Synthesis and biological evaluation of thiazolidinedione derivatives with high ligand efficiency to P. aeruginosa PhzS

The thiazolidinone ring is found in compounds that have widespan biology activity and there is mechanism-based evidence that compounds bearing this moiety inhibit P. aeruginosa PhzS (PaPzhS), a key enzyme in the biosynthesis of the virulence factor named pyocyanin. Ten novel thiazolidinone derivatives were synthesised and screened against PaPhzS, using two orthogonal assays. The biological results provided by these and 28 other compounds, whose synthesis had been described, suggest that the dihydroquinazoline ring, found in the previous hit (A- Kd = 18 µM and LE = 0.20), is not required for PaPzhS inhibition, but unsubstituted nitrogen at the thiazolidinone ring is. The molecular simplification approach, pursued in this work, afforded an optimised lead compound (13- 5-(2,4-dimethoxyphenyl)thiazolidine-2,4-dione) with 10-fold improvement in affinity (Kd= 1.68 µM) and more than 100% increase in LE (0.45), which follows the same inhibition mode as the original hit compound (competitive to NADH).Executive summaryPhzS is a key enzyme in the pyocyanin biosynthesis pathway in P. aeruginosa.Orthogonal assays (TSA and FITC) show that fragment-like thiazolidinedione derivatives bind to PaPhzS with one-digit micromolar affinity.Fragment-like thiazolidinedione derivatives bind to the cofactor (NADH) binding site in PaPhzS.The molecular simplification optimised the ligand efficiency and affinity of the lead compound.

A new and recyclable system based on tropin ionic liquids for resolution of several racemic amino acids

A new, recyclable solid-liquid resolution system was developed based on tropin ionic liquids [C_nDTr][L-Pro]₂ for the enantiomeric resolution of racemic phenylalanine and other α-substituted carboxylic acids including tryptophan, tyrosine, benzene glycine and mandelic acid. With racemic phenylalanine as resolution model, effect factors were investigated for better resolution conditions. On the conditions, some efficient resolution were achieved, for instance the e.e. (98%) and product yield (76%) in solid phase for phenylalanine, and the e.e. 99.71% in solid phase for tryptophan. Chiral product was verified with fourier transform infrared spectroscopy (FT-IR), Raman spectrum, thermal gravity analysis (TG), elemental analysis (EA) and chiral HPLC. Further, the resolution mechanism was studied with computer molecular dynamic simulations and UV-vis. The resolution was closely related to the formation of complexes (L-Phe-Cu(Ⅱ)-L-pro^-) and the spatial configuration of D/L-Phe. The system is characteristic of high resolution, no organic solvent, easy isolation of solid-liquid and recycle of all chemical materials as much as possible.