Using 6-gingerol content and gene mapping to identify two types of Gingers used in Thai traditional medicine

Two species of ginger are used in Thai traditional medicine. Zingiber officinale Roscoe are commonly known as Khing or Khing Haeng which is widely used as food, carminative, stimulant and mixing in polyherbs remedies for balancing patient conditions. Another ginger is Zingiber ligulatum Roxb. [1], sometimes called Khing Klang or Khing Haeng which is only used as carmiative. The later ginger has less punget smell but often misunderstood and misused as Khing Haeng. Fresh rhizomes of gingers from 12 sources in 4 parts of Thailand were collected and studied for microscopic characters and 6-gingerol content. Also, the fresh leaves were studied for DNA profiles using amplified fragment length polymorphism (AFLP) methodology [2]. HPLC analyes revealed that 6-gingerol was found only in Z. officinale, not in Z. ligulatum. In addition, the DNA mapping was different in the two ginger species investigated, whereas the microscopic examination of dried rhizomes showed no differences. These results lead to the question whether commercial dried gingers from various sources were Z. officinale or not. Dried ginger rhizomes were purchased from 14 sources, represented 4 parts of Thailand, and was studied for standardization according to Thai Herbal Pharmacopoeia. The 6-gingerol was found in 12 samples in range of 0.72–8.24% w/w. The other 2 gingers were 6-gingerol-free were recollected as fresh specimens for growing, and then confirmed by AFLP as Z. ligulatum.

Acknowledgements: Thammasart University Research Fund for financial support.

References: 1. Hooker JD (1894) Flora of British India vol.1: 245.

2. Thai Herbal Pharmacopoeia (2000) vol. 2.

3. Vos P. et al (1995). Nucleic Acids Research 23: 4407–4414.

4. Yildirim F, Akkaya MS (2006). Genetic Resources and Crop Evolution 55: 1033–1042.