Quantitative Analysis of Curcumin, Demethoxycurcumin and Bisdemethoxycurcumin in the Crude Curcuminoid Extract from Curcuma longa in Thailand by TLC-DensitometryWerayut Pothitirat and Wandee Gritsanapan*
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Curcuminoids, the principal natural yellow pigments comprising curcumin, demethoxycurcumin and bisdemethoxycurcumin, in Curcuma longa rhizome have been popularly used in drugs and cosmetics as potent antioxidants and coloring agents. This study, C. longa rhizomes were collected from 10 locations in the northern, northeastern, central and southern parts of Thailand. The powdered samples were continuously extracted using a soxhlet apparatus with hexane and 95% ethanol, respectively. Hexane was used to defat the sample. Curcuminoids, curcumin, demethoxycurcumin and bisdemethoxycurcumin, were isolated from the ethanol extract using column chromatography. Yields of crude curcuminoids in all samples were found in the range of 2.7-4.7% dry weight. Individual curcuminoid content was analyzed using a TLC-densitometry. The content of curcumin in all extracts was found in the range of 46.45 ± 3.21% to 67.31 ± 0.97% w/w while the contents of demethoxycurcumin and bisdemethoxycurcumin were found in the ranges of 11.47 ± 0.61% to 23.81 ± 0.28% w/w and 5.97 ± 0.41% to 13.88 ± 0.86% w/w, respectively. The highest average contents of curcumin (60.16 ± 3.23% w/w) and bisdemethoxycurcumin (12.84 ± 0.57% w/w) were found in the samples from the south while the highest average content of demethoxycurcumin (22.63 ± 1.33% w/w) was found in the samples from the north-east. In contrast, the lowest average contents of curcumin (53.65 ± 8.31% w/w) and demethoxycurcumin (16.23 ± 5.23% w/w) were found in the samples from the north, while the lowest content of bisdemethoxycurcumin (7.83 ± 0.28% w/w) was found in the samples from the central area. Total curcuminoid content in the crude curcuminoid extract was in the range of 67.13-96.25% w/w. This is the first report of each curcuminoid content in crude curcuminoid extract of C. longa from various locations of Thailand and will provide a useful guidance for further standardization of curcuminoid extracts used in pharmaceutical products and cosmetics.
Keyword:
bisdemethoxycurcumin, Curcuma longa, curcumin, curcuminoid extract, demethoxycurcumin, TLC-Densitometry
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