Does roasted coffee contain chlorogenic acid lactones or/and cinnamoylshikimate esters?

- Seven samples of commercial roasted Robusta coffee were analyzed.
- Chlorogenic acid lactones & hydroxycinnamoylshikimates were analyzed by LC-MSn.
- A series of C1-acylated chlorogenic acids are reported.
- Hydroxycinnamoylsikimate esters are reported for the first time from roasted coffee.

Coffee is one of the most popular and consumed beverages in the world with many positive health effects. In this study the chlorogenic acid lactones and cinnamoylshikimate esters, a subclass of phenolics, from seven commercial roasted Robusta coffee samples were detected and characterized by LC-MSn (n = 2-4). This is the first time when cinnamoylshikimate esters are reported in roasted coffee based on their tandem MS data. We used a previously developed LC-MSn method to distinguish between chlorogenic acid lactones and cinnamoylshikimate esters. Chlorogenic acid lactones and their isomeric shikimate esters have identical m/z values in their MS spectra but different tandem MS spectra and retention times. Structures of these chlorogenic acid lactones and shikimate esters were assigned on the basis of LC-MS3 patterns of fragmentation, relative hydrophobicity and fragmentation analogy to the synthetic standards of mono-acyl chlorogenic acid lactones and shikimate esters containing moieties of ferulic, caffeic, p-coumaric and dimethoxycinnamic acids. Furthermore, 7 unknown and 52 known mono and diacyl chlorogenic acids were identified and characterized to their regioisomeric level. The study is relevant for profiling chlorogenic acids and their dehydration derivatives, shikimates and lactones, in roasted coffee.