Degradation during extraction

All extract preparation and analysis methods have biases and potential weaknesses. For example, most of the methods described above recover polar, water-soluble compounds poorly if at all, very volatile compounds may be obscured by solvent peaks during analysis, or compounds may degrade during extraction or analysis (e.g., [25]). 

Natural Product Degradation During Extraction and/or Chromatography... 

Cichoric acid is believed to contribute to the immunostimulatory activity, but the compound tends to decompose through enzymatic degradation during extractions (Bauer, 1997) thus, the variability in cichoric acid levels found by many researchers may be due to the extraction methodology and not to the plant species or origin. Bauer (1999b) evaluated the cichoric acid content of six commercially available expressed juice preparations of E. purpurea. The thermally treated preparations had higher cichoric acid than ethanol-preserved preparations. The inactivation of polyphenol oxidase by heat may account for the difference found between heated and nonheated preparations. 

A more detailed discussion on this topic can be found in Section 7.5.5(e) on the use of isotopically labelled species for the determination of artefact formation or species degradation during extraction and derivatisation reactions. 

As pheophytin a and pheophytin b are the major degradation derivatives formed during extraction, food processing, and storage, some authors reconunend converting chlorophylls into the more stable pheophytins by treatment with HCl, ion exchange resin, or oxalic acid to estimate the chlorophyll contents. ... 

Specifically for triazines in water, multi-residue methods incorporating SPE and LC/MS/MS will soon be available that are capable of measuring numerous parent compounds and all their relevant degradates (including the hydroxytriazines) in one analysis. Continued increases in liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) sensitivity will lead to methods requiring no aqueous sample preparation at all, and portions of water samples will be injected directly into the LC column. The use of SPE and GC or LC coupled with MS and MS/MS systems will also be applied routinely to the analysis of more complex sample matrices such as soil and crop and animal tissues. However, the analyte(s) must first be removed from the sample matrix, and additional research is needed to develop more efficient extraction procedures. Increased selectivity during extraction also simplifies the sample purification requirements prior to injection. Certainly, miniaturization of all aspects of the analysis (sample extraction, purification, and instrumentation) will continue, and some of this may involve SEE, subcritical and microwave extraction, sonication, others or even combinations of these techniques for the initial isolation of the analyte(s) from the bulk of the sample matrix. 

In the past, dissociation of the nucleoprotein complex has been brought about by salt solutions or by heat denaturation,129 but, more recently, decomposition has been effected by hydrolysis with trypsin,126 or by the use of dodecyl sodium sulfate130 or strontium nitrate.131 Some virus nucleoproteins are decomposed by ethyl alcohol.132 This effect may be similar to that of alcohol on the ribonucleoproteins of mammalian tissues. If minced liver is denatured with alcohol, and the dried tissue powder is extracted with 10% sodium chloride, the ribonucleoproteins are decomposed to give a soluble sodium ribonucleate while the deoxyribonucleoproteins are unaffected.133 On the other hand, extraction with 10 % sodium chloride is not satisfactory unless the proteins have first been denatured with alcohol. Denaturation also serves to inactivate enzymes of the tissues which might otherwise bring about degradation of the nucleic acid during extraction. 

Meadowfoam seeds differ from the seed meal in that seeds, even after years of storage, contain active myrosinase whereas the meal does not. In order to prevent myrosinase-mediated degradation of glucohmnanthin during extraction, one could inactivate myrosinase by applying heat or by choosing a solvent in which myrosinase does not exhibit activity. We have found that heating seeds at temperatures... 

The main problem in the vitamin E analysis is that it is easily oxidized, thereby an antioxidant, such as butyl hydroxy toluene (BHT) or ascorbic acid, is added to prevent degradation during the extraction step. The traditional method for extraction of tocopherols and tocotrienols in foods is solvent extraction (like soxhlet) and saponification with KOH [457,458]. Some authors have recently proved that saponification is not necessary [459-462], nevertheless, it has been widely applied until the present day. 

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