Concise asymmetric synthesis of new enantiomeric C-alkyl pyrrolidines acting as pharmacological chaperones against Gaucher disease.

A concise and asymmetric synthesis of the enantiomeric pyrrolidines 2 and ent-2 are herein reported. Both enantiomers were assessed as ß-GCase inhibitors. While compound ent-2 acted as a poor competitive inhibitor, its enantiomer 2 proved to be a potent non-competitive inhibitor. Docking studies were carried out to substantiate their respective protein binding mode. Both pyrrolidines were also able to enhance lysosomal ß-GCase residual activity in N370S homozygous Gaucher fibroblasts. Notably, the non-competitive inhibitor 2 displayed an enzyme activity enhancement comparable to that of reference compounds IFG and NN-DNJ. This work highlights the impact of inhibitors chirality on their protein binding mode and shows that, beyond competitive inhibitors, the study of non-competitive ones can lead to the identification of new relevant parmacological chaperones.

Alsinol, an arylamino alcohol derivative active against Plasmodium, Babesia, Trypanosoma, and Leishmania: past and new outcomes.

Malaria, babesiosis, trypanosomosis, and leishmaniasis are some of the most life-threatening parasites, but the range of drugs to treat them is limited. An effective, safe, and low-cost drug with a large activity spectrum is urgently needed. For this purpose, an aryl amino alcohol derivative called Alsinol was resynthesized, screened in silico, and tested against Plasmodium, Babesia, Trypanosoma, and Leishmania. In silico Alsinol follows the Lipinski and Ghose rules. In vitro it had schizontocidal activity against Plasmodium falciparum and was able to inhibit gametocytogenesis; it was particularly active against late gametocytes. In malaria-infected mice, it showed a dose-dependent activity similar to chloroquine. It demonstrated a similar level of activity to reference compounds against Babesia divergens, and against promastigotes, and amastigotes stages of Leishmania in vitro. It inhibited the in vitro growth of two African animal strains of Trypanosoma but was ineffective in vivo in our experimental conditions. It showed moderate toxicity in J774A1 and Vero cell models. The study demonstrated that Alsinol has a large spectrum of activity and is potentially affordable to produce. Nevertheless, challenges remain in the process of scaling up synthesis, creating a suitable clinical formulation, and determining the safety margin in preclinical models.

Alkyne-Tagged Analogue of Jaspine†B: New Tool for Identifying Jaspine†B Mode of Action.

The first biologically relevant clickable probe related to the antitumor marine lipid jaspine B is reported. The concise synthetic route to both enantiomers relied on the supercritical fluid chromatography (SFC) enantiomeric resolution of racemic materials. The eutomeric dextrogyre derivative represents the first jaspine B analogue with enhanced cytotoxicity with IC50 down to 30 nm. These enantiomeric probes revealed a chiralitydependent cytoplasmic imaging of U2OS cancer cells by in situ click labeling.

Synthesis, Spectroelectrochemical Behavior, and Chiroptical Switching of Tris(ß-diketonato) Complexes of Ruthenium(III), Chromium(III), and Cobalt(III).

Five tris(ß-diketonato) complexes of ruthenium(III), chromium(III), and cobalt(III) [Ru(Buacac)3 (1), Ru(Oacac)3 (2), Cr(Buacac)3 (3), Cr(Oacac)3 (4), and Co(Buacac)3 (5), where Buacac = 3-butylpentane-2,4-dionato and Oacac = 3-octylpentane-2,4-dionato] with a chiral propeller-like structure have been prepared. Ligands and complexes syntheses are presented together with characterization of the compounds by 1H and 13C NMR spectroscopy, mass spectrometry, IR, UV-vis, electronic circular dichroism (ECD) spectroscopy, electrochemistry studies, and first-principles calculations. The crystal structures of 1 and 5 have also been obtained and analyzed. A comparison of the 1H NMR spectra of diamagnetic (ligands and 5) and paramagnetic (1 and 2) species is presented. Optical resolution of the five complexes has been achieved for the first time by supercritical fluid chromatography using a chiral column, giving rise to very high purity grades in all cases. ECD measurements and calculations have led to the assignment of the absolute configuration, Δ or Λ, of each enantiomer for 1-5. Spectroelectrochemical UV-vis and ECD studies have been performed on ruthenium Λ-2 and chromium Λ-4 complexes, revealing their redox-triggered chiroptical switching confirming the noninnocence character of the ß-diketonate ligands.

Asymmetric synthesis and biological evaluation of natural or bioinspired cytotoxic C2-symmetrical lipids with two terminal chiral alkynylcarbinol pharmacophores.

Bidirectional syntheses of C2-symmetrical lipids embedding two terminal alkynylcarbinol pharmacophores are reported. Naturally occurring chiral alkenylalkynylcarbinol units were generated using Pu's procedure for enantioselective addition of terminal alkynes to aldehydes, allowing the first asymmetric synthesis of (3R,4E,16E,18R)-icosa-4,16-diene-1,19-diyne-3,18-diol, isolated from Callyspongia pseudoreticulata. Two synthetic analogues embedding the recently uncovered (S)-dialkynylcarbinol pharmacophore were secured using Carreira's procedure adapted to ynal substrates. The dramatic effect of the carbinol configuration on cytotoxicity was confirmed with submicromolar IC50 values against HCT116 cells.

Coumarin-poly(2-oxazoline)s as synergetic and protein-undetected nanovectors for photodynamic therapy.

Because of the difficult challenges of nanopharmaceutics, the development of a variety of nanovectors is still highly desired. Photodynamic therapy, which uses a photosensitizer to locally produce reactive oxygen species to kill the undesired cells, is a typical example for which encapsulation has been shown to be beneficial. The present work describes the use of coumarin-functionalized polymeric nanovectors based on the self-assembly of amphiphilic poly(2-oxazoline)s. Encapsulation of pheophorbide a, a known PDT photosensitizer, is shown to lead to an increased efficiency compared to the un-encapsulated version. Interestingly, the presence of coumarin both enhances the desired photocytotoxicity and enables the crosslinking of the vectors. Various nanovectors are examined, differing by their size, shape and hydrophilicity. Their behaviour in PDT protocols on HCT-116 cells monolayers is described, the influence of their crosslinking commented. Furthermore, the formation of a protein corona is assessed.

Phenyl dialkynylcarbinols, a Bioinspired Series of Synthetic Antitumor Acetylenic Lipids.

A series of 25 chiral anti-cancer lipidic alkynylcarbinols (LACs) were devised by introducing an (hetero)aromatic ring between the aliphatic chain and the dialkynylcarbinol warhead. The resulting phenyl-dialkynylcarbinols (PACs) exhibit enhanced stability, while retaining cytotoxicity against HCT116 and U2OS cell lines with IC50 down to 40 nM for resolved eutomers. A clickable probe was used to confirm the PAC prodrug behavior: upon enantiospecific bio-oxidation of the carbinol by the HSD17B11 short-chain dehydrogenase/reductase (SDR), the resulting ynones covalently modify cellular proteins, leading to endoplasmic reticulum stress, ubiquitin-proteasome system inhibition, and apoptosis. Insights into the design of LAC prodrugs specifically bioactivated by HSD17B11 vs its paralogue HSD17B13 were obtained. The HSD17B11/HSD17B13-dependent cytotoxicity of PACs was exploited to develop a cellular assay to identify specific inhibitors of these enzymes. A docking study was performed with the HSD17B11 AlphaFold model, providing a molecular basis of the SDR substrates mimicry by PACs. The safety profile of a representative PAC was established in mice.

A mesoporous metal-organic framework used to sustainably release copper(ii) into reducing aqueous media to promote the CuAAC click reaction.

The mesoporous metal-organic framework Cr-MIL-101-NH2 (MOF1) has been used to encapsulate, by a simple impregnation method, large amounts of copper sulfate. The resulting loaded material, Cu@MOF1, was successfully employed to slowly release copper(ii) into an appropriate reaction medium in which the reducing agent sodium ascorbate reduces copper(ii) to copper(i), thus allowing the well-known copper(i)-catalyzed alkyne-azide cycloaddition (CuAAC) "click" reaction to proceed in the absence of potentially high local copper(i) concentrations. The use of a MOF-based controlled copper release system such as Cu@MOF1 may be relevant for copper(i)-catalyzed reactions having substrates that could be degraded by potentially high local concentrations of copper(i). The copper chelating ligand TBTA (tris(benzyltriazolylmethyl)amine), a very useful ligand for click chemistry, has been successfully attached to the pores of MOF1. The resulting TBTA-functionalized MOF (MOF3) was compared with its non-functionalized version (MOF1). At copper loadings of ca. 3 mmol g-1, the results revealed that the performances of the two materials are strikingly similar. Upon immersion in methanol/water (95/5) containing sodium ascorbate, both materials slowly released copper encapsulated in their pores and could be recovered and reused efficiently for up to five reaction cycles without reloading with metal ion, while allowing the CuAAC reaction to proceed with excellent conversion rates and yields.

Characterization of a sucrose/starch matrix through positron annihilation lifetime spectroscopy: unravelling the decomposition and glass transition processes.

The triplet state of positronium, o-Ps, is used as a probe to characterize a starch-20% w/w sucrose matrix as a function of temperature (T). A two-step decomposition (of sucrose, and then starch) starts at 440 K as shown by a decrease in the o-Ps intensity (I(3)) and lifetime (τ(3)), the latter also disclosing the occurrence of a glass transition. Upon sucrose decomposition, the matrix acquires properties (reduced size and density of nanoholes) that are different from those of pure starch. A model is successfully established, describing the variations of both I(3) and τ(3) with T and yields a glass transition temperature, T(g) = (446 ± 2) K, in spite of the concomitant sucrose decomposition. Unexpectedly, the starch volume fraction (as probed through thermal gravimetry) decreases with T at a higher rate than the free volume fraction (as probed through PALS).

Isolation and identification of ten new sildenafil derivatives in an alleged herbal supplement for sexual enhancement.

A sexual enhancer dietary supplement in pre-commercialization phase was analyzed. It contained the two phosphodiesterase-5 inhibitors (PDE-5i) sildenafil and methisosildenafil as major adulterants. Fourteen more sildenafil derivatives were detected and after isolation, their structures were elucidated thanks to NMR, high resolution and tandem mass spectrometry, and UV spectroscopy. Ten of them were never described. All these compounds are probably by-products of different reaction steps during the synthesis of the two PDE-5i that were not properly eliminated during the purification procedure. The total amount of sildenafil-related compounds was estimated at 68 mg per capsule, sildenafil and methisosildenafil accounting for 20 mg and 38 mg respectively.

Methinylogation Approach in Chiral Pharmacophore Design: from Alkynyl- to Allenyl-carbinol Warheads against Tumor Cells.

Extension of a structure-activity relationship study of the antitumor cytotoxicity of lipidic dialkynylcarbinols (DACs) is envisaged by formal methinylogation of one of the ethyndiyl moieties of the DAC warhead into the corresponding allenylalkynylcarbinol (AllAC) counterpart. External AllACs were directly obtained by methinylation of the parent DACs with formaldehyde in either the racemic or scalemic series. Isomers containing external progargyl and propynyl motifs were also prepared. Internal AllACs were obtained as racemic statistical mixtures of stereoisomers in two steps from the key C5 -DAC rac-TIPS-C≡C-CH(OH)-C≡CH and aldehydes. Kinetic resolution of the (S)-C5 -DAC in 97 % ee and (R)-C5 -DAC in 99 % ee was achieved by sequential lipase-mediated acetylation/hydrolysis using the Candida antartica lipase (Novozyme 435). The four internal AllAC stereoisomers were prepared by asymmetric methinylation with (R)- or (S)-diphenylprolinol as chiral auxiliary. Cytotoxicity assays on HCT116 cancer cells showed that the most active (eutomeric) external or internal AllAC exhibits an S configuration, a fatty chain length of n=12, and a 50 % inhibitory concentration IC50 ≈1.0 µm.

Structure-activity relationship of new antimalarial 1-aryl-3-susbtituted propanol derivatives: Synthesis, preliminary toxicity profiling, parasite life cycle stage studies, target exploration, and targeted delivery.

Design, synthesis, structure-activity relationship, cytotoxicity studies, in silico drug-likeness, genotoxicity screening, and in vivo studies of new 1-aryl-3-substituted propanol derivatives led to the identification of nine compounds with promising in vitro (55, 56, 61, 64, 66, and 70-73) and in vivo (66 and 72) antimalarial profiles against Plasmodium falciparum and Plasmodium berghei. Compounds 55, 56, 61, 64, 66 and 70-73 exhibited potent antiplasmodial activity against chloroquine-resistant strain FCR-3 (IC50s < 0.28 µM), and compounds 55, 56, 64, 70, 71, and 72 showed potent biological activity in chloroquine-sensitive and multidrug-resistant strains (IC50s < 0.7 µM for 3D7, D6, FCR-3 and C235). All of these compounds share appropriate drug-likeness profiles and adequate selectivity indexes (77 < SI < 184) as well as lack genotoxicity. In vivo efficacy tests in a mouse model showed compounds 66 and 72 to be promising candidates as they exhibited significant parasitemia reductions of 96.4% and 80.4%, respectively. Additional studies such as liver stage and sporogony inhibition, target exploration of heat shock protein 90 of P. falciparum, targeted delivery by immunoliposomes, and enantiomer characterization were performed and strongly reinforce the hypothesis of 1-aryl-3-substituted propanol derivatives as promising antimalarial compounds.

A shear-induced network of aligned wormlike micelles in a sugar-based molecular gel. From gelation to biocompatibility assays.

A new low molecular weight hydrogelator with a saccharide (lactobionic) polar head linked by azide-alkyne click chemistry was prepared in three steps. It was obtained in high purity without chromatography, by phase separation and ultrafiltration of the aqueous gel. Gelation was not obtained reproducibly by conventional heating-cooling cycles and instead was obtained by shearing the aqueous solutions, from 2 wt% to 0.25 wt%. This method of preparation favored the formation of a quite unusual network of interconnected large but thin 2D-sheets (7nm-thick) formed by the association side-by-side of long and aligned 7nm diameter wormlike micelles. It was responsible for the reproducible gelation at the macroscopic scale. A second network made of helical fibres with a 10-13nm diameter, more or less intertwined was also formed but was scarcely able to sustain a macroscopic gel on its own. The gels were analysed by TEM (Transmission Electronic Microscopy), cryo-TEM and SAXS (Small Angle X-ray Scattering). Molecular modelling was also used to highlight the possible conformations the hydrogelator can take. The gels displayed a weak and reversible transition near 20°C, close to room temperature, ascribed to the wormlike micelles 2D-sheets network. Heating over 30°C led to the loss of the gel macroscopic integrity, but gel fragments were still observed in suspension. A second transition near 50°C, ascribed to the network of helical fibres, finally dissolved completely these fragments. The gels showed thixotropic behaviour, recovering slowly their initial elastic modulus, in few hours, after injection through a needle. Stable gels were tested as scaffold for neural cell line culture, showing a reduced biocompatibility. This new gelator is a clear illustration of how controlling the pathway was critical for gel formation and how a new kind of self-assembly was obtained by shearing.

Exploring the scope of new arylamino alcohol derivatives: Synthesis, antimalarial evaluation, toxicological studies, and target exploration.

Synthesis of new 1-aryl-3-substituted propanol derivatives followed by structure-activity relationship, in silico drug-likeness, cytotoxicity, genotoxicity, in silico metabolism, in silico pharmacophore modeling, and in vivo studies led to the identification of compounds 22 and 23 with significant in vitro antiplasmodial activity against drug sensitive (D6 IC50 ≤ 0.19 µM) and multidrug resistant (FCR-3 IC50 ≤ 0.40 µM and C235 IC50 ≤ 0.28 µM) strains of Plasmodium falciparum. Adequate selectivity index and absence of genotoxicity was also observed. Notably, compound 22 displays excellent parasitemia reduction (98 ± 1%), and complete cure with all treated mice surviving through the entire period with no signs of toxicity. One important factor is the agreement between in vitro potency and in vivo studies. Target exploration was performed; this chemotype series exhibits an alternative antimalarial mechanism.

Design, synthesis and evaluation of new GEQ derivatives as inhibitors of InhA enzyme and Mycobacterium tuberculosis growth.

A series of fluorene-based derivatives was synthesized and evaluated for inhibiting both InhA and Mycobacterium tuberculosis growth. These compounds were inspired by the previously reported Genz-10850 molecule, a good InhA inhibitor, but with a poor activity against M. tuberculosis growth. Structure-activity relationships were performed by introducing the following chemical modifications: 1) the piperazine ring; 2) the amide group; 3) the aryl moiety; and 4) the fluorene moiety. Among these new derivatives, one of them was more effective against both the InhA activity and mycobacterial growth, compared to the hit compound. Docking studies were also performed to rationalize activities of these derivatives. Furthermore, we showed for the first time that efflux pump inhibitors potentiated the efficacy of Genz-10850 (GEQ) derivatives against M. tuberculosis growth, demonstrating that these compounds could be substrates of some efflux pumps.

Identification of chiral alkenyl- and alkynylcarbinols as pharmacophores for potent cytotoxicity.

Illumination by acetylene: Systematic structural variations in a series of archetypal acetylenic lipids derived from the naturally occurring (S,E)-icos-4-en-1-yn-3-ol allowed the discovery of a series of 3R-like 1,4-di-unsaturated carbinol units with a significant and systematic enantiomeric effect on cytotoxicity.