Camptothecin induced mitochondrial dysfunction leading to programmed cell death in unicellular hemoflagellate Leishmania donovani

Development of Amphotericin B Decorated Gold Nanoparticles as a Promising Antileishmanial Nanoconjugate

Leishmaniasis, attributed to the protozoan parasite Leishmania, manifests in diverse clinical forms, including cutaneous, mucocutaneous, and visceral leishmaniasis; VL constitutes a significant global health menace. Prevalent in tropical and subtropical regions, this affliction disproportionately impacts individuals below the poverty threshold, transmitted through the bite of female sandflies. Existing treatments, such as pentavalent antimony, miltefosine, and Amphotericin B, exhibit limitations. Despite the emergence of liposomal Amphotericin B (AmBisome) as a promising antileishmanial agent, its utility is impeded by adverse effects, elevated production expenses, and cytotoxicity. To address these challenges, our investigation introduces a potential remedy─a citrate-coated gold Amphotericin B nanoparticle formulation. Characterized using dynamic light scattering and transmission electron microscopy, this pioneering formulation exhibited efficacy against L. donovani Ag83 promastigotes as demonstrated by MTT cell viability testing. Evaluating internal reactive oxygen species (ROS) levels and dual staining with acridine orange and ethidium bromide unveiled its consequential impact on cell death. Significantly, our study discloses this novel nanoformulation's unprecedented inhibition of the trypanothione reductase enzyme. The findings posit the citrate-coated gold Amphotericin B nanoformulation as a promising and targeted antileishmanial agent, representing potential advancements in leishmaniasis therapeutics.

Enzyme-instructed intramitochondrial polymerization for enhanced anticancer treatment without the development of drug-resistance

Intracellular polymerization in living cells motivated chemists to generate polymeric structures with a multitude of possibilities to interact with biomacromolecules. However, out-of-control of the intracellular chemical reactions would be an obstacle restricting its application, providing the toxicity of non-targeted cells. Here, we reported intracellular thioesterase-mediated polymerization for selectively occurring polymerization using disulfide bonds in cancer cells. The acetylated monomers did not form disulfide bonds even under an oxidative environment, but they could polymerize into the polymeric structure after cleavage of acetyl groups only when encountered activity of thioesterase enzyme. Furthermore, acetylated monomers could be self-assembled with doxorubicin, providing doxorubicin loaded micelles for efficient intracellular delivery of drug and monomers. Since thioesterase enzymes were overexpressed in cancer cells specifically, the micelles were disrupted under activity of the enzyme and the polymerization could occur selectively in the cancer mitochondria. The resulting polymeric structures disrupted the mitochondrial membrane, thus activating the cellular death of cancer cells with high selectivity. This strategy selectively targets diverse cancer cells involving drug-resistant cells over normal cells. Moreover, the mitochondria targeting strategy overcomes the development of drug resistance even with repeated treatment. This approach provides a way for selective intracellular polymerization with desirable anticancer treatment.

Cell Death in Leishmania donovani promastigotes in response to Mammalian Aurora Kinase B Inhibitor- Hesperadin

Deciphering how hesperadin, a repurposed mammalian aurora kinase B inhibitor, affects the cellular pathways in Leishmania donovani might be beneficial. This investigation sought to assess the physiological effects of hesperadin on promastigotes of L. donovani, by altering the duration of treatment following exposure to hesperadin. Groups pre-treated with inhibitors such as EGTA, NAC, and z-VAD-fmk before hesperadin exposure were also included. Morphological changes by microscopy, ATP and ROS changes by luminometry; DNA degradation using agarose gel electrophoresis and metacaspase levels through RT-PCR were assessed. Flow cytometry was used to study mitochondrial depolarization using JC-1 and MitoTracker Red; mitochondrial-superoxide accumulation using MitoSOX; plasma membrane modifications using Annexin-V and propidium iodide, and lastly, caspase activation using ApoStat. Significant alterations in promastigote morphology were noted. Caspase activity and mitochondrial-superoxide rose early after exposure whereas mitochondrial membrane potential demonstrated uncharacteristic variations, with significant functional disturbances such as leakage of superoxide radicals after prolonged treatments. ATP depletion and ROS accumulation demonstrated inverse patterns, genomic DNA showed fragmentation and plasma membrane showed Annexin-V binding, soon followed by propidium iodide uptake. Multilobed macronuclei and micronuclei accumulated in hesperadin exposed cells before they disintegrated into necrotic debris. The pathologic alterations were unlike the intrinsic or extrinsic pathways of classical apoptosis and suggest a caspase-mediated cell death most akin to mitotic-catastrophe. Most likely, a G2/M transition block caused accumulation of death signals, disorganized spindles and mechanical stresses, causing changes in morphology, organellar functions and ultimately promastigote death. Thus, death was a consequence of mitotic-arrest followed by ablation of kinetoplast functions, often implicated in L. donovani killing.

A Cascade-Amplified Pyroptosis Inducer: Optimizing Oxidative Stress Microenvironment by Self-Supplying Reactive Nitrogen Species Enables Potent Cancer Immunotherapy

Selective generation of sufficient pyroptosis inducers at the tumor site without external stimulation holds immense significance for a longer duration of immunotherapy. Here, we report a cascade-amplified pyroptosis inducer CSCCPT/SNAP that utilizes reactive nitrogen species (RNS), self-supplied from the diffusion-controlled reaction between reactive oxygen species (ROS) and nitric oxide (NO) to potentiate pyroptosis and immunotherapy, while both endogenous mitochondrial ROS stimulated by released camptothecin and released NO initiate pyroptosis. Mechanistically, cascade amplification of the antitumor immune response is prompted by the cooperation of ROS and NO and enhanced by RNS with a long lifetime, which could be used as a pyroptosis trigger to effectively compensate for the inherent drawbacks of ROS, resulting in long-lasting pyroptosis for favoring immunotherapy. Tumor growth is efficiently inhibited in mouse melanoma tumors through the facilitation of reactive oxygen/nitrogen species (RONS)-NO synergy. In summary, our therapeutic approach utilizes supramolecular engineering and nanotechnology to integrate ROS producers and NO donors of tumor-specific stimulus responses into a system that guarantees synchronous generation of these two reactive species to elicit pyroptosis-evoked immune response, while using self-supplied RNS as a pyroptosis amplifier. RONS-NO synergy achieves enhanced and sustained pyroptosis and antitumor immune responses for robust cancer immunotherapy.

ROS-responsive and triple-synergistic mitochondria-targeted polymer micelles for efficient induction of ICD in tumor therapeutics

Immunogenic cell death (ICD) represents a modality of apoptosis distinguished by the emanation of an array of damage-related molecular signals. This mechanism introduces a novel concept in the field of contemporary tumor immunotherapy. The inception of reactive oxygen species (ROS) within tumor cells stands as the essential prerequisite and foundation for ICD induction. The formulation of highly efficacious photodynamic therapy (PDT) nanomedicines for the successful induction of ICD is an area of significant scientific inquiry. In this work, we devised a ROS-responsive and triple-synergistic mitochondria-targeted polymer micelle (CAT/CPT-TPP/PEG-Ce6, CTC) that operates with multistage amplification of ROS to achieve the potent induction of ICD. Utilizing an "all-in-one" strategy, we direct both the PDT and chemotherapeutic units to the mitochondria. Concurrently, a multistage cyclical amplification that caused by triple synergy strategy stimulates continuous, stable, and adequate ROS generation (domino effect) within the mitochondria of cells. Conclusively, influenced by ROS, tumor cell-induced ICD is effectively activated, remodeling immunogenicity, and enhancing the therapeutic impact of PDT when synergized with chemotherapy. Empirical evidence from in vitro study substantiates that CTC micelles can efficiently provoke ICD, catalyzing CRT translocation, the liberation of HMGB1 and ATP. Furthermore, animal trials corroborate that polymer micelles, following tail vein injection, can induce ICD, accumulate effectively within tumor tissues, and markedly inhibit tumor growth subsequent to laser irradiation. Finally, transcriptome analysis was carried out to evaluate the changes in tumor genome induced by CTC micelles. This work demonstrates a novel strategy to improve combination immunotherapy using nanotechnology.

Combining photodynamic therapy and cascade chemotherapy for enhanced tumor cytotoxicity: the role of CTT2P@B nanoparticles

The mitochondria act as the main producers of reactive oxygen species (ROS) within cells. Elevated levels of ROS can activate the mitochondrial apoptotic pathway, leading to cell apoptosis. In this study, we devised a molecular prodrug named CTT2P, demonstrating notable efficacy in facilitating mitochondrial apoptosis. To develop nanomedicine, we enveloped CTT2P within bovine serum albumin (BSA), resulting in the formulation known as CTT2P@B. The molecular prodrug CTT2P is achieved by covalently conjugating mitochondrial targeting triphenylphosphine (PPh3), photosensitizer TPPOH2, ROS-sensitive thioketal (TK), and chemotherapeutic drug camptothecin (CPT). The prodrug, which is chemically bonded, prevents the escape of drugs while they circulate throughout the body, guaranteeing the coordinated dispersion of both medications inside the organism. Additionally, the concurrent integration of targeted photodynamic therapy and cascade chemotherapy synergistically enhances the therapeutic efficacy of pharmaceutical agents. Experimental results indicated that the covalently attached prodrug significantly mitigated CPT cytotoxicity under dark conditions. In contrast, TPPOH2, CTT2, CTT2P, and CTT2P@B nanoparticles exhibited increasing tumor cell-killing effects and suppressed tumor growth when exposed to light at 660 nm with an intensity of 280 mW cm-2. Consequently, this laser-triggered, mitochondria-targeted, combined photodynamic therapy and chemotherapy nano drug delivery system, adept at efficiently promoting mitochondrial apoptosis, presents a promising and innovative approach to cancer treatment.

DNA topoisomerases as a drug target in Leishmaniasis: Structural and mechanistic insights

Leishmaniasis, caused by a protozoan parasite, is among humanity's costliest banes, owing to the high mortality and morbidity ratio in poverty-stricken areas. To date, no vaccine is available for the complete cure of the disease. Current chemotherapy is expensive, has undesirable side effects, and faces drug resistance limitations and toxicity concerns. The substantial differences in homology between leishmanial DNA topoisomerase IB compared with the human counterparts provided a new lead in the study of the structural determinants that can be targeted. Several research groups explored this molecular target, trying to fill the therapeutic gap, and came forward with various anti-leishmanial scaffolds. This article is a comprehensive review of knowledge about topoisomerases as an anti-leishmanial drug target and their inhibitors collected over the years. In addition to information on molecular targets and reported scaffolds, the review details the structure-activity relationship of described compounds with leishmanial Topoisomerase IB. Moreover, the work also includes information about the structure of the inhibitors, showing common interacting residues with leishmanial topoisomerases that drive their mode of action towards them. Finally, in search of topoisomerase inhibitors at the stage of clinical trials, we have listed all the drugs that have been in clinical trials against leishmaniasis.

Intracellular FGF1 protects cells from apoptosis through direct interaction with p53

Fibroblast growth factor 1 (FGF1) acts by activating specific tyrosine kinase receptors on the cell surface. In addition to this classical mode of action, FGF1 also exhibits intracellular activity. Recently, we found that FGF1 translocated into the cell interior exhibits anti-apoptotic activity independent of receptor activation and downstream signaling. Here, we show that expression of FGF1 increases the survival of cells treated with various apoptosis inducers, but only when wild-type p53 is present. The p53-negative cells were not protected by either ectopically expressed or translocated FGF1. We also confirmed the requirement of p53 for the anti-apoptotic intracellular activity of FGF1 by silencing p53, resulting in loss of the protective effect of FGF1. In contrast, in p53-negative cells, intracellular FGF1 regained its anti-apoptotic properties after transfection with wild-type p53. We also found that FGF1 directly interacts with p53 in cells and that the binding region is located in the DBD domain of p53. We therefore postulate that intracellular FGF1 protects cells from apoptosis by directly interacting with p53.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

Tumor permeable self-delivery nanodrug targeting mitochondria for enhanced chemotherapy

Drug self-delivery systems (DSDSs) have been extensively exploited to enhance drug loading capacity and avoid excipient-related toxicity issues. However, deficient tumor targeting, inferior tumor permeability, prominent burst release, and nonspecific subcellular distribution remain major obstacles. Herein, we reported a ROS-responsive amphiphilic prodrug (CPT-S-NO) synthesized by the conjugation of zwitterionic tertiary amine-oxide (TAO) moiety and hydrophobic camptothecin (CPT) through a thioether linkage, which formed a nanoparticulate DSDS in an aqueous solution. CPT-S-NO, compared with CPT-11 and the water-soluble TAO-modified CPT prodrug (CPT-NO), exhibited prolonged blood circulation, enhanced tumor accumulation, deep tumor penetration, efficient mitochondrial targeting, and ROS-activated drug release to induce mitochondrial dysfunction, corporately conducing to the superior antitumor efficacy in vivo. This TAO decoration strategy promises potential applications in designing multipotent DSDSs for various drugs.

Anti-Leishmania amazonensis Activity, Cytotoxic Features, and Chemical Profile of Allium sativum (Garlic) Essential Oil

Human tegumentary leishmaniasis (HTL) is a serious tropical disease caused by Leishmania amazonensis. Developing new leishmanicidal agents can help overcome current treatment challenges, such as drug resistance and toxicity. Essential oils are a source of lipophilic substances with diverse therapeutic properties. This study aimed to determine the anti-L. amazonensis activity, cytotoxicity, and chemical profile of Allium sativum essential oil (ASEO). The effect of ASEO on parasite and mammalian cells viability was evaluated using resazurin and MTT assays, respectively. The oil's effect against intracellular amastigotes was also determined. Transmission electron microscopy was used to assess the ultrastructural changes induced by ASEO. In addition, the chemical constituents of ASEO were identified by gas chromatography-mass spectrometry (GC-MS). The cytotoxic potential was evaluated in vitro and in silico. The oil displayed IC₅₀ of 1.76, 3.46, and 3.77 µg/mL against promastigotes, axenic, and intracellular amastigotes, respectively. Photomicrographs of treated parasites showed plasma membrane disruption, increased lipid bodies, and autophagic-like structures. ASEO chemical profiling revealed 1,2,4,6-tetrathiepane (24.84%) and diallyl disulfide (16.75%) as major components. Computational pharmacokinetics and toxicological analysis of ASEO's major components demonstrated good oral bioavailability and better toxicological endpoints than the reference drugs. Altogether, the results suggest that ASEO could be an alternative drug candidate against HTL.

Discovery, SAR and mechanistic studies of quinazolinone-based acetamide derivatives in experimental visceral leishmaniasis

Towards identification of novel therapeutic candidates, a series of quinazolinone-based acetamide derivatives were synthesized and assessed for their anti-leishmanial efficacy. Amongst synthesized derivatives, compounds F12, F27 and F30 demonstrated remarkable activity towards intracellular L. donovani amastigotes in vitro, with IC₅₀ values of 5.76 ± 0.84 μM, 3.39 ± 0.85 μM and 8.26 ± 1.23 μM against promastigotes, and 6.02 μM ± 0.52, 3.55 ± 0.22 μM and 6.23 ± 0.13 μM against amastigotes, respectively. Oral administration of compounds F12 and F27 entailed >85% reduction in organ parasite burden in L. donovani-infected BALB/c mice and hamsters, by promoting host-protective Th1 cytokine response. In host J774 macrophages, mechanistic studies revealed inhibition of PI3K/Akt/CREB axis, resulting in a decrease of IL-10 versus IL-12 release upon F27 treatment. In silico docking studies conducted with lead compound, F27 demonstrated plausible inhibition of Leishmania prolyl-tRNA synthetase, which was validated via detection of decreased proline levels in parasites and induction of amino acid starvation, leading to G₁ cell cycle arrest and autophagy-mediated programmed cell death of L. donovani promastigotes. Structure-activity analysis and study of pharmacokinetic and physicochemical parameters suggest oral availability and underscore F27 as a promising lead for anti-leishmanial drug development.

Antiparasitic Activity of Two Natural Terpenes from Salvia cuspidata against Leishmania amazonensis

Leishmaniasis is a neglected disease caused by flagellated parasites of the Leishmania genus affecting more than 10 million people worldwide. Current treatments for leishmaniasis involve the administration of poorly tolerated drugs with toxic side effects in patients. There is an imperative necessity for novel compounds to treat this disease. One of the most used strategies in the search for different antiparasitic compounds is the screening of purified plant molecules. The diterpenes 12-hydroxy-11,14-diketo-6,8,12-abietatrien-19,20-olide (HABTO) and 5-epi-icetexone (ICTX) isolated from Salvia cuspidata were shown to be effective against Leishmania amazonensis in vitro and in vivo. They displayed an antiproliferative effect against L. amazonensis promastigotes. They also induce an increase in ROS levels and affect the mitochondrial activity of parasites. HABTO and ICTX in an in vivo model of cutaneous leishmaniasis decrease footpad swelling, parasite load, and splenic index. Moreover, they induce significant reduction in the O.D. of total anti-Leishmania IgG and IgG1 subtype antibody responses against L. amazonensis compared to the PBS group but maintain high levels of IgG2a. This suggests that in HABTO- or ICTX-treated mice, there is a slowdown in the progression of the disease. These terpenes could be considered as possible novel antileishmanial agents against L. amazonensis and thus treat cutaneous leishmaniasis.

Novel Pyrido[2',1':2,3]imidazo[4,5-c]quinoline Derivative Selectively Poisons Leishmania donovani Bisubunit Topoisomerase 1 to Inhibit the Antimony-Resistant Leishmania Infection in Vivo

The unique bisubunit structure of Leishmania donovani topoisomerase 1B (LdTop1) is a potential drug target in the parasites unlike the monomeric Top1 from its human host counterpart. Here, we report the design, synthesis, and validation of a chimeric pyrido[2',1':2,3]imidazo[4,5-c]quinoline derivative (C17) as a novel antileishmanial agent that poisons topoisomerase 1-DNA covalent complexes (LdTop1cc) inside the parasites and inhibits Top1 religation activity both in the drug sensitive and antimony-resistant L. donovani clinical isolates. Importantly, the human Top1 is not sensitive to C17. Further, C17 overcomes the chemical instability of camptothecin (CPT) by generating persistent LdTop1cc-induced DNA breaks inside the parasites even after 12 h of drug removal. Intraperitoneal administration of C17 results in marked reduction of the Leishmania amastigotes from the infected spleen and liver of BALB/c mice. C17 confers a host protective immune-response up-regulating the Th1 cytokines facilitating parasite clearance which can be exploited for treating drug-resistant leishmaniasis.

Stimuli-responsive drug delivery systems triggered by intracellular or subcellular microenvironments

Drug delivery systems (DDS) triggered by local microenvironment represents the state-of-art of nanomedicine design, where the triggering hallmarks at intracellular and subcellular levels could be employed to exquisitely recognize the diseased sites, reduce side effects, and expand the therapeutic window by precisely tailoring the drug-release kinetics. Though with impressive progress, the DDS design functioning at microcosmic levels is fully challenging and underexploited. Here, we provide an overview describing the recent advances on stimuli-responsive DDSs triggered by intracellular or subcellular microenvironments. Instead of focusing on the targeting strategies as listed in previous reviews, we herein mainly highlight the concept, design, preparation and applications of stimuli-responsive systems in intracellular models. Hopefully, this review could give useful hints in developing nanoplatforms proceeding at a cellular level.

Demystifying the potential of inhibitors targeting DNA topoisomerases in unicellular protozoan parasites

DNA topoisomerases are a group of enzymes omnipresent in all organisms. They maintain the DNA topology during replication, repair, recombination, and transcription. However, the structure of topoisomerase in protozoan parasites differs significantly from that of human topoisomerases; thus, this enzyme acts as a crucial target in drug development against parasitic diseases. Although the therapeutic potential of drugs targeting the parasitic topoisomerase is well known, to manage the shortcomings of currently available therapeutics and the emergence of drug resistance, the discovery of novel antiparasitic molecules is an urgent need. In this review, we describe various investigational and repurposed topoisomerase inhibitors developed against protozoan parasites over the past few years. Teaser: Fatal parasitic diseases are an increasing cause for concern; here, we provide a compilation of different inhibitors targeting DNA topoisomerases, enzymes that are essential for, and unique to, protozoan parasites; therefore, inhibitors are efficient and have few adverse effects.

Holanamine, a Steroidal Alkaloid from the Bark of Holarrhena pubescens Wall. ex G. Don Inhibits the Growth of Leishmania donovani by Targeting DNA Topoisomerase 1B

Leishmaniasis is a group of neglected tropical diseases (NTDs) caused by about 20 species of obligate intracellular protozoan parasites of the genus Leishmania, which occurs in cutaneous, mucocutaneous, and visceral forms. Many researchers have sought to utilize natural products for novel and effective treatments to combat many infectious diseases, including leishmaniasis. Holarrhena pubescens Wall. ex G. Don (Apocynaceae) bark is a rich source of bioactive steroidal alkaloids. The total alkaloidal extract (IC₅₀ 6.12 ± 0.117 μg/mL), and the isolated alkaloid, holanamine, showed significant antileishmanial activity (IC₅₀ 2.66 ± 0.112 μM against AG83 and 3.80 ± 0.126 μM against BHU-575) against the Leishmania donovani parasite, better than miltefosine (IC₅₀ 19.61 ± 0.093 μM against AG83 and 23.20 ± 0.094 μM against BHU-575). Holanamine inhibited the L. donovani topoisomerase 1B (LdToP1B) in a non-competitive manner (IC₅₀ 2.81 ± 0.105 μM), indicating that it interacts with the free enzyme and enzyme-DNA complex without inhibiting human topoisomerase. Hydrogen bonding and hydrophobic interactions of holanamine with the N-terminal and hinge region of the large subunit of LTop1B is responsible for its potent antileishmanial activity, as shown by docking studies. Treatment with holanamine causes apoptotic-like cell death by generating cellular and mitochondrial reactive oxygen species, disrupting the mitochondrial membrane potential and inducing ultrastructural alterations in the promastigotes. Holanamine effectively clears intracellular amastigotes but minimally affects host macrophages with no significant cytotoxicity in HEK 293 and L929 cell lines. Thus, our studies show that holanamine can further be used to develop effective antileishmanial agents against evolving drug-resistant parasites.

Mitochondria-Driven Dye Rearrangement That Enables Spatiotemporally Controlled Photomedicine

Reversibly controlling the dye arrangements in living systems has great potential to realize spatiotemporally controlled photomedicine. However, tuning or even maintaining a certain arrangement of dyes in a complex living environments is extremely challenging due to the interference of the various biological species. Herein, a conceptual supramolecular strategy to engineer a switchable photosensitizer (PS) via mitochondria-mediated dynamic interconversion between monomer and J-aggregation, enabling specific activation of the mitochondria-targeting photodynamic therapy (PDT) and hibernation after mitochondria damage is presented. The presented mitochondria-mediated "activate-then-hibernate" PS design enables a fascinating spatiotemporally controlled PDT in which spatially controlled mitochondrial-targeting enhances therapeutic efficacy and temporally controlled activation-then-hibernation averts off-target damage during PDT and tissue damage after clinical treatment, thus offering significant potential for biological research and clinical needs.

Amino acid containing amphiphilic hydrogelators with antibacterial and antiparasitic activities

Nanoscale self-assembly of peptide constructs represents a promising means to present bioactive motifs to develop new functional materials. Here, we present a series of peptide amphiphiles which form hydrogels based on β-sheet nanofibril networks, several of which have very promising anti-microbial and anti-parasitic activities, in particular against multiple strains of Leishmania including drug-resistant ones. Aromatic amino acid based amphiphilic supramolecular gelators C₁₄-Phe-CONH-(CH₂)_n-NH₂ (n = 6 for P1 and n = 2 for P3) and C₁₄-Trp-CONH-(CH₂)_n-NH₂ (n = 6 for P2 and n = 2 for P4) have been synthesized and characterized, and their self-assembly and gelation behaviour have been investigated in the presence of ultrapure water (P1, P2, and P4) or 2% DMSO(v/v) in ultrapure water (P3). The rheological, morphological and structural properties of the gels have been comprehensively examined. The amphiphilic gelators (P1 and P3) were found to be active against both Gram-positive bacteria B. subtilis and Gram-negative bacteria E. coli and P. aeruginosa. Interestingly, amphiphiles P1 and P3 containing an L-phenylalanine residue show both antibacterial and antiparasitic activities. Herein, we report that synthetic amphiphiles with an amino acid residue exhibit a potent anti-protozoan activity and are cytotoxic towards a wide array of protozoal parasites, which includes Indian varieties of Leishmania donovani and also kill resistant parasitic strains including BHU-575, MIL^R and CPT^R cells. These gelators are highly cytotoxic to promastigotes of Leishmania and trigger apoptotic-like events inside the parasite. The mechanism of killing the parasite is shown and these gelators are non-cytotoxic to host macrophage cells indicating the potential use of these gels as therapeutic agents against multiple forms of leishmaniasis in the near future.

Cyclodextrin-based supramolecular nanoparticles break the redox balance in chemodynamic therapy-enhanced chemotherapy

Drug delivery based on abnormal features of the tumor microenvironment (TME) has attracted considerable interest worldwide. In this study, we proposed an applicable strategy to increase the reactive oxygen species (ROS) and inhibit glutathione (GSH), in an effort to amplify oxidative damage in prostate cancer cells. Specifically, we developed dual-responsive supramolecular self-assembled nanoparticles (NPs) based on polymerized methacrylic acid (MA) and polymerized poly(ethylene glycol) dimethyl acrylate-modified β-cyclodextrin (CD) with ferrocene (Fc)-connected (S) (+)-camptothecin (CPT) (designated as MA-CD/Fc-CPT NPs). The as-prepared negatively charged supramolecular NPs can be taken up by tumor cells successfully owing to their reversible negative-to-positive charge transition capacity at acidic pH. The supramolecular NPs increased ROS generation and decreased GSH to amplify oxidative stress and improve the therapeutic effect of chemotherapy. As expected, MA-CD/Fc-CPT NPs displayed good drug delivery capabilities to tumor cells or tissues. MA-CD/Fc-CPT NPs also inhibited cancer cell proliferation in both the cells and tissues. This result was partially due to increased ROS generation and decreased GSH, which contributed to more pronounced oxidative stress. The as-prepared supramolecular NPs displayed great biosafety to normal tissues. According to our results, negatively charged supramolecular MA-CD/Fc-CPT NPs are well-suited for drug delivery and improved cancer treatment in TMEs.

Iron(III) Coordinated Theranostic Polyprodrug with Sequential Receptor-Mitochondria Dual Targeting and T1-Weighted Magnetic Resonance Imaging Potency for Effective and Precise Chemotherapy

The sequential cancer cell receptor and mitochondria dual-targeting single delivery agent deliver chemotherapeutic drug effectively and precisely at the targeted site has become a promising strategy to enhance the drug efficacy and suppressions of cancer cell drug resistance prominence. Herein, required specialty molecules like a chemotherapeutic drug [camptothecin (CPT)], mitochondriotropic segment (triphenyl phosphonium cation) receptor targeting ligand (biotin), and magnetic resonance imaging (MRI)-contrast agent (iron-complex) were tethered to the polyprodrug, CP TP PG BN Fe, using the ring-opening metathesis polymerization technique for potential chemotherapy and simultaneous MRI-based diagnosis. This amphiphilic polyprodrug spontaneously aggregated into nanospheres and exhibited remarkable T₁-weighted MRI proficiency. Detail in vitro cellular studies revealed unambiguous mitochondrial delivery of CPT, which eventually enhanced the chemotherapeutic efficacy of CP TP PG BN Fe. Therefore, MRI-tracking, receptor-mitochondria dual targeting, theranostic polyprodrug, and CP TP PG BN Fe opened the way for effective and precise chemotherapy, which would have the attractive potential for diagnosis and decisive dose determination in clinical implications.

An update on dual targeting strategy for cancer treatment

The key issue in the treatment of solid tumors is the lack of efficient strategies for the targeted delivery and accumulation of therapeutic cargoes in the tumor microenvironment (TME). Targeting approaches are designed for more efficient delivery of therapeutic agents to cancer cells while minimizing drug toxicity to normal cells and off-targeting effects, while maximizing the eradication of cancer cells. The highly complicated interrelationship between the physicochemical properties of nanoparticles, and the physiological and pathological barriers that are required to cross, dictates the need for the success of targeting strategies. Dual targeting is an approach that uses both purely biological strategies and physicochemical responsive smart delivery strategies to increase the accumulation of nanoparticles within the TME and improve targeting efficiency towards cancer cells. In both approaches, either one single ligand is used for targeting a single receptor on different cells, or two different ligands for targeting two different receptors on the same or different cells. Smart delivery strategies are able to respond to triggers that are typical of specific disease sites, such as pH, certain specific enzymes, or redox conditions. These strategies are expected to lead to more precise targeting and better accumulation of nano-therapeutics. This review describes the classification and principles of dual targeting approaches and critically reviews the efficiency of dual targeting strategies, and the rationale behind the choice of ligands. We focus on new approaches for smart drug delivery in which synthetic and/or biological moieties are attached to nanoparticles by TME-specific responsive linkers and advanced camouflaged nanoparticles.

The Natural Alkaloid Tryptanthrin Induces Apoptosis-like Death in Leishmania spp

Leishmaniasis is a vector-borne disease against which there are no approved vaccines, and the treatment is based on highly toxic drugs. The alkaloids consist of a chemical class of natural nitrogen-containing substances with a long history of antileishmanial activity. The present study aimed at determining the antileishmanial activity and in silico pharmacokinetic and toxicological potentials of tryptanthrin alkaloid. The anti-Leishmania amazonensis and anti-L. infantum assays were performed against both promastigotes and intracellular amastigotes. Cellular viability was determined by parasites’ ability to grow (promastigotes) or differentiate (amastigotes) after incubation with tryptanthrin. The mechanisms of action were explored by mitochondrion dysfunction and apoptosis-like death evaluation. For the computational pharmacokinetics and toxicological analysis (ADMET), tryptanthrin was submitted to the PreADMET webserver. The alkaloid displayed anti-promastigote activity against L. amazonensis and L. infantum (IC₅₀ = 11 and 8.0 μM, respectively). Tryptanthrin was active against intracellular amastigotes with IC₅₀ values of 75 and 115 μM, respectively. Mitochondrial membrane depolarization was observed in tryptanthrin-treated promastigotes. In addition, parasites undergoing apoptosis-like death were detected after 18 h of exposure. In silico ADMET predictions revealed that tryptanthrin has pharmacokinetic and toxicological properties similar to miltefosine. The results presented herein demonstrate that tryptanthrin is an interesting drug candidate against leishmaniasis.

Thymoquinone Induced Leishmanicidal Effect via Programmed Cell Death in Leishmania donovani

Visceral leishmaniasis (VL) or kala-azar is a vector-borne dreaded protozoal infection that is caused by the parasite Leishmania donovani. With increases in the dramatic infection rates, present drug toxicity, resistance, and the absence of an approved vaccine, the development of new antileishmanial compounds from plant sources remains the keystone for the control of visceral leishmaniasis. In this study, we evaluated the leishmanicidal effect of thymoquinone against L. donovani with an in vitro and ex vivo model. Thymoquinone exhibited potent antipromastigote activity with IC₅₀ and IC₉₀ concentrations achieved at 6.33 ± 1.21 and 20.71 ± 2.15 μM, respectively, whereas the IC₅₀ and IC₉₀ concentrations were found to be 7.83 ± 1.65 and 27.25 ± 2.20 μM against the intramacrophagic form of amastigotes, respectively. Morphological changes in promastigotes and growth reversibility study following treatment confirmed the leishmanicidal effect of thymoquinone. Further, thymoquinone exhibited leishmanicidal activities against L. donovani promastigote through cytoplasmic shrinkage, membrane blebbing, chromatin condensation, cellular and nuclear shrinkage, and DNA fragmentation, as observed under scanning and transmission electron microscopy analyses. The antileishmanial activity was exerted via programmed cell death as proved by exposure of phosphatidylserine, DNA nicking by TUNEL assay, and loss of mitochondrial membrane potential. Thymoquinone at a concentration of 200 μM was devoid of any cytotoxic effects against mammalian macrophage cells. Thymoquinone showed strong leishmanicidal activity against L. donovani, which is mediated via an apoptosis mode of parasitic cell death, and accordingly, thymoquinone may be the source of a new lead molecule for the cure of VL.

TDP1 knockout Leishmania donovani accumulate topoisomerase 1-linked DNA damage and are hypersensitive to clinically used antileishmanial drugs

Leishmania donovani, a unicellular protozoan parasite, causes a wide range of human diseases including fatal visceral leishmaniasis. Tyrosyl DNA-phosphodiesterase 1 (TDP1) hydrolyzes the phosphodiester bond between DNA 3'-end and a tyrosyl moiety of trapped topoisomerase I-DNA covalent complexes (Top1cc). We have previously shown Leishmania harbors a TDP1 gene (LdTDP1), however, the biological role of TDP1 remains largely unknown. In the present study, we have generated TDP1 knockout L. donovani (LdTDP1^-/- ) promastigotes and have shown that LdTDP1^-/- parasites are deficient in 3'-phosphodiesterase activities and were hypersensitive to Top1-poison like camptothecin (CPT), DNA alkylation agent like methyl methanesulfonate, and oxidative DNA lesions generated by hydrogen peroxide but were not sensitive to etoposide. We also detected elevated levels of CPT-induced reactive oxygen species triggering cell cycle arrest and cell death in LdTDP1^-/- promastigotes. LdTDP1^-/- promastigotes accumulate a significant change in the membrane morphology with the accumulation of membrane pores, which is associated with oxidative stress and lipid peroxidation. To our surprise, we detected that LdTDP1^-/- parasites were hypersensitive to antileishmanial drugs like amphotericin B and miltefosine, which could be rescued by complementation of wild-type TDP1 gene in the LdTDP1^-/- parasites. Notably, multidrug-resistant L. donovani clinical isolates showed a marked reduction in TDP1 expression and were sensitive to Top1 poisons. Taken together, our study provides a new role of LdTDP1 in protecting L. donovani parasites from oxidative stress-induced DNA damage and resistance to amphotericin B and miltefosine.

Mitochondria-Targeting Chemodynamic Therapy Nanodrugs for Cancer Treatment

Mitochondria, as one of the most critical subcellular organelles of cancer cells, are very vulnerable and often on the verge of oxidative stress. The classic chemodynamic therapy (CDT) directly employs endogenous chemical energy to trigger reactive oxygen species (ROS) burst and destroy tumor cells. However, the effectiveness of CDT is restricted by the limited diffusion distance and short half-life of ROS. From this perspective, the treatment method (mitochondria-targeting chemodynamic therapy nanodrugs, M-CDT nanodrugs) that can generate high levels of ROS at the mitochondrial site is extremely efficient and promising for cancer treatment. Currently, many emerging M-CDT nanodrugs have been demonstrated excellent spatial specificity and anti-cancer efficacy. In this minireview, we review various proof-of-concept researches based on different M-CDT nanodrugs designs to overcome the limits of the efficacy of CDT, mainly divided into four strategies: supplying H2O2, non-H2O2 dependent CDT, eliminating GSH and enhancing by hyperthermia therapy (HT). These well-designed M-CDT nanodrugs greatly increase the efficacy of CDT. Finally, the progress and potential of M-CDT nanodrugs are discussed, as well as their limitations and opportunities.

Potential Anti-leishmanial Activity of a Semi-purified Fraction Isolated from the Leaves of Parthenium hysterophorus

PURPOSE

In the present perspective, emergence of resistant strains of Leishmania donovani and severe side effects resulting from the use of conventional anti-leishmanial therapies present an urgent need for developing novel agents against this parasite. We have explored the effectiveness of secondary plant metabolites as alternative choices in the treatment for visceral leishmaniasis (vl).

METHODS

The plant Parthenium hysterophorus L. (Asteraceae) was collected from the West Bengal State University Campus, Barasat, West Bengal, India. The leaves of this plant were extracted by different solvents, such as ethyl acetate, water, petroleum ether and hexane. Gas chromatography-mass spectrometry (GC-MS) analysis was also carried out for the identification of compounds in the hexane soluble fraction (PHFd) with substantial anti-leishmanial activities. The antipromastigote activity and cytotoxicity of this fraction were evaluated by the tetrazolium MTT assay. Other biochemical and physiological parameters were studied by microscopic observation and flow cytometric analyses.

RESULTS

PHFd showed considerable activity against L. donovani promastigotes (IC₅₀: 20 µg/ml). The PHFd also inhibited in vitro growth of L. major LV39 promastigotes dose dependently with an IC₅₀ of 40 µg/ml. The GC-MS studies of this particular fraction revealed the presence of four major compounds with different retention times (RT) of 26.08, 33.11, 36.41, and 41.20 min. In this study, we also established that PHFd could induce DNA damage and subsequent apoptosis of L. donovani promastigotes with a concomitant increase in generations of reactive oxygen species (ROS) in a time-dependent manner. This fraction was also found to be effective in nitric oxide-mediated inhibition of intracellular amastigotes (IC₅₀:12.5 µg/ml) without any noticeable cytotoxicity towards murine splenocytes in vitro.

CONCLUSION

This study provides the basis for additional phytochemical and pharmacological studies on the antiprotozoal applications of P. hysterophorus.

Chalcones identify cTXNPx as a potential antileishmanial drug target

With current drug treatments failing due to toxicity, low efficacy and resistance; leishmaniasis is a major global health challenge that desperately needs new validated drug targets. Inspired by activity of the natural chalcone 2’,6’-dihydroxy-4’-methoxychalcone (DMC), the nitro-analogue, 3-nitro-2’,4’,6’- trimethoxychalcone (NAT22, 1c) was identified as potent broad spectrum antileishmanial drug lead. Structural modification provided an alkyne containing chemical probe that labelled a protein within the parasite that was confirmed as cytosolic tryparedoxin peroxidase (cTXNPx). Crucially, labelling is observed in both promastigote and intramacrophage amastigote life forms, with no evidence of host macrophage toxicity. Incubation of the chalcone in the parasite leads to ROS accumulation and parasite death. Deletion of cTXNPx, by CRISPR-Cas9, dramatically impacts upon the parasite phenotype and reduces the antileishmanial activity of the chalcone analogue. Molecular docking studies with a homology model of in-silico cTXNPx suggest that the chalcone is able to bind in the putative active site hindering access to the crucial cysteine residue. Collectively, this work identifies cTXNPx as an important target for antileishmanial chalcones.

Leishmaniasis is an insect vector-borne parasitic disease. With >350 million people world wide considered at risk, 12 million people currently infected and an economic cost that can be estimated in terms of >3.3 million working life years lost, leishmaniasis is a major global health challenge. The disease is of particular importance in Brazil. Current treatment of leishmaniasis is difficult requiring a long, costly course of drug treatment using old drugs with poor safety indications requiring close medical supervision. Moreover, resistance to current antileishmanials is growing, emphasising a major need for new drug targets. In earlier work we had identified a naturally inspired chalcone which had promising antileishmanial activity but with no known mode of action. In this work we use an analogue of this molecule as an activity based probe to identify a protein target of the chalcone. This protein, cTXNPx, has a major role in protecting the parasite against attack by reactive oxygen species in the host cell. By inhibiting this protein the parasite can no longer survive in the host. Collectively this work validates cTXNPx as a drug target with the chalcone as a lead structure for future drug discovery programmes.

Sesamol Induces Apoptosis-Like Cell Death in Leishmania donovani

Background

Visceral leishmaniasis (VL), caused by the protozoan parasite Leishmania donovani (L. donovani), is the most severe form of leishmaniasis. It is largely responsible for significant morbidity and mortality in tropical and subtropical countries. Currently, available therapeutics have lots of limitations including high-cost, adverse side-effects, painful route of administration, less efficacy, and resistance. Therefore, it is time to search for cheap and effective antileishmanial agents. In the present work, we evaluated the antileishmanial potential of sesamol against promastigotes as well as intracellular amastigotes. Further, we tried to work out its mechanism of antileishmanial action on parasites through different assays.

Methodology

In vitro and ex vivo antileishmanial assays were performed to evaluate the antileishmanial potential of sesamol on L. donovani. Cytotoxicity was determined by MTT assay on human THP-1-derived macrophages. Sesamol-induced morphological and ultrastructural changes were determined by electron microscopy. H₂DCFDA staining, JC-1dye staining, and MitoSOX red staining were performed for reactive oxygen assay (ROS), mitochondrial membrane potential, and mitochondrial superoxide, respectively. Annexin V/PI staining for apoptosis, TUNEL assay, and DNA laddering for studying sesamol-induced DNA fragmentation were performed.

Conclusions

Sesamol inhibited the growth and proliferation of L. donovani promastigotes in a dose-dependent manner. It also reduced the intracellular parasite load without causing significant toxicity on host-macrophages. Overall, it showed antileishmanial effects through induction of ROS, mitochondrial dysfunction, DNA fragmentation, cell cycle arrest, and apoptosis-like cell death to parasites. Our results suggested the possible use of sesamol for the treatment of leishmaniasis after further in vivo validations.

A polymer‑calcium phosphate nanocapsule for RNAi-induced oxidative stress and cascaded chemotherapy

As most of intracellular reactive oxygen species (ROS) is produced in the mitochondria, mitochondrial modulation of cancer cell is a promising strategy for maximizing the in situ-activable combination therapy of oxidative catastrophe and cascaded chemotherapy. Herein, a serum-stable polymer‑calcium phosphate (CaP) hybrid nanocapsule carrying siRNA against ADP-ribosylation factor 6 (Arf6) overexpressed in cancer cells and parent drug camptothecin (CPT), designated as PTkCPT/siRNA, was developed for the RNAi-induced oxidative catastrophe and cascaded chemotherapy. A copolymer of mPEG-P(Asp-co-TkCPT), covalently tethered with chemotherapeutic CPT via a ROS-labile dithioketal (Tk) linker, was synthesized and self-assembled into a PTkCPT micelle as a nanotemplate for the CaP mineralization. The as-prepared PTkCPT/siRNA nanoparticle showed a core-shell-distinct nanocapsule which was consisted of a spherical polymeric core enclosed within a CaP shell capable of releasing siRNA in response to lysosomal acidity. Blocking Arf6 signal pathway of cancer cells led to their mitochondrial aggregation and subsequently induced a burst of ROS for oxidative catastrophe, which further triggered the cascaded CPT chemotherapy via the breakage of ROS-labile dithioketal linker. This strategy of RNAi-induced oxidative catastrophe and cascaded chemotherapy resulted in a significant combination effect on cancer cell killing and tumor growth inhibition in mice with low side effects, and provided a promising paradigm for precise cancer therapy.

A camptothecin prodrug induces mitochondria-mediated apoptosis in cancer cells with cascade activations

Mitochondria are crucial regulators of the intrinsic pathway of apoptosis. Herein, we report a photosensitizer-conjugated camptothecin (CPT)-based prodrug for combinative chemo-photodynamic treatment of solid tumors with cascade activations. Upon light irradiation, our prodrug can effectively target the mitochondria of cancer cells, generate singlet oxygen to increase the level of reactive oxygen species (ROS) and trigger ROS-responsive release of CPT, which synergistically induce mitochondrial damage and cause the apoptosis of cancer cells, therefore achieving high therapeutic efficacy for solid tumors and minimized adverse effects to normal tissues. Our prodrug holds great promise as a potent and inspiring means for cancer treatment.

Mito-Bomb: Targeting Mitochondria for Cancer Therapy

Cancer has been one of the most common life-threatening diseases for a long time. Traditional cancer therapies such as surgery, chemotherapy (CT), and radiotherapy (RT) have limited effects due to drug resistance, unsatisfactory treatment efficiency, and side effects. In recent years, photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) have been utilized for cancer treatment owing to their high selectivity, minor resistance, and minimal toxicity. Accumulating evidence has demonstrated that selective delivery of drugs to specific subcellular organelles can significantly enhance the efficiency of cancer therapy. Mitochondria-targeting therapeutic strategies are promising for cancer therapy, which is attributed to the essential role of mitochondria in the regulation of cancer cell apoptosis, metabolism, and more vulnerable to hyperthermia and oxidative damage. Herein, the rational design, functionalization, and applications of diverse mitochondria-targeting units, involving organic phosphine/sulfur salts, quaternary ammonium (QA) salts, peptides, transition-metal complexes, guanidinium or bisguanidinium, as well as mitochondria-targeting cancer therapies including PDT, PTT, CDT, and others are summarized. This review aims to furnish researchers with deep insights and hints in the design and applications of novel mitochondria-targeting agents for cancer therapy.

Reduction-responsive dehydroepiandrosterone prodrug nanoparticles loaded with camptothecin for cancer therapy by enhancing oxidation therapy and cell replication inhibition

The pentose phosphate pathway (PPP) plays a critical role by providing ribulose-5-phosphate (Ru5P) and NADPH for nucleotide synthesis and reduction energy, respectively. Accordingly, blocking the PPP process may be an effective strategy for enhancing oxidation therapy and inhibiting cell replication. Here, we designed a novel reduction-responsive PEGylated prodrug and constructed nanoparticles PsD@CPT to simultaneously deliver a PPP blocker, dehydroepiandrosterone (DHEA), and chemotherapeutic camptothecin (CPT) to integrate amplification of oxidation therapy and enhance cell replication inhibition. Following cellular uptake, DHEA and CPT were released from PsD@CPT in the presence of high glutathione (GSH) levels. As expected, DHEA-mediated reduction level decreases and CPT-induced oxidation level increases synergistically, breaking the redox balance to aggravate cancer oxidative stress. In addition, suppressing nucleotide synthesis by DHEA through the reduction of Ru5P and blocking DNA replication by CPT further motivates a synergistic inhibition effect on tumor cell proliferation. The results showed that PsD@CPT featuring multimodal treatment has satisfactory antitumor activity both in vitro and in vivo. This study provides a new tumor treatment strategy, which combines the amplification of oxidative stress and enhancement of inhibition of cell proliferation based on inhibition of the PPP process.

In vitro study of the trypanocidal activity of anilinophenanthrolines against Trypanosoma cruzi

Chagas disease is present in Latin America, North America, Europe, and Asia, where between 6 and 7 million people are infected. This illness is transmitted mainly by the insect vector during blood feeding and by oral transmission. Chagas disease is treated with benznidazole and its effectiveness depends on which phase of the disease the treatment starts. Therefore, the identification of new compounds with anti-Chagas activities is important. Protozoan parasites present cysteine proteases, important for host cell infection and differentiation, which have been explored as valid targets against pathogenic parasites. In the present study, the effects of 10 new 1,10-phenanthroline derivatives were evaluated on T. cruzi. Three of them were effective against amastigotes (IC₅₀ from 0.5 to 3 μM), epimastigotes (IC₅₀ from 0.5 to at least 10 μM) and trypomastigotes (and LD₅₀ from 1 to 10 μM), and they were not toxic to mammalian cells (CC₅₀ ≥ 20 μM). These compounds also promoted the formation of autophagosomes, alter the level of heterochromatin condensation, caused the loss of kDNA topology, and the elongated cell body shape. Apart from ultrastructural alterations, an increased generation of ROS and decreased mitochondrial membrane potential were observed. Therefore, these drugs revealed potential trypanocidal effects and warrant further antiparasitic studies against Chagas disease.

Anti-proliferative and apoptosis induction activities of curcumin on Leishmania major

Leishmaniasis is a major vector-borne disease triggered by an obligate intracellular protozoan parasite of the genus Leishmania and transmitted by the bite of phlebotomine female sand flies. This parasite causes a wide range of human diseases, from localized self-healing cutaneous lesions to fatal visceral infections. The aim of this study was to investigate the cytotoxic, antiproliferative, and apoptotic effects of curcumin on Leishmania major promastigotes (MHOM/SA/84/JISH) and to assess these effects on the cell cycle of promastigotes. The MTT colorimetric assay was used to evaluate the cytotoxicity and proliferation of promastigotes. Additionally, flow cytometry was used to analyze the cell cycle. The Annexin V/propidium iodide staining technique followed by flow cytometry was used to study the cell death induced by curcumin. In this study curcumin showed a potent antileishmanial effect, exhibiting cytotoxicity against L. major promastigotes. At 80μM, the survival in curcumin treated promastigotes reached 22%; however, the median lethal concentration of curcumin (LC₅₀) was 35μM. The drug exerted its cytotoxic effect by inducing apoptosis. Curcumin-induced cell death in promastigotes reached 82.5% at 80μM concentration. In addition, curcumin delayed the cell cycle in the S-phase inhibiting cell proliferation. Thus, curcumin was shown to be effective against L. major promastigotes. Therefore, curcumin merits further research studies to demonstrate its efficacy in treating cutaneous leishmaniasis.

The HIV - 1 protease inhibitor Amprenavir targets Leishmania donovani topoisomerase I and induces oxidative stress-mediated programmed cell death

The global prevalence of HIV is a major challenge for the control of visceral leishmaniasis. Although the effectiveness and usefulness of amprenavir (APV) are well studied in anti-retroviral regimens, very little is known on HIV/VL-co-infected patients. In the present study, we report for the first time the protective efficacy of APV against visceral leishmaniasis by inhibition of DNA Topoisomerase I (LdTOP1LS) and APV-induced downstream pathway in programmed cell death (PCD). During the early phase of activation, reactive oxygen species (ROS) is increased inside the cells, which causes subsequent elevation of lipid peroxidation. Endogenous ROS formation and lipid peroxidation cause eventual depolarization of mitochondrial membrane potential (ΔΨ_m). Furthermore, the release of cytochrome c and activation of CED3/CPP32 group of proteases lead to the formation of oxidative DNA lesions followed by DNA fragmentation. The promising in vitro and ex vivo results promoted to substantiate further by in vivo animal experiment, which showed a significant reduction of splenic and hepatic parasites burden compared to infected controls. Interestingly, APV selectively targets LdTOPILS and does not inhibit the catalytic activity of human topoisomerase I (hTopI). Moreover, based on the cytotoxicity test APV is not toxic for host macrophage cells, which is correlated with non-responsiveness of inhibition of catalytic activity of hTopI. Taken together, this study provides the opportunity for discovering and evaluating newer potential molecular therapeutic targets for drug designing. The present study might be exploited in future as important therapeutics, which will be useful for treatment of VL as well as HIV-VL co-infection.

The ultimate fate determinants of drug induced cell-death mechanisms in Trypanosomatids

Chemotherapy constitutes a major part of modern-day therapy for infectious and chronic diseases. A drug is said to be effective if it can inhibit its target, induce stress, and thereby trigger an array of cell death pathways in the form of programmed cell death, autophagy, necrosis, etc. Chemotherapy is the only treatment choice against trypanosomatid diseases like Leishmaniasis, Chagas disease, and sleeping sickness. Anti-trypanosomatid drugs can induce various cell death phenotypes depending upon the drug dose and growth stage of the parasites. The mechanisms and pathways triggering cell death in Trypanosomatids serve to help identify potential targets for the development of effective anti-trypanosomatids. Studies show that the key proteins involved in cell death of trypanosomatids are metacaspases, Endonuclease G, Apoptosis-Inducing Factor, cysteine proteases, serine proteases, antioxidant systems, etc. Unlike higher eukaryotes, these organisms either lack the complete set of effectors involved in cell death pathways, or are yet to be deciphered. A detailed summary of the existing knowledge of different drug-induced cell death pathways would help identify the lacuna in each of these pathways and therefore open new avenues for research and thereby new therapeutic targets to explore. The cell death pathway associated complexities in metazoans are absent in trypanosomatids; hence this summary can also help understand the trigger points as well as cross-talk between these pathways. Here we provide an in-depth overview of the existing knowledge of these drug-induced trypanosomatid cell death pathways, describe their associated physiological changes, and suggest potential interconnections amongst them.

Chemo-Protective Potential of Cerium Oxide Nanoparticles against Fipronil-Induced Oxidative Stress, Apoptosis, Inflammation and Reproductive Dysfunction in Male White Albino Rats

Fipronil (FIP) is an insecticide commonly used in many fields, such as agriculture, veterinary medicine, and public health, and recently it has been proposed as a potential endocrine disrupter. The purpose of this study was to inspect the reproductive impacts of FIP and the possible protective effects of cerium nanoparticles (CeNPs) on male albino rats. Rats received FIP (5 mg/kg bwt; 1/20 LD₅₀), CeNPs (35 mg/kg bwt) and FIP+CeNPs per os daily for 28 days. Serum testosterone levels, testicular oxidative damage, histopathological and immunohistochemical changes were evaluated. FIP provoked testicular oxidative damage as indicated by decreased serum testosterone (≈60%) and superoxide dismutase (≈50%), glutathione peroxidase activity (≈46.67%) and increased malondialdehyde (≈116.67%) and nitric oxide (≈87.5%) levels in testicular tissues. Furthermore, FIP induced edematous changes and degeneration within the seminiferous tubules, hyperplasia, vacuolations, and apoptosis in the epididymides. In addition, FIP exposure upregulated interleukin-1β (IL-1β), nitric oxide synthase 2 (NOS), caspase-3 (Casp3) and downregulated the Burkitt-cell lymphomas (BCL-2), inhibin B proteins (IBP), and androgen receptor (Ar) mRNA expressions Casp3, nitric oxide synthase (iNOS), ionized calcium-binding adapter molecule 1(IBA1), and IL-1β immunoreactions were increased. Also, reduction of proliferating cell nuclear antigen (PCNA), mouse vasa homologue (MVH), and SOX9 protein reactions were reported. Interestingly, CeNPs diminished the harmful impacts of FIP on testicular tissue by decreasing lipid peroxidation, apoptosis and inflammation and increasing the antioxidant activities. The findings reported herein showed that the CeNPs might serve as a supposedly new and efficient protective agent toward reproductive toxicity caused by the FIP insecticide in white male rats.

Optimizing autologous bone contribution to implant osseointegration

BACKGROUND

Autologous bone can be harvested from the flutes of a conventional drill or from a bone scraper; here we compared whether autologous bone chips generated by a new slow-speed instrument were more osteogenic than the bone chips generated by conventional drills or bone scrapers. Additionally, we tested whether the osteogenic potential of bone chips could be further improved by exposure to a Wnt signaling (WNT) therapeutic.

METHODS

Osteotomies were prepared in fresh rat maxillary first molar extraction sockets using a conventional drill or a new osseo-shaping instrument; titanium alloy implants were placed immediately thereafter. Using molecular/cellular and histologic analyses, the fates of the resulting bone chips were analyzed. To test whether increasing WNT signaling improved osteogenesis in an immediate post-extraction implant environment, a WNT therapeutic was introduced at the time of implant placement.

RESULTS

Bone collected from a conventional drill exhibited extensive apoptosis; in contrast, bone generated by the new instrument remained in situ, which preserved their viability. Also preserved was the viability of the osteoprogenitor cells attached to the bone chips. Exogenous treatment with a WNT therapeutic increased the rate of osteogenesis around immediate post-extraction implants.

CONCLUSIONS

Compared with conventional drills or bone scrapers, a new cutting instrument enabled concomitant site preparation with autologous bone chip collection. Histology/histomorphometric analyses revealed that the bone chips generated by this new tool were more osteogenic and could be further enhanced by exposure to a WNT therapeutic. Even though gaps still existed in placebo controls and liposomal WNT3A (L-WNT3A) cases, the area of peri-implant bone was significantly greater in L-WNT3A treated sites.

Genotoxic stress-triggered β-catenin/JDP2/PRMT5 complex facilitates reestablishing glutathione homeostasis

The mechanisms underlying how cells subjected to genotoxic stress reestablish reduction-oxidation (redox) homeostasis to scavenge genotoxic stress-induced reactive oxygen species (ROS), which maintains the physiological function of cellular processes and cell survival, remain unclear. Herein, we report that, via a TCF-independent mechanism, genotoxic stress induces the enrichment of β-catenin in chromatin, where it forms a complex with ATM phosphorylated-JDP2 and PRMT5. This elicits histone H3R2me1/H3R2me2s-induced transcriptional activation by the recruitment of the WDR5/MLL methyltransferase complexes and concomitant H3K4 methylation at the promoters of multiple genes in GSH-metabolic cascade. Treatment with OICR-9429, a small-molecule antagonist of the WDR5-MLL interaction, inhibits the β-catenin/JDP2/PRMT5 complex-reestablished GSH metabolism, leading to a lethal increase in the already-elevated levels of ROS in the genotoxic-agent treated cancer cells. Therefore, our results unveil a plausible role for β-catenin in reestablishing redox homeostasis upon genotoxic stress and shed light on the mechanisms of inducible chemotherapy resistance in cancer.

It is known that genotoxic stress induces high levels of ROS and deplete cellular glutathione stores. Here, Cao et al. uncover a β-catenin-dependent TCF/LEF-independent mechanism that promotes histone-mediated transcriptional activation of glutathione synthesis.

Lavandula Luisieri and Lavandula Viridis Essential Oils as Upcoming Anti-Protozoal Agents: A Key Focus on Leishmaniasis

Background and objectives: Leishmania species is the causative agent of leishmaniasis, a broad-spectrum clinical condition that can even be life-threatening when neglected. Current therapeutic strategies, despite beings highly cost-effective, have been increasingly associated with the appearance of drug-resistant microorganisms. Thus, an increasing number of thorough studies are needed towards upcoming drug discovery. This study aims to reveal the anti-protozoa activity of Lavandula luisieri and Lavandula viridis essential oils (EO) and their main components (1,8-cineole, linalool, and borneol). Materials and Methods: L. luisieri and L. viridis EO and their main components’ leishmanicidal effects were tested in vitro against Leishmania infantum, Leishmania major, and Leishmania tropica strains. Cell viability effects were estimated by using the tetrazolium-dye (MTT) colorimetric method, morphological changes were assessed by scanning electron microscopy (SEM) and ultrastructural investigation by transmission electronic microscopy (TEM). Phosphatidylserine externalization, mitochondrial membrane potential (MMP), and cathepsin D activity assessment were also carried out. Finally, cytotoxic activity of the studied matrices was also determined in mammalian cells. Results: Plant-studied EO exhibited prominent anti-Leishmania effects (IC50 = 31–263 µg/mL), with L. luisieri being the most active one. At concentrations corresponding to IC50 values, EO-exposed L. infantum promastigotes suffered marked ultrastructural modifications. The presence of aberrant-shaped cells, mitochondrial and kinetoplast swelling, and autophagosomal structures were the most common evidenced changes. L. luisieri EO exerted its leishmanicidal activity through different mechanisms, but mainly through unleashing apoptosis. Phosphatidylserine externalization, mitochondrial membrane potential loss, and cell-cycle arrest at G(0)/G(1) phase were the most remarkable apoptosis-mediated aspects. Inhibition of cathepsin D activity was also observed. No toxic effects were found on macrophage cells. Conclusions: L. luisieri seems to be an upcoming source of bioactive molecules for leishmaniasis control and to find leading molecules for new drugs formulation against Leishmania infections.

Mitochondria-specific drug release and reactive oxygen species burst induced by polyprodrug nanoreactors can enhance chemotherapy

Cancer cells exhibit slightly elevated levels of reactive oxygen species (ROS) compared with normal cells, and approximately 90% of intracellular ROS is produced in mitochondria. In situ mitochondrial ROS amplification is a promising strategy to enhance cancer therapy. Here we report cancer cell and mitochondria dual-targeting polyprodrug nanoreactors (DT-PNs) covalently tethered with a high content of repeating camptothecin (CPT) units, which release initial free CPT in the presence of endogenous mitochondrial ROS (mtROS). The in situ released CPT acts as a cellular respiration inhibitor, inducing mtROS upregulation, thus achieving subsequent self-circulation of CPT release and mtROS burst. This mtROS amplification endows long-term high oxidative stress to induce cancer cell apoptosis. This current strategy of endogenously activated mtROS amplification for enhanced chemodynamic therapy overcomes the short lifespan and action range of ROS, avoids the penetration limitation of exogenous light in photodynamic therapy, and is promising for theranostics.

Harmine induced apoptosis in Spodoptera frugiperda Sf9 cells by activating the endogenous apoptotic pathways and inhibiting DNA topoisomerase I activity

Harmine, a useful botanical compound, has demonstrated insecticidal activity against some pests. However, harmine's mechanism of action has not been thoroughly elucidated to date. To preliminarily explore harmine's insecticidal mechanisms, the cytotoxicity of harmine against Spodoptera frugiperda Sf9 cells was comprehensively investigated. Our results indicated that harmine induced apoptosis in Sf9 cells, as evidenced by cellular and nuclear morphological changes, DNA laddering and increases in caspase-3-like activities. In addition, activation of the mitochondrial apoptotic pathway by harmine was confirmed by the generation of ROS, opening of mitochondrial permeability transition pores (MPTPs), increase in cytosolic Ca²⁺, changes in mRNA expression levels of genes involved in the mitochondrial apoptotic pathway and increase and release of Cytochrome c. Furthermore, lysosomal membrane permeabilization, release of cathepsin L from the lysosome into the cytosol and cleavage of caspase-3 were also triggered, which indicated that lysosomes were involved in this physiological process. Moreover, the effect of harmine on DNA topoisomerase I activity was investigated by in vivo and molecular docking experiments. These data not only verified that harmine induced apoptosis via comprehensive activation of the mitochondrial and lysosomal pathways and inhibition of DNA topoisomerase I activity in Sf9 cells but also revealed a mechanism of harmine insecticidal functions for pest control.