Effect of the uncharged imidazolium moiety in adenine on endothelium-independent relaxation in the contracted thoracic aorta of Sprague-Dawley rats.

Adenine had a concentration-dependent relaxation action on the phenylephrine-contracted aorta ring, with an EC(50) value of 0.40±0.12 mM.

Identification of a new natural vasorelaxatant compound, (+)-osbeckic acid, from rutin-free tartary buckwheat extract.

The candidates responsible for vasorelaxation action of rutin-free tartary buckwheat extract (TBSP) were examined in this study. As a result of reversed-phase high-performance liquid chromatography (HPLC) separations, five prominent peaks in the acidic fraction of TBSP were obtained at 260 nm. Among the five collected peaks, we successfully identified four compounds by nuclear magnetic resonance (NMR) and mass spectrometry (MS) measurements: (+)-osbeckic acid as a dimer ([M - H](-) m/z: 371.