Generation of Cannabigerolic Acid Derivatives and Their Precursors by Using the Promiscuity of the Aromatic Prenyltransferase NphB.

NphB is an aromatic prenyltransferase with high promiscuity for phenolics including flavonoids, isoflavonoids, and plant polyketides. It has been demonstrated that cannabigerolic acid is successfully formed by the reaction catalysed by NphB using geranyl diphosphate and olivetolic acid as substrates. In this study, the substrate specificity of NphB was further determined by using olivetolic acid derivatives as potential substrates for the formation of new synthetic cannabinoids. The derivatives differ in the hydrocarbon chain attached to C6 of the core structure. We performed in silico experiments, including docking of olivetolic acid derivatives, to identify differences in their binding modes. Substrate acceptance was predicted. Based on these results, a library of olivetolic acid derivatives was constructed and synthesized by using different organic synthetic routes. Conversion was monitored in in vitro assays with purified NphB versions. For the substrates leading to a high conversion olivetolic acid-C8, olivetolic acid-C2 and 2-benzyl-4,6-dihydroxybenzoic acid, the products were further elucidated and identified as cannbigerolic acid derivatives. Therefore, these substrates show potential to be adapted in cannabinoid biosynthesis.

Discovery of an Unexpected Similarity in Ligand Binding between BRD4 and PPARγ.

Knowledge about interrelationships between different proteins is crucial in fundamental research for the elucidation of protein networks and pathways. Furthermore, it is especially critical in chemical biology to identify further key regulators of a disease and to take advantage of polypharmacology effects. Here, we present a new concept that combines a scaffold-based analysis of bioactivity data with a subsequent screening to identify novel inhibitors for a protein target of interest. The initial scaffold-based analysis revealed a flavone-like scaffold that can be found in ligands of different unrelated proteins indicating a similarity in ligand binding. This similarity was further investigated by testing compounds on bromodomain-containing protein 4 (BRD4) that were similar to known ligands of the other identified protein targets. Several new BRD4 inhibitors were identified and proven to be validated hits based on orthogonal assays and X-ray crystallography. The most important discovery was an unexpected relationship between BRD4 and peroxisome-proliferator activated receptor gamma (PPARγ). Both proteins share binding site similarities near a common hydrophobic subpocket which should allow the design of a polypharmacology-based ligand targeting both proteins. Such dual-BRD4-PPARγ modulators open up new therapeutic opportunities, because both are important drug targets for cancer therapy and many more important diseases. Thereon, a complex structure of sulfasalazine was obtained that involves two bromodomains and could be a potential starting point for the design of a bivalent BRD4 inhibitor.

What can be inferred from moiré patterns? A case study of trimesic acid monolayers on graphite.

Self-assembly of benzene-1,3,5-tricarboxylic acid (trimesic acid - TMA) monolayers at the alkanoic acid-graphite interface is revisited. Even though this archetypal model system for hydrogen bonded porous networks is particularly well studied, the analysis of routinely observed superperiodic contrast modulations known as moiré patterns lags significantly behind. Fundamental questions remain unanswered such as, are moiré periodicity and orientation always the same, i.e. is exclusively only one specific moiré pattern observed? What are the geometric relationships (superstructure matrices) between moiré, TMA, and graphite lattices? What affects the moiré pattern formation? Is there any influence from solvent, concentration, or thermal treatment? These basic questions are addressed via scanning tunneling microscopy experiments at the liquid-solid interface, revealing a variety of different moiré patterns. Interestingly, TMA and graphite lattices were always found to be ∼5° rotated with respect to each other. Consequently, the observed variation in the moiré patterns is attributed to minute deviations (<2°) from this preferred orientation. Quantitative analysis of moiré periods and orientations facilitates the determination of the TMA lattice parameter with picometer precision.

Solvent-free on-surface synthesis of boroxine COF monolayers.

A protocol is proposed for the solvent-free on-surface synthesis of covalent organic framework monolayers by condensation of diboronic acids. Monomers are vapor-deposited and water is used for equilibrium regulation. Samples are characterized on progressively smaller length scales by light microscopy, Scanning Electron Microscopy, and Scanning Tunneling Microscopy.