An insight into the mechanism of inhibition of unusual bi-subunit topoisomerase I from Leishmania donovani by 3,3′-di-indolylmethane, a novel DNA topoisomerase I poison with a strong binding affinity to the enzyme

2007 ◽  
Vol 409 (2) ◽  
pp. 611-622 ◽  
Author(s):  
Amit Roy ◽  
Benu Brata Das ◽  
Agneyo Ganguly ◽  
Somdeb Bose Dasgupta ◽  
Neeta V. M. Khalkho ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Dna Cleavage ◽  
Topoisomerase I ◽  
Leishmania Donovani ◽  
Wide Spectrum ◽  
Free Enzyme ◽  
Rational Drug Design ◽  
Binary Complex

DIM (3,3′-di-indolylmethane), an abundant dietary component of cruciferous vegetables, exhibits a wide spectrum of pharmacological properties. In the present study, we show that DIM is a potent inhibitor of Leishmania donovani topoisomerase I with an IC50 of 1.2 μM. Equilibrium dialysis shows that DIM binds strongly to the free enzyme with a binding constant of 9.73×10−9 M. The binding affinity of DIM to the small subunit is 8.6-fold more than that of the large subunit of unusual LdTOP1LS (bi-subunit L. donovani topoisomerase I). DIM stabilizes topoisomerase I–DNA cleavage complexes in vitro and also in vivo. Like CPT (camptothecin), DIM inhibits the religation step when the drug was added to preformed topoisomerase I–DNA binary complex. Hence, DIM is similar to CPT with respect to its ability to form the topoisomerase I-mediated ‘cleavable complexes’ in vitro and in vivo. But unlike CPT, DIM interacts with both free enzyme and substrate DNA. Therefore DIM is a non-competitive class I inhibitor of topoisomerase I. DIM also inhibits the relaxation activity of the CPT-resistant mutant enzyme LdTOP1Δ39LS (N-terminal deletion of amino acids 1–39 of LdTOP1LS). The IC50 values of DIM in simultaneous and enzyme pre-incubation relaxation assays were 3.6 and 2.9 μM respectively, which are higher than that of wild-type topoisomerase I (LdTOP1LS), indicating that the affinity of DIM to LdTOP1Δ39LS is less than that for LdTOP1LS. This is the first report on DIM as an L. donovani topoisomerase I poison. Our study illuminates a new mode of action of enzyme inhibition by DIM that might be exploited for rational drug design in human leishmaniasis.

scholarly journals Susceptibility of leishmania to oxygen intermediates and killing by normal macrophages

1981 ◽  
Vol 153 (5) ◽  
pp. 1302-1315 ◽  
Author(s):  
HW Murray
Keyword(s):  
Glutathione Peroxidase ◽  
Leishmania Donovani ◽  
Wide Spectrum ◽  
Oxygen Intermediates ◽  
A Cell ◽  
Promastigote Form ◽  
Oxidative Products ◽  
Necessary And Sufficient

This study demonstrates that the promastigote form of virulent Leishmania donovani and Leishmania tropica are both deficient in endogenous enzymatic scavengers of H(2)0(2) (catalase, glutathione peroxidase) and susceptible to low fluxes of H(2)O(2) in a cell-free model. In addition, the killing of promastigotes by H(2)0(2) is markedly enhanced in the presence of a peroxidase and halide. Promastigotes also readily trigger the macrophage oxidative burst including the generation of H(2)0(2), and most intracellular promastigotes are killed within 18 h by unstimulated normal resident cells. Catalase, but not scavengers or quenchers of O(2)(-), OHx, or (1)O(2), protected promastigotes in a cell-free xanthine oxidase microbicidal system, and catalase also partially inhibited the leishmanicidal activity of resident macrophages. Thus, amongst various oxygen intermediates, H(2)0(2) alone appeared to be both necessary and sufficient for promastigote killing. Depriving macrophages of exogenous glucose, which inhibits the generation of oxygen intermediates, achieved effects similar to catalase treatment. These observations directly contrast with the intracellular parasite, T. gondii which is richly endowed with catalase and glutathione peroxidase, highly resistant to H(2)0(2), and requires products of O(2)(-)-H(2)0(2) interaction for effective oxidative killing. Toxoplasmas also fail to trigger the respiratory burst of normal macrophages, and readily multiply within these cells (1-5). Macrophages first activated by in vivo or in vitro immunologic stimuli, however, display an enhanced capacity to generate oxygen intermediates beyond O(2)(-) and H(2)0(2), and are able to kill toxoplasmas or inhibit their intracellular replication (1, 2). These studies illustrate the wide spectrum of susceptibility to oxidative products which appears to exist for virulent intracellular protozoans, and indicate that such differences may be reflected in contrasting fates of parasites within cell-free oxidative environments and the cytoplasm of normal resident macrophages. In addition, these observations also demonstrate that nonactivated phagocytes may display effective microbicidal activity against certain intracellular pathogens utilizing an oxygen-dependent mechanism.

scholarly journals High activity and low toxicity of a novel CD71-targeting nanotherapeutic named The-0504 on preclinical models of several human aggressive tumors

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Elisabetta Falvo ◽  
Verena Damiani ◽  
Giamaica Conti ◽  
Federico Boschi ◽  
Katia Messana ◽  
...  
Keyword(s):  
Topoisomerase I ◽  
Wide Spectrum ◽  
Drug Carrier ◽  
Disease Free Survival ◽  
Human Tumors ◽  
Repeat Dose ◽  
Multiple Cycle ◽  
Low Toxicity

Abstract Background Ferritin receptor (CD71) is an example of a very attractive cancer target, since it is highly expressed in virtually all tumor types, including metastatic loci. However, this target can be considered to be inaccessible to conventional target therapies, due to its presence in many healthy tissues. Here, we describe the preclinical evaluation of a tumor proteases-activatable human ferritin (HFt)-based drug carrier (The-0504) that is able to selectively deliver the wide-spectrum topoisomerase I inhibitor Genz-644282 to CD71-expressing tumors, preventing the limiting toxic effects associated with CD71-targeting therapies. Methods CD71 expression was evaluated using flow cytometry and immunohistochemistry techniques. The-0504 antiproliferative activity towards several cancer cell lines was assessed in vitro. The-0504 antitumor efficacy and survival benefit were evaluated in different human tumors, which had been grown either as xenografts or patient-derived xenografts in mice. The-0504 toxicology profile was investigated in multiple-cycle repeat-dose study in rodents. Results In vitro studies indicate that The-0504 is highly specific for CD71 expressing cells, and that there is a relationship between CD71 levels and The-0504 anticancer activity. In vivo treatments with The-0504 showed a remarkable efficacy, eradicating several human tumors of very diverse and aggressive histotypes, such as pancreas, liver and colorectal carcinomas, and triple-negative breast cancer. Conclusions Durable disease-free survival, persistent antitumor responses after discontinuation of treatment and favorable toxicology profile make The-0504 an ideal candidate for clinical development as a novel, CD71-targeted, low-toxicity alternative to chemotherapy.

Tamarix articulata (T. articulata) - An Important Halophytic Medicinal Plant with Potential Pharmacological Properties

2019 ◽  
Vol 20 (4) ◽  
pp. 285-292 ◽  
Author(s):  
Abdullah M. Alnuqaydan ◽  
Bilal Rah
Keyword(s):  
Medicinal Plant ◽  
Biological Activities ◽  
Wide Spectrum ◽  
Biological Properties ◽  
In Vivo Model ◽  
Drug Candidate ◽  
Phytochemical Analysis ◽  
Pharmacological Properties

Background:Tamarix Articulata (T. articulata), commonly known as Tamarisk or Athal in Arabic region, belongs to the Tamaricaece species. It is an important halophytic medicinal plant and a good source of polyphenolic phytochemical(s). In traditional medicines, T. articulata extract is commonly used, either singly or in combination with other plant extracts against different ailments since ancient times.Methods:Electronic database survey via Pubmed, Google Scholar, Researchgate, Scopus and Science Direct were used to review the scientific inputs until October 2018, by searching appropriate keywords. Literature related to pharmacological activities of T. articulata, Tamarix species, phytochemical analysis of T. articulata, biological activities of T. articulata extracts. All of these terms were used to search the scientific literature associated with T. articulata; the dosage of extract, route of administration, extract type, and in-vitro and in-vivo model.Results:Numerous reports revealed that T. articulata contains a wide spectrum of phytochemical(s), which enables it to have a wide window of biological properties. Owing to the presence of high content of phytochemical compounds like polyphenolics and flavonoids, T. articulata is a potential source of antioxidant, anti-inflammatory and antiproliferative properties. In view of these pharmacological properties, T. articulata could be a potential drug candidate to treat various clinical conditions including cancer in the near future.Conclusion:In this review, the spectrum of phytochemical(s) has been summarized for their pharmacological properties and the mechanisms of action, and the possible potential therapeutic applications of this plant against various diseases discussed.

Ferula hermonis: A Review of Current Use and Pharmacological Studies of its Sesquiterpene Ester Ferutinin

2020 ◽  
Vol 21 (5) ◽  
pp. 499-508 ◽  
Author(s):  
Rémi Safi ◽  
Marwan El-Sabban ◽  
Fadia Najjar
Keyword(s):  
Wide Spectrum ◽  
Endemic Plant ◽  
Anti Cancer ◽  
Pharmacological Studies ◽  
Sexual Impotence ◽  
Novel Applications ◽  
Anti Fungal ◽  
Sesquiterpene Ester

Ferula hermonis Boiss, is an endemic plant of Lebanon, locally known as “shilsh Elzallouh”. It has been extensively used in the traditional medicine as an aphrodisiac and for the treatment of sexual impotence. Crude extracts and isolated compounds of ferula hermonis contain phytoestrogenic substances having a wide spectrum of in vitro and in vivo pharmacological properties including anti-osteoporosis, anti-inflammatory, anti-microbial and anti-fungal, anti-cancer and as sexual activity enhancer. The aim of this mini-review is to highlight the traditional and novel applications of this plant’s extracts and its major sesquiterpene ester, ferutinin. The phytochemical constituents and the pharmacological uses of ferula hermonis crude extract and ferutinin specifically will be discussed.

Regulation of RNA helicase activity: principles and examples

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Pascal Donsbach ◽  
Dagmar Klostermeier
Keyword(s):  
Atp Hydrolysis ◽  
Wide Spectrum ◽  
Mrna Translation ◽  
Rna Degradation ◽  
Rna Helicases ◽  
Interaction Partners ◽  
Rna Duplexes ◽  
Self Association

Abstract RNA helicases are a ubiquitous class of enzymes involved in virtually all processes of RNA metabolism, from transcription, mRNA splicing and export, mRNA translation and RNA transport to RNA degradation. Although ATP-dependent unwinding of RNA duplexes is their hallmark reaction, not all helicases catalyze unwinding in vitro, and some in vivo functions do not depend on duplex unwinding. RNA helicases are divided into different families that share a common helicase core with a set of helicase signature motives. The core provides the active site for ATP hydrolysis, a binding site for the non-sequence-specific interactions with RNA, and in many cases a basal unwinding activity. Its activity is often regulated by flanking domains, by interaction partners, or by self-association. In this review, we summarize the regulatory mechanisms that modulate the activities of the helicase core. Case studies on selected helicases with functions in translation, splicing, and RNA sensing illustrate the various modes and layers of regulation in time and space that harness the helicase core for a wide spectrum of cellular tasks.

scholarly journals The DNA damage inducible lncRNA SCAT7 regulates genomic integrity and topoisomerase 1 turnover in lung adenocarcinoma

NAR Cancer ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Luisa Statello ◽  
Mohamad M Ali ◽  
Silke Reischl ◽  
Sagar Mahale ◽  
Subazini Thankaswamy Kosalai ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Cancer Biology ◽  
Topoisomerase I ◽  
Cell Cycle Checkpoints ◽  
Topoisomerase 1 ◽  
Damage Response ◽  
Promote Cell Survival

Abstract Despite the rapid improvements in unveiling the importance of lncRNAs in all aspects of cancer biology, there is still a void in mechanistic understanding of their role in the DNA damage response. Here we explored the potential role of the oncogenic lncRNA SCAT7 (ELF3-AS1) in the maintenance of genome integrity. We show that SCAT7 is upregulated in response to DNA-damaging drugs like cisplatin and camptothecin, where SCAT7 expression is required to promote cell survival. SCAT7 silencing leads to decreased proliferation of cisplatin-resistant cells in vitro and in vivo through interfering with cell cycle checkpoints and DNA repair molecular pathways. SCAT7 regulates ATR signaling, promoting homologous recombination. Importantly, SCAT7 also takes part in proteasome-mediated topoisomerase I (TOP1) degradation, and its depletion causes an accumulation of TOP1–cc structures responsible for the high levels of intrinsic DNA damage. Thus, our data demonstrate that SCAT7 is an important constituent of the DNA damage response pathway and serves as a potential therapeutic target for hard-to-treat drug resistant cancers.

scholarly journals Modulatory Effects of Osthole on Lipopolysaccharides-Induced Inflammation in Caco-2 Cell Monolayer and Co-Cultures with THP-1 and THP-1-Derived Macrophages

Nutrients ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 123
Author(s):  
Natalia K. Kordulewska ◽  
Justyna Topa ◽  
Małgorzata Tańska ◽  
Anna Cieślińska ◽  
Ewa Fiedorowicz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Inflammatory Reaction ◽  
Wide Spectrum ◽  
Cell Monolayer ◽  
In Vivo Studies ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Tnf Α

Lipopolysaccharydes (LPS) are responsible for the intestinal inflammatory reaction, as they may disrupt tight junctions and induce cytokines (CKs) secretion. Osthole has a wide spectrum of pharmacological effects, thus its anti-inflammatory potential in the LPS-treated Caco-2 cell line as well as in Caco-2/THP-1 and Caco-2/macrophages co-cultures was investigated. In brief, Caco-2 cells and co-cultures were incubated with LPS to induce an inflammatory reaction, after which osthole (150–450 ng/mL) was applied to reduce this effect. After 24 h, the level of secreted CKs and changes in gene expression were examined. LPS significantly increased the levels of IL-1β, -6, -8, and TNF-α, while osthole reduced this effect in a concentration-dependent manner, with the most significant decrease when a 450 ng/mL dose was applied (p < 0.0001). A similar trend was observed in changes in gene expression, with the significant osthole efficiency at a concentration of 450 ng/μL for IL1R1 and COX-2 (p < 0.01) and 300 ng/μL for NF-κB (p < 0.001). Osthole increased Caco-2 monolayer permeability, thus if it would ever be considered as a potential drug for minimizing intestinal inflammatory symptoms, its safety should be confirmed in extended in vitro and in vivo studies.

scholarly journals CHIR-124, a Novel Potent Inhibitor of Chk1, Potentiates the Cytotoxicity of Topoisomerase I Poisons In vitro and In vivo

2007 ◽  
Vol 13 (2) ◽  
pp. 591-602 ◽  
Author(s):  
Archie N. Tse ◽  
Katherine G. Rendahl ◽  
Tahir Sheikh ◽  
Haider Cheema ◽  
Kim Aardalen ◽  
...  
Keyword(s):  
Topoisomerase I ◽  
Potent Inhibitor

In vitro and in vivo leishmanicidal activity of Dysoxylum binectariferum and its fractions against Leishmania donovani

Phytomedicine ◽  
2007 ◽  
Vol 14 (1) ◽  
pp. 36-42 ◽  
Author(s):  
V. Lakshmi ◽  
K. Pandey ◽  
A. Kapil ◽  
N. Singh ◽  
M. Samant ◽  
...  
Keyword(s):  
Leishmania Donovani ◽  
Leishmanicidal Activity ◽  
Dysoxylum Binectariferum

scholarly journals In Vitro and In Vivo Activities of a Triterpenoid Saponin Extract (PX-6518) from the Plant Maesa balansae against Visceral Leishmania Species

2004 ◽  
Vol 48 (1) ◽  
pp. 130-136 ◽  
Author(s):  
Louis Maes ◽  
Dirk Vanden Berghe ◽  
Nils Germonprez ◽  
Ludo Quirijnen ◽  
Paul Cos ◽  
...  
Keyword(s):  
Leishmania Donovani ◽  
Human Fibroblasts ◽  
Subcutaneous Administration ◽  
Leishmania Species ◽  
Host Cells ◽  
Triterpenoid Saponin ◽  
Sodium Stibogluconate ◽  
Triterpenoid Saponins

ABSTRACT The in vitro and in vivo activities of a mixture of six oleane triterpene saponins, recovered from the methanolic extract of the leaves of the Vietnamese plant Maesa balansae (PX-6518), were evaluated against drug-sensitive visceral Leishmania strains. The in vitro 50% inhibitory concentration (IC50) against intracellular Leishmania infantum amastigotes was 0.04 μg/ml. The cytotoxic concentrations causing 50% cell death (CC50s) were about 1 μg/ml in murine macrophage host cells and >32 μg/ml in human fibroblasts (MRC-5 cell line). Evaluation in the Leishmania donovani BALB/c mouse model indicated that a single subcutaneous administration of 0.4 mg/kg at 1 day after infection reduced liver amastigote burdens by about 95% in all treated animals. If treatment was delayed until 14 days after infection, a dose of 1.6 mg/kg of body weight was required to maintain the same level of activity. Single 250-mg/kg doses of sodium stibogluconate (Pentostam) 1 and 14 days after infection produced comparable efficacies. A single dose of PX-6518 at 2.5 mg/kg administered 5 days before infection was still 100% effective in preventing liver infection, suggesting a particularly long residual action. Spleen and bone marrow could not be cleared by PX-6518 nor sodium stibogluconate. PX-6518 did not show activity after oral dosing at up to 200 mg/kg for 5 days. This study concludes that triterpenoid saponins from M. balansae show promising in vitro and in vivo antileishmanial potential and can be considered as new lead structures in the search for novel antileishmanial drugs.

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