| In vitro: |
| Br J Pharmacol. 1971 Apr;41(4):683-90. | | Pyrrolizidine alkaloids: actions on muscarinic receptors in the guinea-pig ileum.[Pubmed: 5579465] |
METHODS AND RESULTS:
1. Eleven pyrrolizidine alkaloids have been tested on the isolated guinea-pig ileum preparation.2. Platyphylline, supinine, heleurine and cynaustraline were more potent in antagonizing responses to acetylcholine and carbachol than responses to histamine. Their anticholinergic activity appeared to involve a competitive mechanism.3. Lasiocarpine, monocrotaline, Spectabiline, sarracine, 7-angelylheliotridine, heliotrine and senecionine had similar antagonistic potencies against responses to both acetylcholine and histamine.
CONCLUSIONS:
4. The alkaloids had no appreciable activity as antagonists of acetylcholine in the isolated toad rectus abdominis preparation.5.
These results are discussed with respect to interactions of the alkaloids at receptor sites involved in anticholinergic activity at the muscarinic receptor. | | J Pharm Sci. 1968 Jul;57(7):1112-7. | | Tumor-inhibitory activity of pyrrolizidine alkaloids[Reference: WebLink] |
METHODS AND RESULTS:
Eighteen pyrrolizidine alkaloids and several derivatives have been examined for tumor-inhibitory properties. Of these, 10 compounds show significant activity against one or more test tumors. Heliotrine, lasiocarpine, monocrotaline, Spectabiline, and senecionine are highly active against the Walker 256 (intramuscular) system.
CONCLUSIONS:
The activity pattern is consistent with the tumor-inhibitory action being associated with the allylic ester function which imparts alkylating ability and is also responsible for hepatotoxicity. |
|
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