Spasmolytic Effects, Mode of Action, and Structure−Activity Relationships of Stilbenoids from Nidema boothii^,

Abstract

A CH(2)Cl(2)-MeOH (1:1) extract prepared from the whole plant of Nidema boothii inhibited spontaneous contractions (IC(50) = 6.26 +/- 2.5 microg/mL) of the guinea-pig ileum. Bioassay-guided fractionation of the active extract led to the isolation of the novel spiro compound 1, which was given the trivial name nidemone, and the new dihydrophenanthrene 3, characterized as 1,5,7-trimethoxy-9,10-dihydrophenanthrene-2,6-diol. In addition, the known stilbenoids aloifol II (2), 1,5,7-trimethoxyphenanthrene-2,6-diol (4), ephemeranthoquinone (5), gigantol (6), ephemeranthol B (7), 2,4-dimethoxyphenanthrene-3,7-diol (8), lusianthridin (9), and batatasin III (10) were obtained. The isolates were characterized structurally by spectroscopic data interpretation. Compounds 2-6, 9, and 10 induced notable concentration-dependent inhibition of the spontaneous contractions of the guinea-pig ileum with IC(50) values that ranged between 0.14 and 2.36 microM. Bibenzyl analogues 23-35 were synthesized and tested pharmacologically. The results indicated that for maximum spasmolytic activity the bibenzyls should have oxygenated substituents on both aromatic rings; on the other hand, methylation of free hydroxyl groups as well as the increment of oxygenated groups in relation to compounds 6 and 10 decreased the smooth muscle relaxant activity. It was also demonstrated that bibenzyls 6 and 10 might exert their spasmolytic action not only by a nitrergic mechanism but also by inhibiting CaM-mediated processes.

Synthesis of Phenanthrenes and Polycyclic Heteroarenes by Transition‐Metal Catalyzed Cycloisomerization Reactions

“…Moreover, many other closely related phenanthrenes have been isolated from various plant sources, many of which have not yet been assessed in detail for possible tubulin binding or cytotoxicity. [50] Pertinent examples are compound 44 derived from Alnus maximowiezii, [51] and phenanthrene 43 isolated from the orchid Bulbophyllum vaginatum [52] which have been included in the present study as simplified yet naturally occurring analogues of the lead compound 40.…”

Chemical constituents of Dendrobium cariniferum

“…The mass spectral fragmentation is consistent with two hydroxyls on a benzene ring and a hydroxyl group on another benzene ring. By comparison of the spectral data with those reported in literature, 3 was identified as 3,3′,5-trihydroxybibenzyl [11]. All the compounds were isolated from the plant for the first time.…”

Isolation of Stilbenoids and Lignans from <i>Dendrobium hongdie</i>

“…Some of the isolated compounds have been evaluated for biological properties and significant results were reported. Examples are the inhibition of ephemeranthoquinone on the spontaneous contraction of the guinea-pig ileum, spasmolytic, allelopathic and inhibitory activities of batatasin III on germination and radicle growth, and cytotoxicity of tristin against human stomach cancer SGC-7901 [6,[14][15][16][17][18][19].…”