Effects of Plasmodium falciparum-infected erythrocytes on matrix metalloproteinase-9 regulation in human microvascular endothelial cells.

Abstract Objective To investigate the regulation of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in human microvascular endothelium (HMEC-1) exposed to erythrocytes infected by different strains of Plasmodium falciparum (P. falciparum). Methods HMEC-1 cells were co-incubated for 72 h with erythrocytes infected by late stage trophozoite of D10 (chloroquine-sensitive) or W2 (chloroquine-resistant) P. falciparum strains. Cell supernatants were then collected and the levels of pro- or active gelatinases MMP-9 and MMP-2 were evaluated by gelatin zymography and densitometry. The release of pro-MMP-9, MMP-3, MMP-1 and TIMP-1 proteins was analyzed by western blotting and densitometry. Results Infected erythrocytes induced de novo proMMP-9 and MMP-9 release. Neither basal levels of proMMP-2 were altered, nor active MMP-2 was found. MMP-3 and MMP-1 secretion was significantly enhanced, whereas basal TIMP-1 was unaffected. All effects were similar for both strains. Conclusions P. falciparum parasites, either chloroquine-sensitive or -resistant, induce the release of active MMP-9 protein from human microvascular endothelium, by impairing balances between proMMP-9 and its inhibitor, and by enhancing the levels of its activators. This work provides new evidence on MMP involvement in malaria, pointing at MMP-9 as a possible target in adjuvant therapy

Antiplasmodial activity of p-substituted benzyl thiazinoquinone derivatives and their potential against parasitic infections

Malaria is a life-threatening disease and, what is more, the resistance to available antimalarial drugs is a recurring problem. The resistance of Plasmodium falciparum malaria parasites to previous generations of medicines has undermined malaria control efforts and reversed gains in child survival. This paper describes a continuation of our ongoing efforts to investigate the effects against Plasmodium falciparum strains and human microvascular endothelial cells (HMEC-1) of a series of methoxy p-benzyl-substituted thiazinoquinones designed starting from a pointed antimalarial lead candidate. The data obtained from the newly tested compounds expanded the structure-activity relationships (SARs) of the thiazinoquinone scaffold, indicating that antiplasmodial activity is not affected by the inductive effect but rather by the resonance effect of the introduced group at the para position of the benzyl substituent. Indeed, the current survey was based on the evaluation of antiparasitic usefulness as well as the selectivity on mammalian cells of the tested p-benzyl-substituted thiazinoquinones, upgrading the knowledge about the active thiazinoquinone scaffold

Development of nature inspired antiplasmodial hits possessing the thiazinoquinone pharmacophore

Malaria accounts globally for more than 200 million new cases and 438,000 deaths per year. Since malaria is a disease of worldwide implications, combating it is one of the highest priority programs of the WHO. A worrisome increase in the number of fatal cases has been registered in recent years and it is principally due to the diffusion of multi-drug resistant strains of Plasmodium, making less effective the limited armamentarium of available drugs. Therefore, there is an urgent need of new antimalarial drugs with high efficacy against resistant strains and broad stage mode of action. To reach these challenging aims, the identification and selection of new lead compounds constitutes a crucial point. In this regard, nature remains an ever evolving resource. Recently, the antiplasmodial activity of marine secondary metabolites characterized by a quinone scaffold has been reported. In particular, it is worth to point out that a number of quinones have been shown to be effective antimalarials. The observed effects are most likely related to the most prominent chemical feature of these kind of molecules, that is their ability to undergo redox reaction i) shuttling electrons from reduced flavoproteins to acceptors such as hemoglobin-associated or free Fe(III)-protoporphyrin IX or ii) inhibiting the mitochondrial electron transport chain. In this context, recently, we were inspired by two marine metabolites Aplidinone A and B isolated from the Mediterranean ascidian Aplidium conicum, and we developed a series of synthetic analogues featuring the thiazinoquinone chemotype present in the natural metabolites with simplified side chains and different substituents. Manipulation of this chemical scaffold afforded additional analogues with improved pharmacological proprieties compared to the starting hits identified in the previous series

Synthesis and antiplasmodial activity of novel bioinspired imidazolidinedione derivatives

Malaria is an enormous threat to public health, due to the emergence of Plasmodium falciparum resistance to widely-used antimalarials, such as chloroquine (CQ). Current antimalarial drugs are aromatic heterocyclic derivatives, most often containing a basic component with an added alkyl chain in their chemical structure. While these drugs are effective, they have many side effects. This paper presents the synthesis and preliminary physicochemical characterisation of novel bioinspired imidazolidinedione derivatives, where the imidazolidinedione core was linked via the alkylene chain and the basic piperazine component to the bicyclic system. These compounds were tested against the asexual stages of two strains of P. falciparum—the chloroquine-sensitive (D10) and chloroquine-resistant (W2) strains. In parallel, in vitro cytotoxicity was investigated on a human keratinocyte cell line, as well as their hemolytic activity. The results demonstrated that the antiplasmodial effects were stronger against the W2 strain (IC50 between 2424.15–5648.07 ng/mL (4.98–11.95 µM)), compared to the D10 strain (6202.00–9659.70 ng/mL (12.75–19.85 µM)). These molecules were also non-hemolytic to human erythrocytes at a concentration active towards the parasite, but with low toxicity to mammalian cell line. The synthetized derivatives, possessing enhanced antimalarial activity against the CQ-resistant strain of P. falciparum, appear to be interesting antimalarial drug candidates

Investigating the antiparasitic potential of the marine sesquiterpene avarone, its reduced form avarol, and the novel semisynthetic thiazinoquinone analogue thiazoavarone

The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the thiazinoquinone derivative thiazoavarone. The semisynthetic compound, as well as the natural metabolites avarone and avarol, were pharmacologically investigated in order to assess their antiparasitic properties against sexual and asexual stages of Plasmodium falciparum, larval and adult developmental stages of Schistosomamansoni (eggs included), and also against promastigotes and amastigotes of Leishmania infantum and Leishmania tropica. Furthermore, in depth computational studies including density functional theory (DFT) calculations were performed. A toxic semiquinone radical species which can be produced starting both from quinone- and hydroquinone-based compounds could mediate the anti-parasitic effects of the tested compounds

Supplementary material for the article: Manzano, J. I.; Konstantinović, J.; Scaccabarozzi, D.; Perea, A.; Pavić, A.; Cavicchini, L.; Basilico, N.; Gamarro, F.; Šolaja, B. A. 4-Aminoquinoline-Based Compounds as Antileishmanial Agents That Inhibit the Energy Metabolism of Leishmania. European Journal of Medicinal Chemistry 2019, 180, 28–40. https://doi.org/10.1016/j.ejmech.2019.07.010

Supplementary material for: [https://doi.org/10.1016/j.ejmech.2019.07.010]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/3287

Supplementary data for the article: Konstantinović, J.; Videnović, M.; Orsini, S.; Bogojević, K.; D’Alessandro, S.; Scaccabarozzi, D.; Terzić Jovanović, N.; Gradoni, L.; Basilico, N.; Šolaja, B. A. Novel Aminoquinoline Derivatives Significantly Reduce Parasite Load in Leishmania Infantum Infected Mice. ACS Medicinal Chemistry Letters 2018, 9 (7), 629–634. https://doi.org/10.1021/acsmedchemlett.8b00053

Supplementary material for: [https://pubs.acs.org/doi/10.1021/acsmedchemlett.8b00053]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2209]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2948

MS Dereplication for Rapid Discovery of Structurally New or Novel Natural Products

In order to accelerate the isolation and characterisation of structurally new or novel natural products, it is crucial to develop efficient strategies that prioritise samples with greatest promise early in the workflow so that resources can be utilised in a more efficient and cost-effective manner. Two complementary approaches have been developed: One is based on targeted identification of known compounds held in a database based on high resolution MS and predicted LC retention time data [1]. The second is an MS metrics-based approach where the software algorithm calculates metrics for sample novelty, complexity, and diversity after interrogating databases of known compounds, and contaminants. These metrics are then used to prioritise samples for isolation and structure elucidation work [2]. Both dereplication approaches have been validated using natural product extracts resulting in the isolation and characterization of new or novel natural products