Simultaneous identification and quantitation of 11 flavonoid constituents in Kaempferia parviflora by gas chromatography.

Kaempferia parviflora (Krachaidum; KD) is a Thai herb, the rhizomes of which have been used in folk medicine and ritual ceremonies. The increasing use of KD has led to concerns regarding the variation of quality, potency and efficacy of KD products. A gas chromatographic method was developed and validated using 11 flavonoids that had been fully characterized as reference. Limits of detection ranged from a low of 0.1 ppm to a high of 1.0 ppm. The limits of quantitation were a low of 0.5 ppm (5-hydroxy-3,7-dimethoxyflavone) to a high of 3.0 ppm (5,7,4'-trimethoxyflavone and 5,7,3',4'-tetramethoxyflavone). Precision of intra- and inter-day analyses gave a RSD range of 3.02-8.25 and 2.84-12.37, respectively. The diversity of flavonoid content and their distribution profiles in KD samples from 12 different origins was investigated using the validated method. Total flavonoid content in these samples ranged from 23.86 to 60.98 mg/g. Two of the compounds, 5,7-dimethoxyflavone and 5,7,4'-trimethoxyflavone, emerged as major constituents. Samples contained as much as 21.68 and 9.88 mg/g, respectively. Two distinct patterns of the distribution of the flavonoids, as characterized by the ratio of these two compounds in the KD rhizome samples, were observed. This method is expected to be useful in the quantitative and qualitative analyses of the flavonoid content of KD samples and as a quality control assessment of KD raw materials and products.