Inhibition of Cyclic Adenosine Monophosphate-Specific Phosphodiesterase by Various Food Plant-Derived Phytotherapeutic Agents

Phosphodiesterases (PDEs) play a major role in the regulation of cyclic adenosine monophosphate (cAMP)- and cyclic guanosine monophosphate (cGMP)-mediated pathways. Their inhibitors exhibit anti-inflammatory, vasodilatory and antithrombotic effects. Therefore, consumption of foods with PDE-inhibiting potential may possess beneficial influence on the risk of cardiovascular diseases. Four plant extracts (, , , ) with promising ingredient profiles and physiological effects were tested for their ability to inhibit cAMP-specific PDE in vitro in a radioactive assay. Strawberry tree fruit () and tea () extracts did not inhibit PDE markedly. Alternatively, artichoke () extract had a significant inhibitory influence on PDE activity (IC = 0.9 ± 0.1 mg/mL) as well as its flavone luteolin (IC = 41 ± 10 μM) and 3,4-dicaffeoylquinic acid (IC > 1.0 mM). Additionally, the ginger () extract and one of its constituents, [6]-gingerol, significantly inhibited PDE (IC = 1.7 ± 0.2 mg/mL and IC > 1.7 mM, respectively). Crude fractionation of ginger extract showed that substances responsible for PDE inhibition were in the lipoid fraction (IC = 455 ± 19 μg/mL). A PDE-inhibitory effect was shown for artichoke and ginger extract. Whether PDE inhibition in vivo can be achieved through ingestion of artichoke or ginger extracts leading to physiological effects concerning cardiovascular health should be addressed in future research.