Abstract
Paeoniae Radix (the roots of Paeonia lactiflora Pallas) is a crude drug that is used in Asia and Europe to improve blood flow. We
studied its vasodilator effect and mechanisms of action in vitro. The extract from Paeoniae Radix (PRE) relaxed prostaglandin F2a-precontracted aortic
ring preparations of isolated rat aorta that contained endothelium. Relaxation by
PRE did not occur in specimens without endothelium, and was inhibited by pre-treatment
with 10-4M NG-nitro-1-arginine methyl ester.
Paeoniflorin and paeonol, the main activecomponents of Paeoniae Radix, lacked a vasodilator
effect. The effect of the component gallotannin was examined after treating PRE with
tannase, but the product lacked a vasodilator effect. Pentagalloylglucose, hexagalloylglucose,
heptagalloylglucose, and octagalloylglucose were extracted from PRE; they relaxed
aortic rings with endothelium, but failed to relax aortic rings without endothelium.
We conclude that PRE exhibits an endothelium-dependent vasodilator effect on isolated
rat aorta. The active component is gallotannin.
Key words
Paeoniae Radix -
Paeonia lactiflora Pallas - Paeoniaceae - gallotannin - galloylglucose - endothelium-dependent relaxing
factor - nitric oxide - rat aorta