TLC and polarimetric investigation of the oscillatory in-vitro chiral inversion ofl-alanine

Abstract

Summary In recent TLC and polarimetric studies we showed, for the first time, the tendency of profen drugs to undergo spontaneous oscillatory chiral inversion in vitro. Because profen drugs are chiral propionic acid derivatives, we sought other chiral compounds with similar chemical structures and hence a similar tendency to spontaneously change their steric configuration. We have previously demonstrated that L-α-phenylalanine and L-tyrosine also undergo oscillatory in-vitro chiral inversion. We also demonstrated the effect of temperature and mixing on the process, and proposed a detailed model of the oscillator, providing the basis for mechanistic understanding of the oscillatory chiral inversion of these compounds. In this study we focused our attention on L-alanine, another amino acid with a chemical structure formally derived from propionic acid, and, again, by use of TLC and polarimetry, investigated the tendency of L-alanine to undergo oscillatory in-vitro chiral inversion when dissolved in neutral, acidic, and basic solvents. We also studied the effect of temperature and sample mixing. It was confirmed that Lalanine also undergoes chiral inversion. The dynamics of the process are specific to each compound.