CASE-DFT Structure Elucidation of Proton-Deficient Chlorodepsidones from the Indonesian Lichen and Structure Revision of Flavicansone.

Biodiscovery efforts in Indonesia have aimed to explore the understudied chemical diversity of its rich lichen flora, seeking to find new products endowed with significant biological properties. The chemical screening of a extract led to selection of this species for further investigation. LC/MS and H NMR-based dereplication pinpointed six chlorodepsidones from the thallus of a sample of this lichen.

Δ-Keto-acid/hydroxy-lactone isomerization in some lichen depsides, depsidones and diphenyl ethers.

In some compounds in lichens, the carboxylic acid is -substituted by an 2-oxoalkyl chain. This particular structure induces the existence of δ-keto-acid ka or hydroxy-lactone hl isomers, clearly identified by their NMR data and chemical properties, such as dehydration, methylation and behaviour in thermal conditions. Internal hydrogen bonding between the carboxylic acid and substituent in the ' position is proposed as an isomerization modulator: an H-bond acceptor (OCH) leads to ka isomers, whereas hl isomers are obtained with an H-bond donor (OH).

Intramolecular transesterification of depsides yields fluorescent 1H-isochromen-1-ones: Application as a chemical probe for lichen determination.

The reactivity of eight purified depsides obtained from six european lichens and that display as 2-oxoalkyl chain in ortho-position of the ester bond was explored. These depsides were found to lead to 1H-Isochromen-1-ones, which exhibit a distinctive blue fluorescence at 365 nm, in the presence of a 10% aqueous solution of KOH. A mechanistic explanation, involving the formation of an enolate intermediate and intramolecular transesterification, was proposed and validated by DFT.

Prodrugs as new therapies against Chagas disease: in vivo synergy between Trypanosoma cruzi proline racemase inhibitors and benznidazole.

Objectives: Chagas disease, caused by the parasitic protozoan Trypanosoma cruzi, affects approximately 6-7 million people worldwide. There are limited available therapies and they exhibit low efficacy, often high toxicity in chronic cases and some drug resistance. In this study, our objective was to develop ester prodrugs that inhibit proline racemase (TcPRAC), a parasitic enzyme previously identified and characterised as a promising target because of its essential role in the parasite's life cycle and virulence, and to test their activity against T.

Irreversible inhibitors of the proline racemase unveil innovative mechanism of action as antibacterial agents against Clostridioides difficile.

Proline racemases (PRAC), catalyzing the l-proline and d-proline interconversion, are essential factors in eukaryotic pathogens such as Trypanosoma cruzi, Trypanosoma vivax, and Clostridioides difficile. If the discovery of irreversible inhibitors of T. cruzi PRAC (TcPRAC) led to innovative therapy of the Chagas disease, no inhibitors of CdPRAC have been discovered to date.