Efficient Stereochemical Analysis of Hydroxy Fatty Acids Using PGME and PAME Derivatization

We present a time-efficient and cost-effective approach for the stereochemical analysis of α- and β-hydroxy fatty acids (α-HFAs and β-HFAs) using chiral derivatizing agents, phenylglycine methyl ester (PGME) and phenylalanine methyl ester (PAME). Conventional methods for stereochemical analysis, such as X-ray crystallography and Mosher's ester derivatization, require pure samples and are laborious. In contrast, PGME and PAME derivatization enables direct LC-MS analysis of crude extracts without compound isolation or extensive sample preparation. Additionally, this method eliminates the need for NMR measurement and crystallization after the reaction, thereby reducing the overall analysis time. The approach was successfully applied to newly discovered lipopeptides, demonstrating its efficiency, reproducibility, and potential for widespread use in the stereochemical characterization of bioactive natural products.