Facing Diseases Caused by Trypanosomatid Parasites: Rational Design of Pd and Pt Complexes With Bioactive Ligands

Human African Trypanosomiasis (HAT), Chagas disease or American Trypanosomiasis (CD), and leishmaniases are protozoan infections produced by trypanosomatid parasites belonging to the kinetoplastid order and they constitute an urgent global health problem. In fact, there is an urgent need of more efficient and less toxic chemotherapy for these diseases. Medicinal inorganic chemistry currently offers an attractive option for the rational design of new drugs and, in particular, antiparasitic ones. In this sense, one of the main strategies for the design of metal-based antiparasitic compounds has been the coordination of an organic ligand with known or potential biological activity, to a metal centre or an organometallic core. Classical metal coordination complexes or organometallic compounds could be designed as multifunctional agents joining, in a single molecule, different chemical species that could affect different parasitic targets. This review is focused on the rational design of palladium(II) and platinum(II) compounds with bioactive ligands as prospective drugs against trypanosomatid parasites that has been conducted by our group during the last 20 years.

The Influence of Different Carbonate Ligands on the Hydrolytic Stability and Reduction of Platinum(IV) Prodrugs

Pt(IV) complexes bearing axial carbonate linkages have drawn much attention recently. A synthetic method behind it allows to attach the hydroxyl group of bioactive ligands to the available hydroxyl group...

Selenosemicarbazone Metal Complexes as Potential Metal-based Drugs

The discovery of the anticancer activity of cisplatin has marked the emergence of modern Inorganic Medicinal Chemistry. This field of research is concerned with the application of inorganic compounds to therapy or diagnosis of disease. In particular, metal coordination of bioactive ligands has gained recognition in drug design. The interaction between transition metal ions and the organic drugs could enhance their diagnostic and therapeutic potentials by improving the stability and/or bioavailability or by achieving a metal-drug synergism through a dual or multiple mechanism of action. The isosteric replacement of sulfur by selenium in thiosemicarbazones leads to selenosemicarbazones. This class of compounds exhibit numerous biological activities like antitumor, antimicrobial, antiviral etc. and, in most cases, they were more pronounced in comparison to the sulfur analogues. On the other hand, while the effect of transition metal complexation on the biological activity of thiosemicarbazones has been widely studied, the pharmacological activity of the corresponding metal-selenosemicarbazone compounds has been less explored. In this work, the most relevant results related to the selenosemicarbazone metal complexes as potential metal-based drugs have been reviewed.

Computational Atom-based Three-Dimensional Quantitative Structure-Activity Relationship (3D QSAR) Model for Predicting Anti-Dengue Agents

Dengue fever is a viral infection spread by the female mosquito Aedes aegypti. It is a virus spread by mosquitoes found all over the tropics with risk levels varying depending on rainfall, relative humidity, temperature and urbanization. There are no specific medications that can be used to treat the condition. The development of possible bioactive ligands to combat Dengue fever before it becomes a pandemic is a global priority. Few studies on building three-dimensional quantitative structure-activity relationship (3D QSAR) models for anti-dengue agents have been reported. Thus, we aimed at building a statistically validated atom-based 3D-QSAR model using bioactive ligands reported to possess significant anti-dengue properties. In this study, the Schrodinger PhaseTM atom-based 3D QSAR model was developed and was validated using known anti-dengue properties as ligand data. This model was also tested to see if there was a link between structural characteristics and anti-dengue activity of a series of 3-acyl-indole derivatives. The established 3D QSAR model has strong predictive capacity and is statistically significant [Model: R2 Training Set = 0.93, Q2 (R2 Test Set) = 0.72]. In addition, the pharmacophore characteristics essential for the reported anti-dengue properties were explored using combined effects contour maps (coloured contour maps: blue: positive potential and red: negative potential) of the model. In the pathway of anti-dengue drug development, the model could be included as a virtual screening method to predict novel hits.

Anticancer Activity of Half-Sandwich Ru, Rh and Ir Complexes with Chrysin Derived Ligands: Strong Effect of the Side Chain in the Ligand and Influence of the Metal

An important challenge in the field of anticancer chemotherapy is the search for new species to overcome the resistance of standard drugs. An interesting approach is to link bioactive ligands to metal fragments. In this work, we have synthesized a set of p-cymene-Ru or cyclopentadienyl-M (M = Rh, Ir) complexes with four chrysin-derived pro-ligands with different -OR substituents at position 7 of ring A. The introduction of a piperidine ring on chrysin led to the highly cytotoxic pro-ligand HL4 and its metal complexes L4-M (SW480 and A549 cell lines, cytotoxic order: L4-Ir > L4-Ru ≈ L4-Rh). HL4 and its complexes induce apoptosis and can overcome cis-platinum resistance. However, HL4 turns out to be more cytotoxic in healthy than in tumor cells in contrast to its metal complexes which displayed higher selectivity than cisplatin towards cancer cells. All L4-M complexes interact with double stranded DNA. Nonetheless, the influence of the metal is clear because only complex L4-Ir causes DNA cleavage, through the generation of highly reactive oxygen species (1O2). This result supports the hypothesis of a potential dual mechanism consisting of two different chemical pathways: DNA binding and ROS generation. This behavior provides this complex with a great effectivity in terms of cytotoxicity.

Potential Anti-Proliferative, Anti-Inflammatory and Anti-Viral Components from Sinopodophyllum Hexandrum Explored Using Bio-Affinity Ultrafiltration with Multiple Drug Targets

Background: Sinopodophyllum hexandrum (S. hexandrum) is a typical Chinese herbal medicine with numerous components and remarkable pharmacological activities. However, the specific phytochemicals responsible for its anti-proliferative, anti-inflammatory and anti-viral effects remain unexplored.Methods: The integrated analytical strategy combining bio-affinity ultrafiltration with multiple drug targets was developed to rapidly screen and identify bioactive ligands from S. hexandrum. The in vitro anti-proliferative and COX-2 inhibitory assays of bioactive ligands screened were further verified by sulforhodamine B (SRB) cell proliferation and cytotoxicity detection and COX-2 inhibitor screening kits, respectively. Molecular docking analysis was also implemented by the AutoDockTools 1.5.6 software.Results: 10, 7, 9 and 9 phytochemicals were screened out and identified as the potential Topo I, Topo II, COX-2 and ACE2 ligands, respectively. Hereinto, podophyllotoxin and quercetin with higher EF values displayed strong inhibitory effects on A549 and HT-29 cells comparable with etoposide and 5-FU. Furthermore, compared with indomethacin at 0.73 ± 0.07 mM, podophyllotoxin and kaempferol with higher EF values exerted stronger inhibitory effects with IC50 values at 0.36 ± 0.02 mM and 10.49 ± 0.61 mM, respectively. Additionally, the optimal binding sites and mode of action between bioactive ligands and multiple drug targets were determined by molecular docking. Wherein, isorhamnetin showed a stronger affinity to ACE2 with the binding energy of -5.72 kcal/mol and the IC50 value at 63.95 mM, lower than MLN-4760 (-4.27 kcal/mol and 738.62 mM). Conclusions: The integrative strategy combining multiple drug targets and bio-affinity ultrafiltration LC-MS in the present study showed very promising potential for the quick screening and identifying bioactive ligands in S. hexandrum for Topo I, Topo II, COX-2 and ACE2, and some bioactive compounds screened out from this work were verified with other in vitro assays, and even better than those positive drugs of interest. Based on these findings, we then first constructed an interacting network among multi-components and multi-targets. In this way, we showcased a quick and reliable experimental strategy for uncovering the underlying mechanism of the empirical traditional applications of S. hexandrum which could also provide valuable information for better understanding the therapeutic targets and therapeutic ligands of other herbal medicines.

Recent Progresses in Conjugation with Bioactive Ligands to Improve the Anticancer Activity of Platinum Compounds

: Platinum (Pt) drugs, including cisplatin, are widely used for the treatment of solid tumors. Despite the clinical success, side effects and occurrence of resistance represent major limitations to the use of clinically available Pt drugs. To overcome these problems, a variety of derivatives have been designed and synthetized. Here, we summarize the recent progress in the development of Pt(II) and Pt(IV) complexes with bioactive ligands. The development of Pt(II) and Pt(IV) complexes with targeting molecules, clinically available agents, and other bioactive molecules is an active field of research. Even if none of the reported Pt derivatives has been yet approved for clinical use, many of these compounds exhibit promising anticancer activities with an improved pharmacological profile. Thus, planning hybrid compounds can be considered as a promising approach to improve the available Pt-based anticancer agents and to obtain new molecular tools to deepen the knowledge of cancer progression and drug resistance mechanisms.