For the identification of bioactive phytocompounds

For the identification of bioactive phytocompounds by HRGC/MS or HPLC/MS,

the following conditions are useful when standards are available: a suspect peak

has to show a retention time similar to the average retention time of the pure stan-

dard or control sample and mass spectra for the suspect peaks have to show rela-

tive abundance ±10% (arithmetic difference) of the relative abundance of the stan-

dard analyzed that day. With HPLC/MS, applying the right separation, with the

right ionization interface and mass analyzer, significant information can be ob-

tained with regards to the target compounds. However, for the quantification of bi-

oactive phytocompounds in plant materials, the system precision will be higher

compared to that obtained using HPLC with ultraviolet detection. For on-line

HPLC/MS, the internal diameter of the column selected will be an important con-

sideration.

Another important chromatography technique is bioautography (Fig. 1.3). Bio-

autography is often used as an option to identify chemical groups of bioactive phy-

tocompounds or even a single bioactive phytocompound when padrons are avail-

able. The complex chemical composition of plant extracts is generally a limiting

obstacle to the isolation of antimicrobial compounds. Nevertheless, the use of bio-

autography agar overlay bioassays allows the detection of active components in a

crude plant extract. This method permits the localization of antimicrobial active

components that have been separated by TLC [33]. Precipitation with ethanol of

plant aqueous extracts allows the separation of polymers, such as polysaccharides

and proteins, from micrometabolites [34, 27]. By this technique, the solvation

between molecules is changed, and in the same way, the interaction between mole-

cules. Polymers (macromolecules) will be found in the water-soluble precipitate

and micrometabolites in the supernatant. The precipitation of macromolecules

can also be achieved by ammonium sulfate and acetone. The association of bioau-

tography and ethanol precipitation techniques allows the detection of otherwise

nondetectable bioactive phytocompounds

An extremely important aspect of chromatography techniques is to identify non-

natural molecules, such as paracetamol, that may be present in or added to health

supplements and commercially available herbal preparations.