"Artichoke (Cynara scolymus) is known to contain flavones, mainly apigenin and luteolin glycosides [44,45,46], which have been reported to act as PDE inhibitors [12,13,14]. However, in this study no effect was observed when luteolin glycosides were tested. Furthermore, luteolin, which was demonstrated to be a strong PDE inhibitor in accordance with the literature, could not be found in the PDE-inhibiting extract."
"The supposed ALE constituents 1,3-dicaffeoylquinic acid and 1,5-dicaffeoylquinic acid were not commercially available, so an isomer, 3,4-dicaffeoylquinic acid, was used for the PDE inhibition experiments. As 3,4-dicaffeoylquinic acid concentrations increased to 500 μg/mL (~ 1mM), PDE activity decreased almost 50% (see Figure 4d)."
Inhibition of Cyclic Adenosine Monophosphate-Specific Phosphodiesterase by Various Food Plant-Derived Phytotherapeutic Agents
"The supposed ALE constituents 1,3-dicaffeoylquinic acid and 1,5-dicaffeoylquinic acid were not commercially available, so an isomer, 3,4-dicaffeoylquinic acid, was used for the PDE inhibition experiments. As 3,4-dicaffeoylquinic acid concentrations increased to 500 μg/mL (~ 1mM), PDE activity decreased almost 50% (see Figure 4d)."
Inhibition of Cyclic Adenosine Monophosphate-Specific Phosphodiesterase by Various Food Plant-Derived Phytotherapeutic Agents