Dopaminergic Activity of Some Ergot Alkaloid Derivatives: Relationship to Their Chemical Structure
Bibliographic record
Abstract
Several ergot alkaloid derivatives have been tested for their ability to inhibit receptor binding of [3H]spiperone (D2 dopamine receptors) and [3H]dopamine (D3 dopamine receptors) in the bovine caudate nucleus. Dopaminergic activity was correlated to their chemical structure. The potencies of ergot alkaloids for displacing [3H]spiperone binding can be ranked in the following order: lisuride greater than ergosine greater than bromodihydroergosine greater than bromoergosine approximately dihydroergosine approximately ergosinine approximately dihydroergocryptine greater than bromoergocryptine greater than CH-29 717 greater than saccharinoergosinine = saccharinoergosine greater than dihydroergosinine. The potencies of these compounds for displacing [3H]dopamine binding can be ranked in the following order: lisuride greater than ergosinine approximately ergosine greater than dihydroergosine greater than bromodihydroergosine approximately CH-29 717 approximately bromoergocryptine approximately bromoergosine approximately dihydroergocryptine greater than saccharinoergosine, saccharinoergosinine, dihydroergosinine. Displacement of both radioligands was unaffected by GTP. Binding characteristics of ergot alkaloids examined revealed antagonist-like properties of binding to D2 and agonist-like properties of binding to D3 receptors. Introduction of bromine into position 2, selective hydrogenation of 9,10-dihydroderivatives, or isomerization in position 8 of the ergot alkaloid molecule did not drastically change binding parameters of these compounds. However, an alpha-configuration in position 8 combined with hydrogenation of the delta-9,10-double bond of dihydroergosinine, significantly decreased its affinity to both D2 and D3 receptors in comparison with dihydroergosine or ergosinine, suggesting stereoselectivity of dopamine receptors towards the pair dihydroergosine/dihydroergosinine.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".