Nitric oxide/cGMP mediates the spasmolytic action of 3,4'-dihydroxy-5,5'-dimethoxybibenzyl from Scaphyglottis livida.
Five aromatic compounds, 3,4'-dihydroxy-5,5'-dimethoxybibenzyl (1), batatasin III (2), coelonin (3), 3,7-dihydroxy-2,4-dimethoxyphenanthrene (4), and 3,7-dihydroxy-2,4,8-trimethoxyphenanthrene (5) were isolated from the orchid Scaphyglottis livida (Lindley) Schltr. Compounds 1-5 induced a concentration-dependent inhibition of the spontaneous contractions of the rat ileum with potencies comparable or higher to that of papaverine. The relaxation evoked by compounds 1-4 was blocked by L-NAME, an inhibitor of nitric oxide synthase. It was also demonstrated that 1 increased cyclic GMP content in rat ileum rings. Compound 1-induced elevation of cGMP was inhibited by L-NAME and ODQ, inhibitors of nitric oxide synthase and soluble guanylyl cyclase, respectively. These results indicate that nitric oxide/cGMP formation constitute the signaling pathway in the spasmolytic action of compound 1.
Estrada
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S
Departamento de Farmacia, Facultad de Química, Universidad Nacional Autónoma de México, México.
Rojas
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A
Mathison
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Y
Israel
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A
Mata
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R
D000818:Animals; D001632:Bibenzyls / Q000302:isolation & purification / Q000494:pharmacology*; D006152:Cyclic GMP / Q000502:physiology*; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D010276:Parasympatholytics / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar
C118572:3,4'-dihydroxy-5,5'-dimethoxybibenzyl; D001632:Bibenzyls; D010276:Parasympatholytics; D009569:Nitric Oxide; D006152:Cyclic GMP