Investigating the Antifungal Mechanism of Action of Polygodial by Phenotypic Screening in Saccharomyces cerevisiae.

Polygodial is a "hot" peppery-tasting sesquiterpenoid that was first described for its anti-feedant activity against African armyworms. Using the haploid deletion mutant library of Saccharomyces cerevisiae, a genome-wide mutant screen was performed to shed more light on polygodial's antifungal mechanism of action. We identified 66 deletion strains that were hypersensitive and 47 that were highly resistant to polygodial treatment. Among the hypersensitive strains, an enrichment was found for genes required for vacuolar acidification, amino acid biosynthesis, nucleosome mobilization, the transcription mediator complex, autophagy and vesicular trafficking, while the resistant strains were enriched for genes encoding cytoskeleton-binding proteins, ribosomal proteins, mitochondrial matrix proteins, components of the heme activator protein (HAP) complex, and known regulators of the target of rapamycin complex 1 (TORC1) signaling. WE confirm that polygodial triggers a dose-dependent vacuolar alkalinization and that it increases Ca2+ influx and inhibits glucose-induced Ca2+ signaling. Moreover, we provide evidence suggesting that TORC1 signaling and its protective agent ubiquitin play a central role in polygodial resistance, suggesting that they can be targeted by polygodial either directly or via altered Ca2+ homeostasis.

The effect of prolyl oligopeptidase inhibitors on alpha-synuclein aggregation and autophagy cannot be predicted by their inhibitory efficacy.

Previous studies have shown that prolyl oligopeptidase (PREP) negatively regulates autophagy and increases the aggregation of alpha-synuclein (αSyn), linking it to the pathophysiology of Parkinson's disease. Our earlier results have revealed that the potent small molecular PREP inhibitor KYP-2047 is able to increase autophagy and decrease dimerization of αSyn but other PREP inhibitors have not been systematically studied for these two protein-protein interaction mediated biological functions of PREP. In this study, we characterized these effects for 12 known PREP inhibitors with IC50-values ranging from 0.2 nM to 1010 nM. We used protein-fragment complementation assay (PCA) to assess αSyn dimerization and Western Blot of microtubule-associated protein light chain 3B II (LC3B-II) and a GFP-LC3-RFP expressing cell line to study autophagy. In addition, we tested selected compounds in a cell-free αSyn aggregation assay, native gel electrophoresis, and determined the compound concentration inside the cell by LC-MS. We found that inhibition of the proteolytic activity of PREP did not predict decreased αSyn dimerization or increased autophagy, and we also confirmed that this result did not simply reflect concentration differences of the compounds inside the cell. Thus, PREP ligands regulate the effect of PREP on autophagy and αSyn aggregation through a conformational stabilization of the enzyme that is not equivalent to inhibiting its proteolytic activity.

Efforts towards an On-Target Version of the Groebke-Blackburn-Bienaymé (GBB) Reaction for Discovery of Druglike Urokinase (uPA) Inhibitors.

Target-guided synthesis (TGS) has emerged as a promising strategy in drug discovery. Although reported examples of TGS generally involve two-component reactions, there is a strong case for developing target-guided versions of three-component reactions (3CRs) because of their potential to deliver highly diversified druglike molecules. To this end, the Groebke-Blackburn-Bienaymé reaction was selected as a model 3CR. We recently reported a series of druglike urokinase inhibitors, and these serve as reference compounds in the present study. Due to the limited number of literature reports on target-guided 3CRs, multiple experimental parameters were optimized here. Most challenging was the formation of imine intermediates under near-physiological conditions. This aspect was addressed by exploring chemical imine stabilization strategies. Notably, imines are also crucial intermediates of other 3CRs. Such systematic studies are strongly required for further development of the TGS domain but are largely absent in the literature. Hence, this work is intended as a reference for future multicomponent-based TGS studies.

Crystal structure of 5-benzyl-8-bromo-2-meth-yl-1,3-oxazolo[4,5-c][1,8]naphthyridin-4(5H)-one.

The title compound, C17H12BrN3O2, was unexpectedly isolated during an attempt to synthesize pyridodiazepinediones and identified as an oxazolonaphthyridinone derivative. The almost planar oxazolonaphthyridinone ring (r.m.s. deviation = 0.016 Å) makes a dihedral angle of 61.6 (2)° with the phenyl ring. In the crystal, columns of mol-ecules stacked along the a axis are formed by π-π inter-actions between the six-membered rings of the oxazolonaphthyridone moieties [centroid-to-centroid distances = 3.494 (2)-3.906 (3) Å], which further inter-act through C-H⋯π contacts with the phenyl rings.

The orthorhombic pseudopolymorph of tacrine hydrochloride.

Crystallization of tacrine hydrochloride, an acetylcholinesterase inhibitor used during treatment of mild to moderate Alzheimer's disease, from a water:ethanol solution has resulted in an orthorhombic pseudopolymorph. This orthorhombic form which occurs as a dihydrate shows columns of stacking acridines together with continuous Cl-Owater-Owater-Cl chains and ladder-like ribbons composed of squares and hexagons.

Practical preparation of challenging amides from non-nucleophilic amines and esters under flow conditions.

A fast and efficient protocol for the formation of amides from low nucleophilic amines and esters in flow is described. Products were obtained in good to excellent yields and with the advantage of simultaneous mixing of all reagents at once, avoiding steps for intermediate formation. The protocol is also suitable to be combined with ester synthesis, resulting in the preparation of amides in-line from haloarenes.

Scaffold hopping via a transannular rearrangement-encompassing cascade.

A novel reaction cascade for converting benzodiazepinediones into oxazoloquinolinones using carboxylic acid anhydrides in the presence of base has been developed using flow methods. Products are obtained in yields up to 98%.