Isolation and characterization of Steroidal Alkaloids from Buxus macowanii using chromatographic and spectroscopic methods
Bibliographic record
Abstract
This thesis describes the isolation and characterization of four steroidal alkaloids from Buxus macowanii. Phytochemical investigation of Buxus macowanii resulted in the isolation of two novel steroidal alkaloids, Nb-demethyl-6-deoxy-16-acetoxy O2-natafuranamin (112), and 6-deoxy-16-acetoxy O10-natafuranamin (113) alongside two known steroidal alkaloids, cycloprotobuxine-D (114), and cycloprotobuxine-F (115). Compounds 114 and 115 have been isolated for the first time from B. macowanii. Structure of compounds 112-115 was elucidated with aid of UV, IR, mass, and 1D and 2D NMR spectroscopy. These compounds showed different level of anti-AChE activity. Among all the isolates, compound 112 was found to be significantly active against AChE with an IC50 value of 4.7 µM. The bioactivity of this new compound nearly comparable to those of huperzine (IC50 = 1.7 µM) and O2-natafuranamine (IC50 = 3.0 µM).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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 source (direct Gemma or distilled Codex), 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".