DNA-based authentication of plant extracts

DNA-based methods to authenticate raw food materials have gained wide acceptance in quality control. An advantage of these methods is their possible use in the (whole?) production chain from raw material to the final customer. The concentration of plant secondary compounds by extraction processes leads to valuable intermediary products that are useful in food, flavor and pharmaceutical industry. An authentication of the extract by DNA sequence information could complement the chemical pool of methods. Three different extract types (spissum ethanol extract from coneflower (Echinacea sp.) and tincture and fluid extract from chamomile (Matricaria chamomilla)) were choosen to proof the possibility of DNA-based authentication of plant extracts. Since plant secondary compounds strongly interfere with subsequent PCR reactions, the minor amounts of intact plant cells observed in the extracts were purified by a repeated dilution/concentration/separation process before extracting the DNA from the plant cells. Internal transcribed spacer (ITS) was successfully amplified from all extracts. The sequence comparison to published sequences in Genbank revealed the unambiguous identification of the plant DNA in the ‘Echinacea’ extract as originating from the genus Echinacea sp. with the closest similarity to Echinacea purpurea. The sequences from the two chamomile extracts were compared to a reference sample. The DNA-fragment from the tincture was in complete accordance with the reference while in the fluid extract two fragments of different sizes were amplified with one exactly matching the reference, while the other one originated from a different species. DNA-based authentication of plant extracts is feasible and could reliably complement/substitute chemical analysis.