Download - LC-MS and LC-MS-MS as a tool in standardizing extracts of medicinal plants - ChromSAAMS 2008
LC-MS and LC-MS/MS as a tool in standardizing extracts of medicinal
plants
N. Harding, G. Fouche, V.J. Maharaj, N. Moodley, D. Naidoo,
P.A.Steenkamp, and S. van Rooyen.
CSIR, Biosciences, P.O. Box 395, Pretoria, 0001, South Africa
© CSIR 2007 www.csir.co.za
Drug Discovery
Competency Area
Bioprospecting Discovery Chemistry Specialty groups
© CSIR 2007 www.csir.co.za
Information Identification
of active
components
Extract(s)
Biological
screening
Activity
NCE/mixture
Formulation
Preclinical
Workup
*
*
© CSIR 2007 www.csir.co.za
What do we mean by standardization?
• Standardize: to cause to conform to a standard.
• Why? - Establish a ‘baseline’ chemical profile.
- Establish variations between cultivation/harvesting sites.
- Stability studies.
- Final product specification – QC.
• What? - All compounds in the crude extract?
- Herbal mixture: how many components?
- Final formulation, actives, chemical ‘markers’
© CSIR 2007 www.csir.co.za
Consideration I
• Concentration of the sample. - Too high – overload column, contaminate system, distorted
spectra. - Too little – don’t see all the components. - Impossible to estimate the concentration of individual
compounds in an unknown sample.
© CSIR 2007 www.csir.co.za
A ‘simple’ extract …..
• Diethyl ether extract of a plant.
• Final formulation, diethyl ether not pharmaceutically acceptable, solubility problems, ether presents health and safety issues for technology/knowledge transfer.
• Ethanol used to extract plant material, pharmaceutically acceptable, safer.
• Chromatogram of ethanol extract is similar, ‘active’ present in approximately the same concentration.
• The challenge …….
- The ethanol extract has no activity!
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Consideration II
• Separation is important! - Co elution – combined spectra.
- Completive ionization.
- Choice of column chemistries
- Mobile phase considerations.
• LC-MS: - Sensitivity is due to selectivity and efficient ionization. - How do you set up for true unknowns?
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Consideration III
• Data processing and interpretation.
• It is easy to produce data, but how do you turn that data into useful information?
© CSIR 2007 www.csir.co.za
• By using product ion scan of 515m/z and information published by Michael Clifford in the Journal of Agricultural and Food Chemistry we were able to identify the isomers of Dicaffeoylquinic acids present in the sample.
(Clifford, M. N. Discriminating between the six Isomers of Dicaffeoylquinic Acid by LC-MS. J. Agric. Food Chem. 2005, 53,
3821-3832)