Schisandra chinensis (SC), a member of the Magnoliaceae family, has been used to improve the vascular health for postmenopausal women in Korea. In order to provide some scientific rationales for such effectiveness, this study investigated the vascular effects of gomisin A (GA) from SC. In the endothelium (ED)-intact rings of rat thoracic aorta, GA (1 x 10 (-6) to 3 x 10 (-4) M) caused a concentration-dependent relaxation which was markedly attenuated not only by removal of ED but also by pretreatment with N(G)-nitro- L-arginine (10 (-4) M) or 1 H-[1,2,4]oxadiazol[4,3- a]quinoxalin-1-one (3 x 10 (-5) M). Direct measurement of nitrite, a metabolite of nitric oxide (NO), confirmed that NO production in isolated aorta was increased by GA. In the ED-denuded specimens, the relaxation by GA was not abolished but reduced significantly. The relaxation by GA in ED-denuded aortic rings were clearly inhibited by calyculin A (3 x 10 (-8) M), an inhibitor of MLC phosphatase. Furthermore, the phenylephrine-enhanced phosphorylation ratio of MLC was significantly attenuated by GA. Based on these results, it is suggested that GA induced vascular relaxation by partially activating ED-dependent NO pathway, and partially dephosphorylation of MLC.

In this study, the effects of dibenzocyclooctadiene on seed germination were investigated in pepper. Four C18 dibenzocyclooctadiene lignans -schisandrin (1143.7 mg), schisandrin C (317.3 mg), gomisin A (261.4 mg) and gomisin N (213.4 mg) -were isolated from hexane extracts of the fruits of Schisandra chinensis. The molecular structures of the four lignans were elucidated based on spectroscopic analyses including 1D NMR experiments, and by comparing their spectroscopic data with those of previous literatures. Seeds were immersed in 10 -5 M schisandrin, 10 -6 M schisandrin C, and 10 -7 M gomisin A and gomisin N for 1 hr and incubated at 25 o C in the dark for germination. Compared to untreated control, treatment with schisandrin C and gomisin A suppressed seed germination at 48 hrs after incubation, whereas treatment with gomisin N increased germination rate at 48 hrs after incubation. The results of the germination activity of the lignans from S. chinensis confirm their potential plant growth role, and the relative natural abundances of these metabolites suggest their potential use as natural plant growth regulators.