Profiles of phenolic acid derivatives from tuberous roots of yacon (Smallanthus sonchifolius) using UPLC-DAD-QToF/MS

The reported/proposed positive ion fragmentation of phenolic acid derivatives in yacon (Smallanthus sonchifolius) were summarized in the constructed LC-MS library for identification based on the literature. A total of fifteen phenolic acid derivatives (fourteen caffeoyl derivatives and one p-coumaroyl derivative) were separated and identified from the tuberous roots of yacon using UPLC-DAD-QToF/MS. Each caffeoyl derivative was conjugated with altraric acid, quinic acid, and octulosonic acid. The total content of each caffeoyl derivative was as follows: caffeoylaltraric acids (1,218.4 mg/100 g dry weight)> caffeoylquinic acids (331.5)> caffeoyloctulosonic acids (125.2). In particular, 2,3,5-or 2,4,5-tri-O-caffeoylaltraric acid (63% of the total phenolic acid derivatives) showed the highest contents followed by 5-O-caffeoylquinic acid (chlorogenic acid, 14%). Moreover, 2,3,5-or 2,4,5-tri-O-caffeoylaltraric acid methyl ester and 5-O-p-coumaroylquinic acid as new phenolic acid derivatives in yacon were identified putatively by the mass spectral data. This indicates that the individual phenolic acid derivatives in yacon might be determined easily using the constructed LC-MS library. Furthermore, it can provide valuable information for future studies on the health-promoting properties of yacon.