S. Estrada et al., Nitric oxide cGMP mediates the spasmolytic action of 3,4 '-dihydroxy-5,5 '-dimethoxybibenzyl from Scaphyglottis livida, PLANTA MED, 65(2), 1999, pp. 109-114
Five aromatic compounds, 3,4'-dihydroxy-5,5'-dimethoxybibenzyl (1), batatas
in 111 (2), coelonin (3), 3,7-dihydroxy2,4-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 concentrati
on-dependent inhibition of the spontaneous contractions of the rat ileum wi
th potencies comparable or higher to that of papaverine. The relaxation evo
ked by compounds 1 4 was blocked by L-NAME, an inhibitor of nitric oxide sy
nthase. 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 const
itute the signaling pathway in the spasmolytic action of compound 1.