Thin-layer chromatography-densitometry analysis of dimethoxyphenylbutadiene content in Zingiber cassumunar rhizomes.

Zingiber cassumunar (Zingiberaceae) has been widely used as a traditional medicine in southeast Asia, especially Thailand, for treatment of asthma, inflammation, and joint pain. (E)-4-(3,4-dimethoxyphenyl)butadiene, or DMPBD, a major component in the rhizome, has been reported to be an active anti-inflammatory agent. This research developed a TLC-densitometry method for the simultaneous quantification of DMPBD in the rhizome extracts of four varieties of Z. cassumunar. DMPBD (dimethoxyphenylbutadiene) was found in the range of 0.90 +/- 0.01 to 1.61 +/- 0.05% (w/w). [corrected] The method was validated for linearity, precision, accuracy, robustness, LOD, and LOQ. The linearity was indicated by a good regression coefficient 0.9940 and covered the range of 130 to 703 ng/band. Intraday and interday precision (RSD) were less than 2%. Accuracy of the method was evaluated by a recovery study conducted at three different levels; the average recovery was 103.1%. The LOD and LOQ were 10 and 40 ng, respectively. The proposed TLC-densitometry method was simple, precise, specific, sensitive, and inexpensive. This method can be used for routine QC of raw materials of Z. cassumunar rhizomes, extracts, and its products, especially Prasaplai, a Thai traditional medicine for relieving dysmenorrhea.