Development of a DNA microarray for authentication of ginseng drugs based on 18S rRNA gene sequence

Ginseng drugs, derived from underground parts of Panax species (Araliaceae), are the most important group of herbal medicines in the Orient. Previously, the nucleotide sequences of the nuclear 18S rRNA gene of 13 Panax taxa were determined, as were the specific polymorphic nucleotides for identification of each species. On the basis of the nucleotide difference, a DNA microarray (PNX array) was developed for the identification of various Panax plants and drugs. Thirty-five kinds of specific oligonucleotide were designed and synthesized as probes spotting on a decorated glass slide, which included 33 probes corresponding to the species-specific nucleotide substitutions and 2 probes as positive and negative controls. The species-specific probes were of 23-26 bp in length, in which the substitution nucleotide was located at the central part. Triplicate probes were spotted to warrant accuracy by correcting variation of fluorescent intensity. Partial 18S rRNA gene sequences amplified from Panax plants and drugs as well as their derived health foods were fluorescently labeled as targets to hybridize to the PNX array. After hybridization under optimal condition, specific fluorescent patterns were detected for each Panax species, and the analyzed results could be indicated as barcode patterns for quick distinction. The developed PNX array provided an objective and reliable method for the authentication of Panax plants and drugs as well as their derived health foods.