Discovery and validation of peptide biomarkers for discrimination of Dendrobium species by label-free proteomics and chemometrics.

The stems of Dendrobium officinale, a well-known and expensive food material and herbal medicine in Asia, has recently suffered adulterants and counterfeits by using lower-price confusing Dendrobium species such as D. devonianum or D. transparens in the herbal market. However, robust methods that could authenticate D. officinale from its confusing species effectively are still lacking, especially for the dried samples. This study committed to discover specific peptides biomarkers for the authentication of D. officinale from the other two Dendrobium species using label-free proteomics by nanoLC LTQ Orbitrap mass spectrometry. Multivariate statistical analysis was applied to visualize the difference between the three Dendrobium species. As a result, 29 peptides among a total of 343 measurable peptides were selected to be potential biomarkers for the classification of these Dendrobium species. The validation of the representative peptide biomarkers was carried out by the synthesized peptides and 3 peptide biomarkers were found significant for the authentication of D. officinale. Further analysis showed that peptide ALGLELDLSER may also be a biomarker for the discrimination of the D. officinale originated from different geographical regions.