Multivalent pyrrolidines acting as pharmacological chaperones against Gaucher disease

A concise asymmetric synthesis of clickable enantiomeric pyrrolidines was achieved using Crabbé-Ma allenation. The synthesized iminosugars were grafted by copper-free strain-promoted alkyne-azide cycloaddition onto phosphorus dendrimers. The hexavalent and dodecavalent pyrrolidines were evaluated as β-glucocerebrosidase inhibitors. The level of inhibition suggests that monofluorocyclooctatriazole group may contribute to the affinity for the protein leading to potent multivalent inhibitors. Docking studies were carried out to rationalize these results. Then, the iminosugars clusters were evaluated as pharmacological chaperones in Gaucher patients' fibroblasts. An increase in β-glucocerebrosidase activity was observed with hexavalent and dodecavalent pyrrolidines at concentrations as low as 1 µM and 0.1 µM, respectively. These iminosugar clusters constitute the first example of multivalent pyrrolidines acting as pharmacological chaperones against Gaucher disease.

Synthesis of enantioenriched 2,2-disubstituted pyrrolidines via sequential asymmetric allylic alkylation and ring contraction

The synthesis of a variety of enantioenriched 2,2-disubstituted pyrrolidines is described. A stereogenic quaternary center is first formed utilizing an asymmetric allylic alkylation reaction of a benzyloxy imide, which can then be reduced to a chiral hydroxamic acid. This compound can then undergo a thermal "Spino" ring contraction to afford a carbamate protected 2,2-disubstituted pyrrolidine stereospecifically. These pyrrolidines can be further advanced to enantioenriched indolizidine compounds. This reaction sequence allows access to new molecules that could be useful in the development of pharmaceutical agents.

Synthesis of Nitrone-derived Pyrrolidine Scaffolds and Their Combinatorial Libraries to Develop Selective α-l-Rhamnosidase Inhibitors

A general and flexible approach toward the development of α-l-rhamnosidase (α-l-Rha-ase) inhibitors is described. Five enantiopure poly-substituted pyrrolidine-based scaffolds bearing the C1-aminomethyl moiety were designed and synthesized from five-membered cyclic nitrones. Each structurally diversified amide library of these scaffolds was rapidly generated via combinatorial parallel synthesis and applied for in-situ inhibition study against α-l-Rha-ase, allowing us to efficiently identify new inhibition hits. Surprisingly, all promising inhibitors are derived from the same scaffold 3. Among them, the most potent and selective inhibitor is pyrrolidine 19 with Ki =0.24 μM, approximately 24-fold more potent than the reference compound DAA (Ki =5.7 μM). It is the first study to comprehensively prepare pyrrolidine-based scaffolds and libraries for inhibition study against α-l-Rha-ase.

Phosphine-Catalyzed Enantioselective (3+2) Annulation of Vinylcyclopropanes with Imines for the Synthesis of Chiral Pyrrolidines

A phosphine-catalyzed highly enantioselective and diastereoselective (up to 98 % ee and >20 : 1 dr) (3+2) annulation between vinylcyclopropanes and N-tosylaldimines has been developed, which allows facile access to a range of highly functionalized chiral pyrrolidines. Notably, this method makes use of vinylcyclopropanes as a synthon for phosphine-mediated asymmetric annulation reaction, which will offer new opportunities for potential applications of cyclopropanes substrates in phosphine-catalyzed organic transformations.

Tandem construction of biological relevant aliphatic 5-membered N-heterocycles

Nature often uses cascade reactions in a highly stereocontrolled manner for assembly structurally diverse nitrogen-containing heterocyclic scaffolds, i.e. secondary metabolites, important for medicinal chemistry and pharmacy. Five-membered nitrogen-containing heterocycles as standalone rings, as well as spiro and polycyclic systems are pharmacophores of drugs approved in various therapies, i.a. antibacterial or antiviral, antifungal, anticancer, antidiabetic, as they target many key enzymes. Furthermore, a large number of pyrrolidine derivatives are currently considered as drug candidates. Cascade transformations, also known as domino or tandem reactions, offer straightforward methods to build N-heterocyclic libraries of the great structural variety desired for drawing SAR conclusions. The tandem transformations are often atom economic and time-saving because they are performed as the one-pot, so no need for purification after each 'virtual' step and the limited necessity of protective groups are characteristic for these processes. Thus, the same results as in classical multistep synthesis can be achieved at markedly lower costs and shorter time, which is in line with modern green chemistry rules. Great advantage of cascade reactions is often reflected in their high regio- and stereoselectivities, enabling the preparing of the heterocyclic compound better fitted to the expected target in cells. This review reveals the biological relevance of N-heterocyclic scaffolds based on saturated 5-membered rings since we showed a number of examples of approved drugs together with the recent biologically attractive leading structures of drug candidates. Next, novel cascade synthetic procedures, taking into account the structure of the reactants and reaction mechanisms, enabling to obtain biological-relevant heterocyclic frameworks with good yields and relatively high stereoselectivity, were reviewed and compared. The review covers the advances of designing biological active N-heterocycles mainly from 2018 to 2021, whereas the synthetic part is focused on the last 7 years.

A review upon medicinal perspective and designing rationale of DPP-4 inhibitors

Type 2 Diabetes Mellitus (T2DM) is one of the highly prevalence disorder and increasing day by day worldwidely. T2DM is a metabolic disorder, which is characterized by deficiency in insulin or resistance to insulin and thus increases the glucose levels in the blood. Various approaches are there to treat diabetes but still there is no cure for this disease. DPP-4 inhibitor is a privileged target in the field of drug discovery and provides various opportunities in exploring this target for development of molecules as antidiabetic agents. DPP-4 acts by inhibiting the incretin action and thus decreases the level of blood glucose by imparting minimal side effects. Sitagliptin, vildagliptin, linagliptin etc. are the different DPP-4 based drugs approved throughout the world for the treatment of diabetes mellitus. Cyanopyrrolidines, triazolopiperazine amide, pyrrolidines are basic core nucleus present in various DPP-4 inhibitors and has potential effects. In the past few years, researchers had applied various approaches to synthesize potent DPP-4 inhibitors as antidiabetic agent without side effects like weight gain, cardiovascular risks, retinopathy etc. This review will also emphasize the recent strategies and rationale utilized by researchers for the development of DPP-4 inhibitors. This review also reveals about the various other approaches like molecular modelling, ligand based drug designing, high throughput screening etc. are used by the various research group for the development of potential DPP-4 inhibitors.

Broad spectrum antimicrobial activity of dispirooxindolopyrrolidine fused acenaphthenone heterocyclic hybrid against healthcare associated microbial pathogens (HAMPs)

BACKGROUND

Healthcare-associated infections (HAI) are prime health task worldwide and issue of patient safety besides intensifying antimicrobial drug resistance. It is essential to formulate structurally fascinating novel, active and cost-effective anti-microbial drugs possessing a peculiar way of action and capable of overcoming the resistance to effectively combat this disease.

MATERIALS AND METHODS

The synthesized spiro-heterocyclic hybrids (SHHs) were elucidated through spectroscopic analysis and were assessed for their in vitro antimicrobial activity by agar diffusion method and minimal inhibitory concentration (MIC) value was also determined. In addition, antioxidant potential was also evaluated through DPPH radical scavenging assays.

RESULTS

The novel class of SHHs 4a and 4b displayed significant antibacterial activity against selected healthcare associated microbial pathogens (HAMPs). In addition, SHH 4b showed potent antioxidant properties.

CONCLUSION

Antibacterial and antifungal activity of dispirooxindolopyrrolidine fused acenaphthenone heterocyclic hybrids were examined. Interestingly, SHH 4b exhibited potent antimicrobial activity against selected HAMPs. Further, these compounds were also showed potent antioxidant properties. These results revealed that SHH 4b is a promising lead for the development of new antimicrobial drugs.

Synthesis of novel 2-pyrrolidinone and pyrrolidine derivatives and study of their inhibitory activity against autotaxin enzyme

Autotaxin (ATX), a glycoprotein (~125 kDa) isolated as an autocrine motility factor from melanoma cells, belongs to a seven-membered family of ectonucleotide pyrophosphatase/phosphodiesterase (ENPP), and exhibits lysophospholipase D activity. ATX is responsible for the hydrolysis of lysophosphatidylcholine (LPC) to produce the bioactive lipid lysophosphatidic acid (LPA), which is upregulated in a variety of pathological inflammatory conditions, including fibrosis, cancer, liver toxicity and thrombosis. Given its role in human disease, the ATX-LPA axis is an interesting target for therapy, and the development of novel potent ATX inhibitors is of great importance. In the present work a novel class of ATX inhibitors, optically active derivatives of 2-pyrrolidinone and pyrrolidine heterocycles were synthesized. Some of them exhibited interesting in vitro activity, namely the hydroxamic acid 16 (IC₅₀ 700 nM) and the carboxylic acid 40b (IC₅₀ 800 nM), while the boronic acid derivatives 3k (IC₅₀ 50 nM), 3l (IC₅₀ 120 nM), 3 m (IC₅₀ 180 nM) and 21 (IC₅₀ 35 nM) were found to be potent inhibitors of ATX.

Exploring substituent diversity on pyrrolidine-aryltriazole iminosugars: Structural basis of β-glucocerebrosidase inhibition

The synthesis of a library of pyrrolidine-aryltriazole hybrids through CuAAC between two epimeric dihydroxylated azidomethylpyrrolidines and differently substituted phenylacetylenes is reported. The evaluation of the new compounds as inhibitors of lysosomal β-glucocerebrosidase showed the importance of the substitution pattern of the phenyl moiety in the inhibition. Crystallization and docking studies revealed key interactions of the pyrrolidine motif with aminoacid residues of the catalytic site while the aryltriazole moiety extended along a hydrophobic surface groove. Some of these compounds were able to increase the enzyme activity in Gaucher patient fibroblasts, acting as a new type of chemical chaperone for Gaucher disease.

Harnessing pyrrolidine iminosugars into dimeric structures for the rapid discovery of divalent glycosidase inhibitors

The synthesis of three libraries (1a-l, 1a'-l' and 2a-l) of dimeric iminosugars through CuAAC reaction between three different alkynyl pyrrolidines and a set of diazides was carried out. The resulting crude dimers were screened in situ against two α-fucosidases (libraries 1a-l and 1a'-l') and one β-galactosidase (2a-l). This method is pioneer in the search of divalent glycosidase inhibitors. It has allowed the rapid identification of dimer 1i as the best inhibitor of α-fucosidases from bovine kidney (K_i = 0.15 nM) and Homo sapiens (K_i = 60 nM), and dimer 2e as the best inhibitor of β-galactosidase from bovine liver (K_i = 5.8 μM). In order to evaluate a possible divalent effect in the inhibition, the synthesis and biological analysis of the reference monomers were also performed. Divalent effect was only detected in the inhibition of bovine liver β-galactosidase by dimer 2e.

Nickel and Palladium Catalysis in the Stereoselective Synthesis of Functionalized Pyrrolidines: Enantioselective Formal Synthesis of (+)-α-Allokainic Acid

Neuroexcitatory natural products are accessible from 1 via the intermediate 2, which is obtained by Ni-catalyzed cyclization, transposition of the protecting group, and Pd-catalyzed reduction with allylic transposition. This stepwise formation of stereocenters allows a highly direct and stereoselective synthesis of the excitatory amino acid (+)-α-allokainic acid, which displays an all-trans arrangement of the substituents about the pyrrolidine ring. TBS=tert-butyldimethylsilyl.