Capturing and releasing cucurbitacins with α, β-unsaturated group from Cucumis melo based on reversibility of thia-Michael addition reaction

Abstract

Molecules containing α, β-unsaturated carbonyl structure have gained constant attention because of their potential of interacting with nucleophilic amino acid residues and further protein function regulating. However, current methods for finding and isolating such compounds are challenged by lacking of convenience and orientation. Herein we introduce a new strategy for capturing and releasing natural products with α, β-unsaturated group by regulating the direction of thia-Michael addition reaction. Target molecules could be separated from various impurities by means of controlling the association and dissociation with hydrophilic small sulfhydryl molecules and consequently change of polarity and solubleness. Our strategy showed effectiveness that natural products containing α, β-unsaturated esters and ketones could be successfully released from the adducts with cysteine. Finally, nine cucurbitacins with target functional group from the extract of Cucumis melo were enriched and isolated with high selectivity. This strategy may thus help to isolate natural products with α, β-unsaturated group in complex samples.