Minor groove binders for DNA synthesised at the University of Strathclyde (S-MGBs) have been successfully shown to be active against a wide range of infectious organisms including bacteria, fungi, and parasites in particular through collaborations with a worldwide network of partners. S-MGBs can be obtained from a wide range of structures and physicochemical properties that influence the S-MGB’s effect on a given class of target organism. A dominant feature that determines selectivity is access of the S-MGB to the DNA of the target organism which requires passing through the external cell membrane or cell wall and any further intracellular barriers. For infectious organisms that reside inside the host mammalian cell, passage through the mammalian cell membrane must also occur. Experiments have shown that S-MGBs containing alkene links in place of an amide are in general most effective against all the infective agents studied but significant activity against some fungi has also been observed in S-MGBs with amidine links. More subtle effects in anti-fungal activity have also been observed relating to the structure of the fungal cell wall: dicationic S-MGBs were active against C. neoformans, which lacks phosphate esters in its outer cell wall, but inactive against C. albicans, whose cell wall contains phosphate esters to which the dicationic S-MGB can bind thereby preventing cell penetration. Comparison of toxicity with mammalian cells shows significant but not optimal selectivity indices for the best compounds. In the case of M. tuberculososis, improved selectivity indices were obtained using non-ionic surfactant vesicles in the formulation. Together these results are helpful to identify clusters of S-MGBs that can be optimised to be selective against a given infectious agent.

Leishmaniases are a complex of tropical and sub-tropical diseases caused by parasites of the genus Leishmania and transmitted by the bite of an insect vector, the sandfly. Quinolines of natural origin have shown interesting antileishmanial activities on several experimental leishmaniasis models. A classical daily treament with 2-n-propylquinoline (2-n-PQ) on five consecutive days in mice model is not sufficient to cure the mice infected with Leishmania donovani and the activity requires a 10-day treatment duration whatever the route (oral, parenteral) because of a short half-life elimination of the drug.

Therefore, 2-n-PQ derivatives were bound to soluble polysaccharides to improve their solubility, delay their elimination half-life and therefore enhance the activity. In vitro release at 37ºC in phosphate buffer was performed in various conditions and showed that around 65% of the compound was released in 24 h. In vitro, the most active conjugate was the dextran-2PQA conjugate exhibiting an IC₅₀ value at 12 µg/mL on Leishmania donovani intramacrophage amastigotes. However, this system did not allow a sufficient release of the active principle explaining the lack of in vivo activity.

Another approach consisted in administering 2-n-PQ intravenously. Two systems were successful both in vitro and in vivo : a liposomal formulation named 2-n-PQ-LIP and a hydroxypropyl beta-cyclodextrin inclusion complex designated as 2-n-PQ-HPC. The most interesting one was the liposomal formulation, active on the L. donovani Balb/c mouse model, by reducing the parasite burden by more than 80% after an intravenous treatment regimen of 3 mg equivalent 2-n-PQ/kg/day given on five consecutive days. No synergistic activity between 2-n-PQ and Amphotericin B was monitored either in vitro or in vivo.

These formulations should be studied further on other leishmaniasis models and for toxicological considerations.

Acknowledgements

This work was supported by a grant from the Indo-French Centre of Advanced Research, New Delhi (CEFIPRA) (No. 4803-04) and Kaluvu Balaraman was recipient of a CEFIPRA postdoctoral fellowship.

Our research group focuses on the synthesis of thiazolo[5,4-f]quinazolin-9(8H)-one derivatives as potential kinase inhibitors involved in Alzheimer's disease.[1] Previous in vitro results led us to intensively study the backbone for further SAR investigations. In order to establish SAR studies, C-H arylation methods were investigated. [2] The regioselective C-H bond activation of the thiazole moieties was developed to furnish the corresponding valuable C2-arylated compounds.

Herein, we report an extension of this methodology to thiazolo[5,4-f]quinazolin-9(8H)-ones in order to functionalize regioselectively at C2 and C7 positions.[3] A metal-free synthesis of the tricyclic starting material was also described giving access to these compounds in a facile manner.[4] Two monoarylated compounds show high inhibition values for kinases of the DYRK's family,  involved in Alzheimer's disease.

[1]    (a) Chaikuad, A.; Diharce, J.; Schröder, M.. Foucourt, A.; Leblond, B.; Casagrande, A.-S.; Désiré, L.; Bonnet, P.; Knapp, S.; Besson, T. J. Med. Chem. 2016, 59, 10315; (b) Hédou, D.; Dubouilh-Benard, C.; Loaëc, N.; Meijer, L.; Fruit, C.; Besson, T. Molecules 2016, 21, 794; (c) Courtadeur, S.; Benyamine, H.; Delalonde, L.; de Oliveira, C.; Leblond, B.; Foucourt, A.; Besson, T.; Casagrande, A.-S.; Taverne, T.; Girard, A.; Pando, M.P.; Désiré, L. J. Neurochem. 2015, 133, 440; (d) Thompson, B.; Bhansali, R.; Diebold, L.; Cook, D. E.; Stolzenburg, L.;Casagrande, A. –S.; Besson, T.; Leblond, B.; Desire, L.; Malinge, S.; Crispino, J. D. J. Exp. Med. 2015, 212, 723.

[2]    (a) Laclef, S.; Harari, M.; Godeau, J.; Schmitz-Afonso, I.; Bischoff, L.; Hoarau, C.; Levacher, V.; Fruit, C.; Besson, T. Org. Lett. 2015, 17, 1700 ; (b) Godeau, J.; Harari, M.; Laclef, S.; Deau, E.; Fruit, C.; Besson, T. Eur. J. Org. Chem. 2015, 7705.

[3]    Harari, M.; Couly, F.; Fruit, C.; Besson, T. Org. Lett. 2016, 18, 3282.

[4]    Couly, F.; Dubouilh-Benard, C.; Besson, T.; Fruit, C. Synthesis 2017, in press, DOI: 10.1055/s-0036-1588434.

The challenge of antimicrobial resistance is well understood and extensive research is underway worldwide to find effective, new antibacterial agents that will be less susceptible to the emergence of resistance than those of previous generations. The challenge of combining potency with resilience is unlikely to be met using the standard medicinal chemistry paradigm of single drug, single target, single effect. Our approach using specially designed minor groove binders for DNA (Strathclyde MGBs), whilst formally attacking a single molecular target, in practice disrupts many biological processes such that the emergence of resistance can be expected to be low. The first example of this approach to reach the clinic, MGB-BP-3, is highly effective against Gram positive bacteria and has been successfully taken through a Phase 1 clinical trial for the treatment of Clostridium difficile infections by our development partner, MGB Biopharma. Mechanism of action studies with S. aureus as the target organism have provided evidence consistent with the expectation. RNAseq experiments have shown that there are substantial changes in gene expression, some upregulated and others downregulated, such that the bacterium faces multiple metabolic challenges to its survival. In particular processes associated with cell wall integrity and energy production are affected, the latter being consistent with the steep dose response kill curve observed with this type of drug. Moreover attempts to generate resistant strains have failed. Taken together, these properties identify Strathclyde minor groove binders as significant new compounds in the fight against antibacterial resistance.

Carvedilol is one of the most used cardiovascular drugs, highly metabolized by CYP450 2D6, 1A2, 2C9. Fluvoxamine, an antidepressant agent, is a moderate/potent inhibitor of these enzymes. There is the risk of drug-drug interaction when these two drugs are concomitantly administered. The aim of this study was to investigate the drug-drug interactions between carvedilol and fluvoxamine in vitro and in rats.

There were two periods: reference and test. In the first period each rat received an oral dose of 3.57 mg/kg body weight [b.w.] carvedilol.  In the test period, carvedilol was administered after a pre-treatment with multiple oral doses of fluvoxamine (14.28 mg/kg b.w.). HPLC-MS was the device used to determine the plasma concentration of carvedilol. The PK parameters were calculated by non-compartmental analysis. Rat liver microsomal incubation systems were used to investigate the effect of fluvoxamine on the metabolic rate of carvedilol.

Fluvoxamine co-administered with carvedilol can change the PK parameters (increase AUC, t_1/2, decrease the Cl). In vitro experiment showed that fluvoxamine decreased the metabolic rate of carvedilol.

The present study demonstrated the pharmacokinetic drug-drug interaction between carvedilol and fluvoxamine in vitro and in vivo. Fluvoxamine significantly influenced the pharmacokinetic of carvedilol, due to its capacity of CYP2D6 and CYP1A2 inhibition. As a result of this interaction the exposure to carvedilol was significantly increased. This is the reason why co-administration of carvedilol and fluvoxamine needs precaution.

Malaria is a neglected tropical disease that remains a leading cause of morbidity and mortality among the world’s poorest populations. More than 100 tropical and sub-tropical countries are endemic for this infectious disease. Pregnant women and children are the most sensitive to this infection and, in 2015, 429 000 people died. Among the five species of Plasmodium responsible for human malaria, P. falciparum is the parasite which causes the most serious form of the disease. More recent efforts focused on the development of antimalarial vaccines and since 2001, World Health Organization (WHO) recommends artemisinin-based combination therapies (ACTs). In drugs resistance areas, several antimalarial drugs, such as aminoalcohol-aryl (mefloquine (MQ), lumefantrine (LM)), are currently used in combination with artemisinin derivatives. However, the emergence of multi-drug-resistant parasites decreases efficacy of ACTs. Thus, the design of new active compounds on Plasmodium-resistant strains is urgent.
We have previously developed an asymmetric synthesis to prepare 4-aminoalcohol-quinoline enantiomers (AQ) as MQ analogs. They were active on nanomolar range against 3D7 (chloroquine-sensitive) and W2 (chloroquine-resistant) P. falciparum strains. Interestingly, (S)-enantiomers displayed an activity increased by 2 to 15-fold as compared to their (R)-counterparts. During the Plasmodium intra-erythrocytic asexual stages, hemozoin formation and the oxidative and glutathione-dependent degradation of heme are inhibited by these aminoalcohol-aryls (MQ, LM). Currently, their mechanisms of actions are not totally clear and remain to be explored.
In continuation of our work, we are interested to study the change of heterocycle (fluorene vs quinoline) on the antimalarial activity. We focus on the design and the preparation of novel racemic and enantiopure aminoalcohol-fluorene derivatives (AFM) as LM analogs. The evaluation of their antiplasmodial activity against P. falciparum and their corresponding cytotoxicity is under progress.

The design of novel and efficient compounds fighting against the highly variable RNA viruses, such as hepatitis C virus (HCV), is a major goal. RNA oligonucleotides have gained great interest as specific molecular tools for inhibiting essential viral processes. The combination of different RNA molecules with proven antiviral activity, each with its own activity and specificity, into a single molecule yields the so-called multivalent compounds, which are promising candidates for the development of new therapeutic strategies. These compounds are chimeric entities with enhanced therapeutic properties. In this work, the previously developed chimeric inhibitor RNA HH363-10 was used as archetype for the development of improved anti-HCV inhibitors. HH363-10 consists of a hammerhead ribozyme domain, targeting the essential internal ribosome entry site (IRES) region in the 5’ end of the HCV genome; and an aptamer RNA molecule, directed against the highly conserved IIIf domain of the IRES. As a result of the application of an in vitro selection process to the RNA pool, which results from the partial randomization of the aptamer-domain sequence of the HH363-10 molecule, 10 new multivalent optimized chimeric antiHCV RNA molecules were selected for further analysis. The aptamer RNA domain was evolved to contain two binding sites: the one mapping the IIIf domain, and a newly acquired targeting site, either to the IRES domain IV (which contains the translation start codon) or the essential linker region between the IRES domains I and II. These chimeric molecules efficiently and specifically interfered with HCV IRES-dependent translation in vitro (with IC50 values in the low µM range). They also inhibited both viral translation and replication in cell culture. These findings highlight the feasibility of using in vitro selection strategies for obtaining improved, multivalent RNA molecules with potential clinical applications.

Reactive carbonyl species (RCS) such as methylglyoxal (MGO) or malondialdehyde (MDA) are endogenously formed during the sugar glycoxidation and lipid peroxidation of polyunsaturated fatty acids induced by oxidative stress exacerbation. Their condensation with amino groups of tissue proteins gives AGE (Advanced Glycation Endproducts) and ALE (Advanced Lipid peroxidation Endproducts). In Alzheimer's disease (AD), extensive AGE/ALE accumulation has been reported in extracellular amyloid β (Aβ) plaques and intracellular tau-associated neurofibrillary tangles. Indeed, a critical imbalance between cerebral reactive oxygen species (ROS) production and endogenous antioxidant capacities associated with biometal dyshomeostasis has been suggested to be a driving force for AD onset and progression. Aβ-oligomers induce oxidative stress whereas transition metals (Zn²⁺, Cu²⁺ and Fe³⁺) stimulate Aβ aggregation and APP (amyloid precursor protein) processing. Consequently, RCS accumulation takes part in the vicious downward redox amyloid spiral leading to neurodegeneration.^1,2 AGE/ALE are now considered to play an important role at the late stages of AD pathogenesis through three main mechanisms.³ First, glycated Aβ cross-linking promotion accelerates its deposition and its protease resistance. Secondly, AGE/ALE formation not only accelerates tau hyperphosphorylation, disturbs the neuronal membrane depolarization process and the glucose transport but also exacerbates glutamate-mediated excitotoxicity. Thirdly, AGE promote via their receptors RAGE oxidative stress and inflammation as well as cell apoptosis.

Taking into account the multifactorial pathogenesis of AD, we designed new multifunctional drugs that are simultaneously able to trap RCS (primary vicinal diamine function) as well as ROS and biometals (phenolic acid or hydroxypyridinone moiety).⁴ In the presentation, synthesis of these new promising hybrid AGE/ALE inhibitors and evaluation of their physicochemical and biological properties (carbonyl trapping capacity, antioxidant activity, Cu²⁺-chelating capacity, cytotoxicity and protective effect against in vitro MGO-induced apoptosis in the model AD cell-line PC12) are reported.

References

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Gold drugs are well known and have been widely studied for their potential chemotherapeutic properties in anticancer treatments, although they have some limitations as for example chemical stability.^1,2

Gold N-heterocyclic carbenes are excellent s-donor ligands and forms extraordinarily stable gold derivatives, and indeed NHC-Au(I) species display high cytotoxicity in vitro (low micromolar to nanomolar) against a variety of human cancer cell lines with different degrees of selectivity. In the search for new alternatives of stable and robust derivatives, not only N-heterocyclic but N-acyclic carbenes could be explored. ^2,3,4

N-acyclic carbenes are easily accessible via the reaction between isocyanide gold compounds and different amines (Scheme 1). The reaction between one of those derivatives with different thiol groups, in presence of K₂CO₃, as deprotonating agent, has led to a family of gold(I) NAC thiolate derivatives with high cytotoxicity (Scheme 2).

Scheme 1- Reactions between isocyanide gold(I) compounds and different amines.

Scheme 2 - Reaction between compound 4 and different thiol derivatives.

Biological activity was measured by the MTT assay for different human cancer cell lines: A-549 (lung cancer) and MiaPaca2 (pancreatic cancer) for the different synthetized compounds, calculating their IC₅₀. The IC₅₀ values found are in the very low micromolar range and this means an excellent start point for future the development of these compounds as anticancer drugs.

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¹ B. Bertrand, A. Casini, Dalton Trans., 2014, 43, 4209.

² B. Bertrand, A. Citta, I. L. Franken, M. Picquet, A. Folda, V. Scalcon, M. P. Rigobello ,  P. Le Gendre, A. Casini, E. Bodio. J. Biol. Inorg. Chem., 2015, 20, 1005–1020.

³ O. Dada, D. Curran, C. O'Beirne, H. Müller-Bunz, X. Zhu, M. Tacke. J. Organomet. Chem. 2017, 840, 30-37.

⁴ W. Liu, R. Gust.  Coord. Chem. Revs., 2016, 329, 191-213.

Antibiotic resistance is an emerging disease and a real problem of health. Resistance of Gram negative bacteria such as Acinetobacter baumannii and Escherichia coli to conventional antibiotics lead to therapeutic failure and require new antibiotherapies. The use of the iron transport systems is one of the most promising strategies to overcome this resistance phenomenon. These specific routes of entry, essential for the survival of the microorganisms, allow ferric siderophore complexes to carry iron within the bacteria.

These systems allow the introduction of antibacterial agents (conjugates antibiotic-siderophore) or toxic complexes (gallium complexes) into the bacteria to kill them. Rhodotorulic acid (RA) is a siderophore transported by TonBox dependant Fhu receptors. These kinds of receptors are expressed by Acinetobacter baumannii and Escherichia coli. RA is dioxopiperazine iron chélater with hydroxamate as iron ligands and two asymmetric centers (S,S configuration). This spatial orientation is essential for the Fhu receptors recognition.

We have previously reported the asymmetric synthesis of 3-substituted 2-oxopiperazines. Herein, we present an original and a convergent strategy to synthesize RA and corresponding 3,6-disubstituted analogues. Siderophore-like test and measurement of the complexing strength of these compounds will be carried out.