Lignans analytical methods

Muir, A.D., Flax lignans analytical methods and how they influence our understanding of biological activity, J. Assoc. Off. AnaL Chem. bit., 89, 1147-1157, 2006. 

There is at present little need for reviews on chemistry and synthesis of lignans and neolignans. An adequate chemical coverage up to mid-1976 (122) was subsequently complemented up to the end of 1983 (56, 164). Synthesis was covered in a very substantial paper published in 1982 (161). This does not mean, of course, that after the indicated dates science has lost interest in lignoids. Indeed, precisely the opposite has happened due to the powerful stimulus provided by the discovery of new and potentially exciting applications. Concomitantly, synthetic procedures became more varied (16) and analytical methods became more sophisticated. 

Harris, R.K., Greaves, J., Alexander, D., Wilson, T., and Haggerty, W.J., Development of stahility-indicating analytical methods for flaxseed lignans and their precursors, in Food Phytochemicals II. Teas, Spices, and Herbs, Osawa, C.-T., Huang, M.-T., and Rosen, R.T. (Eds), American Chemical Society, 547, 295-305, Washington DC, WA, 1994. 

Various extraction methods for phenolic compounds in plant material have been published (Ayres and Loike, 1990 Arts and Hollman, 1998 Andreasen et ah, 2000 Fernandez et al., 2000). In this case phenolic compounds were an important part of the plant material and all the published methods were optimised to remove those analytes from the matrix. Our interest was to find the solvents to modily the taste, but not to extract the phenolic compounds of interest. In each test the technical treatment of the sample was similar. Extraction was carried out at room temperature (approximately 23 °C) for 30 minutes in a horizontal shaker with 200 rpm. Samples were weighed into extraction vials and solvent was added. The vials were closed with caps to minimise the evaporation of the extraction solvent. After 30 minutes the samples were filtered to separate the solvent from the solid. Filter papers were placed on aluminium foil and, after the solvent evaporahon, were removed. Extracted samples were dried at 100°C for 30 minutes to evaporate all the solvent traces. The solvents tested were chloroform, ethanol, diethylether, butanol, ethylacetate, heptane, n-hexane and cyclohexane and they were tested with different solvent/solid ratios. Methanol (MeOH) and acetonitrile (ACN) were not considered because of the high solubility of catechins and lignans to MeOH and ACN. The extracted phloem samples were tasted in the same way as the heated ones. Detailed results from each extraction experiment are presented in Table 14.2. 

MAZUR w, FOTSis T, wAhAlA k, ojala s, salakka A, ADLERCREUTZ H (1996) Isotope dilution gas chromatographic - mass spectrometric method for the determination of isoflavonoids, coumesterol, and lignans in food samples, Analytical Biochemistry, 233, 169-80. 

T Nurmi, S Heinonen, W Mazur, T Deyama, S Nishibe, H Adlercreutz. Analytical, nutritional and clinical methods. Lignans in selected wines. Food Chem 83 303-309, 2003. 

Recently we developed and validated a nice reverse phase PHLC method to analyze the lignans in Schisandra fruits. Analytical HPLC analyses were performed on a Hewlett-Pachard 1100 modular system equipped with an autosampler, a quaternary pump system, a photodiode array detector and a HP Chemstation data system. A pre-packed 250 x 4.6 mm (5 pM particle size) Luna Cl8 (2) column (Phenomenex, Torrance, CA) were selected for HPLC analysis. The absorption spectra were recorded from 200 to 400 nm for all peaks quantification was carried out at a single wavelength of255 nm. 

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