• Journal of Life Science
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• v.10 no.6
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• pp.584-590
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• 2000

Natural products are one of the useful source of cardiovascular drugs, in particular, when they have antioxidant activity. Gagaminine, an alkaloid isolated from the roots of Cynanchum wilfordi Hemsley, has been reported to potently inhibit the aldehyde oxidase activity ({TEX}$IC_{50}${/TEX}=0.8$\mu$M) and reduce lipid peroxidation. However, the effect of gagaminine on vascular smooth muscle has not yet been investigated. In the present study, we examined whether gagaminine relaxes vascular smooth muscle by isometric tension study. In order to observe its relaxation effect on the arteries, conductivel vessel (rat thoracic aorta) and resistance vessel (pig coronary artery) were purposely used. Results indicated that gagaminine relaxed in a concentration-dependent manner $\alpha$-adrenoceptor agonist, phenylephrine (PE)-induced contraction of rat aorta. Pretreatment with gagaminine inhibited PE-induced contraction, noncompetitively. {TEX}$Ca^{2+}${/TEX}-induced contraction was significantly diminished by gagaminine. In pig coronary artery, gagaminine relaxed thromboxane receptor (U 46619)-mediated contraction in dose-dependent manner. Pretreatment with gagaminine also reduced the maximum contraction induced by KCl. These observations strongly suggest that agagminnine relaxes vascular smooth muscle, irrespective of both resistance and conductive artery. We demonstrate that gagaminine, a potent natural antioxidant, has a significant vasodilatory effect and its action mechanism van be ascribed at least in part to {TEX}$Ca^{2+}${/TEX} antagonistic action as evidenced by inhibition {TEX}$Ca^{2+}${/TEX}-induced contraction (rat aorta) and KCl-induced contraction (porcine artery). Furthermore, neither $\alpha$ -adrenoceptor nor thromboxane receptor seems responsible for the relaxation of gagaminine.

• Archives of Pharmacal Research
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• v.21 no.3
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• pp.273-277
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• 1998

In order to determine the structure-activity relationships for antioxidative effects of gagaminine, a steroidal alkaloid isolated from the roots of Cynanchum wilfordi (Asclepiadaceae), two derivatives identified as sarcostin and penupogenin were prepared from gagaminine by hydrolysis and reduction. These compounds were evaluated for the inhibitory effects on the aidehyde oxidase activity and on lipid perbxidation in vitro. Furthermore, their effects were compared with those of gagaminine and the related compounds, cinnamic acid and nicotinic acid. The results of this study prove that the cinnamoyl group in the structure of gagaminine is critical in inhibition of the aldehyde oxidase activity while the nicotinoyl group may be necessary for anti-lipid peroxidation of the compound.

• YAKHAK HOEJI
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• v.44 no.3
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• pp.257-262
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• 2000

The roots of Cynanhum caudatum (Asclepiadaceae) have been used in folk medicine in Japan and China for the prevention and treatment of various geriatric diseases and also as a cardiotonic agent. Constituents of this plant have mainly been examined for glycosides: besides two steroidal alkaloids, gagaminine and gagamine which was firstly isolated by us, more than 35 polyoxypregnane glycosides and aglycones have also been identified. Gagaminine inhibits potently the hepatic aldehyde oxidase activity and lipid peroxidation in vitro. The present work deals with the comparison of antioxidative activities of gagamine, a new pregnane alkaloid, three isolated polyoxypregnanes containing a keto group at C-20 with those of gagaminine, a potent antioxidant, in order to explain the structure-activity relationships. The results of this study further prove that the cinnamoyl group of gagaminine is very important for the inhibition on the aldehyde oxidase activity while the nicotinoyl group is necessary for anti-lipid peroxidation. Besides that, the keto compounds having no ester group at C-12 were found to be more active than the others except gagaminine.

• Korean Journal of Pharmacognosy
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• v.28 no.4
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• pp.247-251
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• 1997

The effects of the extract of the root of Cynanchum wilfordi (Asclepiadaceae), the alkaloid fraction, and the isolated main constituent (gagaminine) on 5-lipoxygenase(5-LOEC 1.13.11.34) in bovine PMNL have been studied. The effect of the crude extracts of wildand cultivated plant was also compared each other. Furthermore, the inhibitory effect of gagaminine on 5-Lo was compared with those of the standard drugs. Gagaminine inhibited 5-Lo activity with an $IC_{50}$ value of $26\;{\mu}M$, this result indicates that gagaminine may be useful for in vivo experiments as 5-LO inhibitor.