provokes acidification of the cytosol and thus promotes the activation of a CLP. Thus, our results suggest that CK and CLP are involved in the S-RNAse-based SI-induced PCD in petunia. Potential relations between these components in PCD signaling are discussed.

The Bactrocera dorsalis caspase-1 gene is expressed throughout development and required for female fertility.

The oriental fruit fly Bactrocera dorsalis is one of the most destructive pests of fruits and vegetables. The sterile insect technique (SIT) is an effective and environmentally friendly approach to the control of tephritid fruit flies. The pro-apoptotic gene head involution defective (hid) has been used as an effective lethal effector in SIT. It initiates an interaction cascade including activation of caspase-like proteases. However, the biological role of caspase activity in tephritid fruit flies has yet to be explored. In this study, the B. dorsalis caspase-1 gene (Bdcp-1) was cloned and characterized. Sequence comparison showed that Bdcp-1 protein shared highly homology with Drosophila effector caspases Drice and Dcp-1. It is predicted to contain a short pro-domain because two proteolytic cleavage sites (Asp16 and Asp223 ) are present. Expression patterns indicated that Bdcp-1 is highly transcribed in embryos and expression was upregulated during metamorphosis and upon ultraviolet irradiation. RNA interference showed that Bdcp-1 is essential for ovarian development and female fertility. For example, knockdown of Bdcp-1 caused transcriptional downregulation of expression of the yolk protein-1 gene (Bdyp-1) and delayed ovarian development. The percentage of spawning females and female fecundity were significantly reduced. This study illustrates the function of the Bdcp-1 gene and provides an attractive method to develop a biological way to control the oriental fruit fly through the control of caspases. © 2020 Society of Chemical Industry.

Inhibition of jasmonate-mediated plant defences by the fungal metabolite higginsianin B.

Infection of Arabidopsis thaliana by the ascomycete fungus Colletotrichum higginsianum is characterized by an early symptomless biotrophic phase followed by a destructive necrotrophic phase. The fungal genome contains 77 secondary metabolism-related biosynthetic gene clusters, whose expression during the infection process is tightly regulated. Deleting CclA, a chromatin regulator involved in the repression of some biosynthetic gene clusters through H3K4 trimethylation, allowed overproduction of three families of terpenoids and isolation of 12 different molecules. These natural products were tested in combination with methyl jasmonate, an elicitor of jasmonate responses, for their capacity to alter defence gene induction in Arabidopsis. Higginsianin B inhibited methyl jasmonate-triggered expression of the defence reporter VSP1p:GUS, suggesting it may block bioactive jasmonoyl isoleucine (JA-Ile) synthesis or signalling in planta. Using the JA-Ile sensor Jas9-VENUS, we found that higginsianin B, but not three other structurally related molecules, suppressed JA-Ile signalling by preventing the degradation of JAZ proteins, the repressors of jasmonate responses. Higginsianin B likely blocks the 26S proteasome-dependent degradation of JAZ proteins because it inhibited chymotrypsin- and caspase-like protease activities. The inhibition of target degradation by higginsianin B also extended to auxin signalling, as higginsianin B treatment reduced auxin-dependent expression of DR5p:GUS. Overall, our data indicate that specific fungal secondary metabolites can act similarly to protein effectors to subvert plant immune and developmental responses.

Rosmarinic acid inhibits programmed cell death in Solanum tuberosum L. calli under high salinity

Oxidative stress induced by salinity is a prime cause of cell death when Na+ toxicity becomes unbearable. We explored the effect of rosmarinic acid (RA) on the Solanum tuberosum L. cv. Desiree calli against salt-induced programmed cell death (PCD). We showed that PCD events were triggered in calli under 250 mM NaCl by the loss of plasma membrane integrity as measured by the amount of malondialdehyde (MDA) in the cytoplasm, the degree of DNA degradation resulting from the cleavage of nuclear DNA into oligonucleosomal fragments in apoptotic cells, the presence of TUNEL-positive nuclei (90 ± 0.005%) damage in genomic DNA, and activation of caspase 3-like protease. Callus Formation Medium (CFM) supplemented with RA led to the suppression of salt-induced cell death and a dramatic decrease in the MDA level and frequency of TUNEL-positive nuclei under salinity to 4 ± and 7.3 ± % in the presence of 50 and 350 μM RA, respectively. The application of RA also resulted in an increase in GSH content and maintenance of a high GSH/GSSG ratio. Interestingly, these reductions in PCD were accompanied by inhibiting caspase 3-like protease activities due to RA under salinity. Molecular docking predicted high binding energies of RA for binding to subtilisin-like protease (StSCTc-3), which has caspase-3 like activity in Solanum tuberosum, near the active site. This finding supports the notion of a role for RA in PCD protection in plants, which is consistent with earlier reports in animal cells.

Hsp70 plays a role in programmed cell death during the remodelling of leaves of the lace plant (Aponogeton madagascariensis).

Lace plant leaves utilize programmed cell death (PCD) to form perforations during development. The role of heat shock proteins (Hsps) in PCD during lace plant leaf development is currently unknown. Hsp70 amounts were measured throughout lace plant leaf development, and the results indicate that it is highest before and during PCD. Increased Hsp70 amounts correlate with raised anthocyanin content and caspase-like protease (CLP) activity. To investigate the effects of Hsp70 on leaf development, whole plants were treated with either of the known regulators of PCD [reactive oxygen species (ROS) or antioxidants] or an Hsp70 inhibitor, chlorophenylethynylsulfonamide (PES-Cl). ROS treatment significantly increased Hsp70 2-fold and CLP activity in early developing leaves, but no change in anthocyanin and the number of perforations formed was observed. Antioxidant treatment significantly decreased Hsp70, anthocyanin, and CLP activity in early leaves, resulting in the fewest perforations. PES-Cl (25 μM) treatment significantly increased Hsp70 4-fold in early leaves, while anthocyanin, superoxide, and CLP activity significantly declined, leading to fewer perforations. Results show that significantly increased (4-fold) or decreased Hsp70 amounts lead to lower anthocyanin and CLP activity, inhibiting PCD induction. Our data support the hypothesis that Hsp70 plays a role in regulating PCD at a threshold in lace plant leaf development. Hsp70 affects anthocyanin content and caspase-like protease activity, and helps regulate PCD during the remodelling of leaves of lace plant, Aponogeton madagascariensis.

The effects of different pharmacological agent treatments on ROS accumulation and functional protein activities in wheat endosperm PCD

Wheat (Triticum aestivum L.) is one of the top three food crops in the world. Studies have revealed that wheat endosperm development undergoes programmed cell death (PCD) process development that may be influenced by PCD. Waterlogging and exogenous hydrogen peroxide (H2O2) treatment exacerbates wheat endosperm PCD, whereas PCD acceleration is significantly inhibited by reactive oxygen species (ROS) scavengers. To explore the physiological mechanism of waterlogging resistance in wheat, the effects of exogenous H2O2, ascorbic acid (AsA), and cyclosporin A (CsA) treatment on ROS content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity in the endosperm of Huamai 8 (waterlogging-tolerant wheat cultivar) and Huamai 9 (waterlogging-sensitive wheat cultivar) were studied. The results showed that exogenous H2O2 treatment resulted in an increase in ROS content, antioxidant enzyme activity, mitochondrial membrane permeability, release of cytochrome c, and caspase-like protease activity in the endosperms of both wheat cultivars, which eventually exacerbated PCD. Compared to Huamai 8, the increase in ROS content in Huamai 9 was more significant, whereas changes in antioxidant enzyme activity, cytochrome c release, mitochondrial membrane permeability, and caspase-like protease activity were smaller. Exogenous AsA treatment leads to the content of H2O2 and catalase activity decrease, which could inhibit endosperm cell death to some extent. CsA treatment effectively inhibited the increase in H2O2 content, antioxidant enzyme activity, release of cytochrome c, and caspase-like protease activity caused by exogenous H2O2 treatment, which in turn inhibited cell death. In summary, exogenous H2O2 treatment aggravates endosperm PCD, and Huamai 9 exhibited higher ROS accumulation and a weaker antioxidant enzyme system under external stress, which may be the mechanisms underlying its sensitivity to waterlogging. CsA effectively inhibited the increase in ROS, antioxidant enzyme activity, cytochrome c release, and cell death. It is possible that in wheat endosperm, mitochondria in a similar way to animal mitochondria release cytochrome c regulating PCD.

Glabridin triggers over-expression of apoptosis inducing factor (AIF) gene in Candida albicans.

Background and Purpose: Candida albicans is a prevalent human fungal pathogen that can cause a wide spectrum of diseases, from superficial mucosal infections to systemic disorders, in patients with impaired immunity. Glabridin is a pyranoisoflavan originally extracted from root extract of Glycyrrhiza glabra. Glabridin can also mediate apoptosis in yeast cells by changing the mitochondrial membrane potential, activation of caspase-like proteases, and DNA cleavage. The aim of this study was to investigate the mechanism of action of glabridin in C. albicans.Materials and Methods: Candida albicans ATCC14053 was applied as the standard strain. Total RNA was extracted from the isolate under glabridin-treated and untreated conditions. To evaluate the alternations in the apoptosis inducing factor (AIF) gene expression, real-time polymerase chain reaction (real-time -PCR) was performed, and the obtained data were analyzed using REST software.Results: Expression of the AIF gene was represented as the ratio of expression relative to the reference gene. According to the REST® output, the expression of the AIF gene increased significantly (P<0.05) under the glabridin-treated condition.Conclusion:Our results suggested that glabridin may induce apoptosis through the caspase-independent route and might be considered as an anti-Candida agent.

Quercetin suppresses the chymotrypsin-like activity of proteasome via inhibition of MEK1/ERK1/2 signaling pathway in hepatocellular carcinoma HepG2 cells.

The proteasomal system is a promising target for cancer treatment. Quercetin (Que), a flavonoid compound with antitumor ability, displays the inhibitory effect on proteasome activity. However, the underlying molecular mechanisms are ill defined. The present study found that Que treatment significantly reduced the chymotrypsin-like protease activity of proteasome whereas the trypsin- and caspase-like protease activities remained unchanged in HepG2 cancer cells, along with activation of p38 MAPK and JNK and reduction of ERK1/2 phosphorylation. Que-reduced proteasome activity could not be reverted by inhibition of p38 MAPK and JNK signaling pathway. In addition, MEK1 overexpression or knockdown upregulated or downregulated the chymotrypsin-like protease activity of proteasome, respectively. Both Que and MEK1/ERK1/2 inhibitor attenuated the expression levels of proteasome β subunits. These results indicate that Que-induced suppression of MEK1/ERK1/2 signaling and subsequent reduction of proteasome β subunits is responsible for its inhibitory impacts on proteasome activity.

Nitric oxide suppresses aluminum-induced programmed cell death in peanut (Arachis hypoganea L.) root tips by improving mitochondrial physiological properties

Aluminum (Al) stress alters nitric oxide (NO) and induces programmed cell death (PCD) in plants. Recent study has shown that NO inhibits Al-induced PCD. However, the mechanism of NO inhibiting Al-induced PCD has not been revealed yet. Here, we investigated the behavior of mitochondria during Al-induced PCD suppressed by NO in peanut. Seedlings of peanut was grown hydroponically in a controllable growth room. The mitochondrial physiological parameters were determined spectrophotometrically. The expression of AhANT and AhHsp70 was determined by quantitative RT-PCR. Al-induced cell death rapidly in peanut root tips is mitochondria-dependent PCD. There was a significantly negative relationship between PCD and mitochondrial NO/H2O2 level. Compared with Al treatment alone, the addition of NO donor sodium nitroprusside (SNP) increased the ratio of NO/H2O2, down-regulated AhANT expression and inhibited the opening of mitochondrial permeability transition pore (MPTP), up-regulated AhHsp70 expression and increased mitochondrial inner membrane potential (ΔΨm), reduced cytochrome c (Cyt c) release from mitochondria and caspase 3-like protease activity, while the effect of NO specific scavenger cPTIO supplement was opposite. NO suppresses Al-induce PCD in peanut root tips by improving mitochondrial physiological properties.

Analysis of Mitochondrial Markers of Programmed Cell Death.

Mitochondria play a crucial role in programmed cell death (PCD) in plants. In most cases of mitochondria-dependent PCD, cytochrome c (Cyt c) released from mitochondria due to the opening of mitochondrial permeability transition pore (MPTP) and the activation of caspase-like proteases. Here we describe the analytic methods of mitochondrial markers of PCD including mitochondria isolation, mitochondrial membrane permeability, mitochondrial inner membrane potential, Cytc release, ATP, and mitochondrial reactive oxygen species (ROS).

Treatment of 2nd stage posterior tibial tendon deficiency (PTTD)

In vitro and in vivo anti-leishmanial efficacy of copper salisylaldoxime (CuSAL), a transition metal complex, was evaluated and the underlying mechanism was studied. In vitro studies revealed that 30 μM of CuSAL causes 96% reduction in parasite burden in infected macrophages. CuSAL is least toxic in host cells. A dose of 5 mg/kg bodyweight per mice on alternate days (5 doses) gives ∼97% protection in both liver and spleen. Moreover, CuSAL potentially inhibits the catalytic activity of LdTOPILS and causes apoptosis of Leishmania parasites through induction of intracellular ROS generation and activation of caspase-like proteases. Interestingly, CuSAL does not inhibit the catalytic activity of human topoisomerase I. The present study illuminated that CuSAL, has potent anti-leishmanial activity, which selectively targets LdTOPILS; and is a safe for human. Therefore, this compound might be highly promising candidate to develop the rational approaches for chemotherapy of human leishmaniasis.

Copper salisylaldoxime (CuSAL) imparts protective efficacy against visceral leishmaniasis by targeting Leishmania donovani topoisomerase IB

In vitro and in vivo anti-leishmanial efficacy of copper salisylaldoxime (CuSAL), a transition metal complex, was evaluated and the underlying mechanism was studied. In vitro studies revealed that 30 μM of CuSAL causes 96% reduction in parasite burden in infected macrophages. CuSAL is least toxic in host cells. A dose of 5 mg/kg bodyweight per mice on alternate days (5 doses) gives ∼97% protection in both liver and spleen. Moreover, CuSAL potentially inhibits the catalytic activity of LdTOPILS and causes apoptosis of Leishmania parasites through induction of intracellular ROS generation and activation of caspase-like proteases. Interestingly, CuSAL does not inhibit the catalytic activity of human topoisomerase I. The present study illuminated that CuSAL, has potent anti-leishmanial activity, which selectively targets LdTOPILS; and is a safe for human. Therefore, this compound might be highly promising candidate to develop the rational approaches for chemotherapy of human leishmaniasis.