title: Stereochemical considerations in relation to the pharmacological activity of Pterotaberna alkaloids.
abstract: Five 2-acylindole alkaloids, isolated from the leaves of Pterotaberna inconspicua, were pharmacologically investigated. The major alkaloids methuenine and 16-epimethuenine showed some interesting pharmacological features, whereas the minor alkaloids including 6-oxomethuenine and methuenine N-oxide were almost devoid of these pharmacological properties. Methuenine, being the most potent, was characterized as a non competitive antagonist against acetylcholine (pD'2=5.10 +/- 0.11) and histamine (pD'2 = 5.13 +/- 0.14) in guinea-pig ileum. Its potency was comparable to that of papaverine. 16-Epimethuenine behaved as a weak antihistaminic (pA2 = 6.55 +/- 0.08). The stereochemistry of both components is discussed in relation to their pharmacological activity.
mesh_terms: D000470:Alkaloids / Q000032:analysis / Q000494:pharmacology*; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D015023:Democratic Republic of the Congo; D015232:Dinoprostone; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005260:Female; D006168:Guinea Pigs; D006633:Histamine Antagonists; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D008968:Molecular Conformation; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D010276:Parasympatholytics; D010946:Plants, Medicinal / Q000032:analysis*; D011458:Prostaglandins E / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D006633:Histamine Antagonists; D010276:Parasympatholytics; D011458:Prostaglandins E; D015232:Dinoprostone