Vulgarenol, a Sesquiterpene Isolated from Magnolia grandiflora, Induces Nitric Oxide Synthases II and III Overexpression in Guinea Pig Hearts

Vulgarenol, a sesquiterpene isolated from Magnolia grandiflora flower petals, decreased coronary vascular resistance in the Langendorff isolated and perfused heart model, when compared to the control group [(15.2 ¥ 107 ð 1.0 ¥ 107) dyn s cmÐ5 vs. (36.8 ¥ 107 ð 1.2 ¥ 107) dyn s cmÐ5]. Our data suggest that this coronary vasodilator effect probably involved inducible and endothelial nitric oxide synthase overexpression (6.8 and 4.2 times over control, respectively), which correlated with increases in nitric oxide release [(223 ð 9) pmol mLÐ1 vs. (61 ð 11) pmol mLÐ1] and in cyclic guanosine monophosphate production [(142 ð 8) pmol mgÐ1 of tissue vs. (44 ð 10) pmol mgÐ1 of tissue], as compared to control values. This effect was antagonized by 3 μm gadolinium(III) chloride, 100 μm N-nitro-l-arginine methyl ester, and 10 μm 1H-[1,2,4]oxadiazolo[4,2-a]quinoxalin-1-one. Hence, the vulgarenol-elicited coronary vasodilator effect could be mediated by the nitric oxide-soluble guanylyl cyclase pathway.