LAUSR

Magnolol is a biologically active compound isolated from Magnolia officinalis, which has been used as a traditional medicine for the treatment of stroke and myocardial infarction, and exerts vasodilator and anti-platelet activity [1] . We undertook a study to determine whether leaf and bark extracts from a different member of the Magnolia family (Magnolia poasana; MP) not used in traditional medicine, possess similar biological activity. In rat isolated mesenteric arteries pre-contracted with U46619, magnolol induced a concentration-dependent relaxation (Emax 98.8 ± 3.4%; EC50 4.4x10−5 M) that was resistant to L-NAME (10−3 M) demonstrating a mechanism independent of nitric oxide. MP bark extract (0.1–50 μg ml−1) induced a 66.9 ± 11.9% relaxation, which was similarly L-NAME resistant, while the leaf extract induced a smaller relaxation (38.9 ± 3.9%; 50 μg ml−1) that was reduced in the presence of L-NAME (27.8 ± 1.7%; P