A convenient TLC method for the quality control of turmeric

Turmeric, the dried rhizome of Curcuma longa Linn., is well documented for its medicinal properties and widely used for the treatment of several diseases. The biological effects of turmeric have been attributed to its constituent curcumin that has been studied for its anti-inflammatory, anti-angiogenic, antioxidant, wound healing and anticancer effects [1, 2]. For quality control, the content of curcuminoids in turmeric was to be determined by the spectrometric method at 420 nm according to Thai Herbal Pharmacopoeia (THP) Vol. 1 [3]. In this study, a simple and rapid thin layer chromatography (TLC) method for the determination of three curcuminoids, curcumin (CUR), desmethoxycurcumin (DES) and bisdesmethoxycurcumin (BIS) in turmeric was developed and validated. The method was performed on pre-coated silica gel TLC plates and the mobile phase consisting of chloroform-hexane-methanol (1:1:0.1, v/v/v). Quantification of each curcuminoid was carried out by image analysis technique using Photoshop software. The amount of curcuminoids in ten turmeric samples assayed by the proposed method was compared to those assayed by the official method in THP vol. 1. The statistical test showed no significant differences (p>0.05) between the methods, indicating that this TLC method is acceptable and convenient to assess the quality of turmeric as an alternative method for routine analysis.

Acknowledgements: The authors are thankful to Institute of Research and Development, Silpakorn University for providing funds for the research project.

References: 1. WHO Monographs on Selected Medicinal Plants Part 1 Vol. 1 (1999), World Health Organization, Geneva, Switzerland. 2. Radha, K. et al. (2006), Life Sciences, 78: 2081–2087. 3. Thai Herbal Pharmacopoeia Vol. 1 (1995), Prachachon Co., Ltd., Bangkok.