Electrospray tandem mass spectrometry for the structural characterization of p-coumaric acid–oligo(3-hydroxybutyrate) conjugates

• Conjugates of p-coumaric acid with oligo(3-hydroxybutyrate) were obtained via anionic ring opening oligomerization (ROO).
• We examine the molecular structure of p-coumaric acid–oligo(3-hydroxybutyrate) conjugates by ESI-MSn.
• A novel controlled release and delivery system for application in cosmetology was developed.

The synthesis of new biodegradable delivery system of p-coumaric acid (p-CA) for prospective application in cosmetology is described. p-Coumaric acid conjugates with oligo(3-hydroxybutyrate) (p-CA-OHB) were obtained via anionic ring opening oligomerization (ROO) of β-butyrolactone initiated by p-coumaric acid potassium salt. Electrospray ionization mass spectrometry (ESI-MS) analyses in positive-ion mode, supported by 1H NMR results, were used for the structural characterization at the molecular level of the obtained products. The obtained results indicated that the main product constitutes the conjugate of p-coumaric acid covalently bonded with oligo(3-hydroxybutyrate) chains through a hydrolysable ester bond. Moreover, application of ESI-MS allowed to detect two minor series of ions which corresponded to 3-hydroxybutyrate oligomers terminated by crotonate, hydroxyl and carboxyl end groups, respectively. Additionally, ESI-MS/MS tandem mass spectrometry studies validated the structure of the individual macromolecules of the obtained bioconjugate as well as the side products.

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