Augmentation of ferulic acid-induced vasorelaxation with aging and its structure importance in thoracic aorta of spontaneously hypertensive rats

Aging deteriorates vascular functions such as vascular reactivity and stiffness. Thus far, various reports suggest that bioactive compounds can improve vascular functions. However, few age-related studies of natural bioactive compounds are available. The present study attempted to evaluate age-related vasorelaxation of bioactive cinnamic acids, caffeic acid, and ferulic acid using aged rat thoracic aorta. Vasorelaxation was evaluated in thoracic aorta from both 8, 18, and 40 weeks old Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) respectively. The result indicated that caffeic acid possessed the vasorelaxation regardless of aging in WKY and SHR. Moreover, the vasorelaxation of ferulic acid enhanced with aging in SHR. The vasorelaxation behavior was acted in an endothelium-independent manner. To access structure importance of enhanced vasorelaxation, analogues of ferulic acid were tested. In 40 weeks old SHR, 3,4-dimethoxycinnamic acid and coniferyl alcohol exhibited equivalent vasorelaxation activity with ferulic acid, providing the structural importance of methoxy-modified 3-position on the phenyl ring and 2-propenoic moiety. These results firstly demonstrated that enhanced vasorelaxation of ferulic acid with aging and 3,4-dimethoxycinnamic acid and coniferyl alcohol, along with ferulic acid, might exhibit the therapeutic potential of vasoactive power with aging.