Evaluation of rapid molecular diagnostics for differentiating medicinal Kaempferia species from its adulterants

Accurate detection of unique herbs is crucial for herbal medicine preparation. Zingiberaceae species, which are important in Ayurvedic medicine of India, are often misidentified in Northeast (NE) Indian herbal markets. Kaempferia galanga (Zingiberaceae) is one of the major components of popular Ayurvedic drugs used for rheumatic diseases (i.e., "Gandha Thailam" and "Rasnairandadi Kashayam"), contusions, fractures, and sprains. In NE India, herbal healers often misidentify plants from the Marantaceae family (e.g., Calathea bachemiana and Maranta leuconeura) as Kaempferia, which leads to adulteration of the medicinal herb. This misidentification of herbs occurs in NE India because Zingiberaceae plant barcoding information is inadequate. As a consequence, herbal medicine is not only therapeutically less effective but may also cause adverse reactions that range from mild to life-threatening. In this study, we used eight barcoding loci to develop "fingerprints" for four Kaempferia species and two species frequently mistaken for Kaempferia. The PCR and sequencing success of the loci matK, rbcL and trnH-psbA were found to be 100%; the combination of matK, rbcL, and trnH-psbA proved to be the ideal locus for discriminating the Kaempferia species from their adulterants because the combined loci showed greater variability than individual loci. This reliable tool was therefore developed in the current study for accurate identification of Kaempferia plants which can effectively resolve identification issues for herbal healers.