Identification of kukoamines as the novel markers for quality assessment of Lycii Cortex

•LC-MS-MS method was developed for simultaneous determination of 16 analytes in LyC.•Constituent profile shows that kukoamines are the major ingredients of LyC.•Kukoamines could be used to differentiate LyC from other cortex.•It is reasonable to use kukoamines as markers to assess the quality of LyC.

Lycii Cortex (LyC) serves not only as a medical herb but also as a functional food in daily life. In order to identify representative markers for assessment of its function-related quality, a high performance liquid chromatography coupled with electronic-spray ionization tandem mass spectrometric method was developed. This method allows for simultaneous determination of sixteen secondary constitutes, including spermine alkaloids, phenolic acids, coumarins and flavonoids in the LyC. The method was validated with linearity (R2 > 0.995), precision (with RSD < 4.56% for intra-day and < 4.92% for inter-day), reproducibility (with RSD < 7.71%) and accuracy (with recovery between 90% and 116% and RSD < 7.52%). Through this study, we found that kukoamines, with an average content of 0.8% of the dry mass, were the predominant and unique constituents in LyC. In contrast, phenolic acids, flavonoids and coumarins, which were previously regarded as the representative components for LyC, are minor constituents and less specific to LyC. In light of their predominant abundance, genus specificity and notable bioactivities, kukoamines are proposed as the new and representative markers for the quality control of LyC.