Effects of a new 12-lipoxygenase inhibitor, daphnodorin A, on angiotensin II-induced vascular contraction in hamster

We studied whether lipoxygenase inhibition suppressed angiotensin Ii-induced vascular contraction. In the present study, we used a new 12-lipoxygenase inhibitor, daphnodorin A, and an analogue of daphnodorin A, daphnodorin B, which has no inhibitory effects on 12-lipoxygenase. Daphnodorin A at 30 mu M and 100 mu M significantly suppressed the contractile responses induced by angiotensin II (3 x 10(-8) M) in isolated hamster aorta, while daphnodorin B up to 100 mu M did not affect the responses. These results suggest that daphnodorin A, but not daphnodorin B, may suppress angiotensin II-induced vascular contractile responses through the inhibition of 12-lipoxygenase.