Reagents and UHPLC−MS/MS analysis.
Seven STLs were detected in cultivated cardoon leaves: cynaropicrin,
cynaratriol, grosheimin, aguerin B, deacylcynaropicrin,
11,13-dihydro-deacylcynaropicrin and 11,13-dihydroxi-8-deoxygrosheimin
using santamarine as internal standard (IS). They were obtained
following Rial et al. (Rial et al. 2014) and Scavo et al. (Scavoet al. 2019e), while santamarin was synthesized according to Lu
and Fischer (Lu & Fischer 1996). Methanol, ethanol, dichloromethane and
formic acid were purchased from Fischer Chemicals (Geel, Belgium),
ammonium formate was obtained from Sigma-Aldrich (St. Louis, MO, USA)
and water for LC−MS/MS analysis was type I obtained from an Ultramatic
system from Wasserlab (Barbatáin, Spain). All the solvents were
UHPLC-grade. The UHPLC−MS/MS analysis was carried out in accordance to
Scavo et al. (Scavo et al. 2019f).