Optimization of Flavonolignan Analysis in Milk Thistle Raw Materials and Finished Products using HPLC-UV
Bibliographic record
Abstract
Milk thistle (Silybum marianum (L.) Gaertn.), traditionally used for the treatment and prevention of liver disorders, has recently been shown to have anticancer and anti-inflammatory properties [1,2]. As a popular dietary supplement, milk thistle was identified as a high priority for establishing a validated analytical method [3]. On July 22nd 2009, the AOAC International convened an Expert Review Panel (ERP) to review analytical methods for determining flavonolignans in milk thistle powdered seed, powdered extract and finished products. The ERP recommended additional optimization studies be undertaken prior to executing a single laboratory validation on INA Method 115.000 [4]. Herein we report optimized conditions for defatting milk thistle seeds prior to extraction of flavonolignans using a sulfuric acid treatment [5] rather than by Soxhlet extraction with hexane [6]. The optimal extraction of flavonolignans from milk thistle seeds was pre-treatment with 1.5% v/v sulphuric acid for 30 minutes followed by sonication in methanol at 45°C for 30 minutes. Further optimization experiments focused on decreasing run time, improving peak resolution and adjusting the mobile phase to allow either ultraviolet or mass spectral detection. Separation of the flavonolignans silychristin, silydianin, silybin A, silybin B, isosilybin A, and isosilybin B was achieved in 46 minutes with a core-shell C18 column at a flow rate of 0.4 mL/minute using gradient elution with mobile phase A: 0.1% formic acid and B: 0.1:80:20 (% v/v/v) formic acid:methanol:water. This method allows for fast, routine analysis of milk thistle seeds, extracts and finished products and is recommended for further validation studies. Acknowledgments: Partial support for this research from the Advanced Foods and Materials Network (AFMNet) and the Growing Forward Program, a joint venture between the B.C. Ministry of Agriculture and Lands and Agriculture and Agri-Food Canada, is gratefully acknowledged. References: [1] Davis-Searles PR, et al. (2005) Cancer Res 65: 4448–4457. [2] Post-White J, et al. (2007) Integr Cancer Ther 6: 104–109. [3] Blumenthal M, et al. (2011) HerbalGram 90: 64–67. [4] Rathbone R. (2008) AOAC International Available at http://www.aoac.org/dietsupp6/Dietary-Supplement-web-site/Final_Report_August_28.pdf. Accessed December 2011. [5] Subramaniam S, et al. (2008) Bioresour Technol 99: 2501–2506. [6] NSF International (2004) Silymarins in Milk Thistle by HPLC INA Method 115.000. Available at http://www.nsf.org/business/ina/milkthistle.asp. Accessed December 2011.
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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) | 0.000 | 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".