The effect of Cu2+ on the accumulation of daidzein, genistein and coumestrol in the tuberous roots of White Kwao Krua [Pueraria candollei Grah. var. mirifica (Airy Shaw et Suvatabandhu) Niyomdham]

The White Kwao Krua [Pueraria candollei Grah. var. mirifica (Airy Shaw et Suvatabandhu) Niyomdham] is a famous medicinal plant of Thailand. Its tuberous roots accumulate estrogen like substances such as daidzein, genistein and coumestrol. The purpose of this study was to investigate the form and concentration of Cu²⁺ that can maximise daidzein, genistein and coumestrol in the tuberous roots of the White Kwao Krua. Two experiments were conducted on 1 and 3 year old plants of White Kwao Krua during 2001–2004at Suranaree University of Technology. Experiment 1 was a 3³ factorial in RCBD with 4 replications. The forms of Cu²⁺ compounds used were CuCl_2, CuSO ₄ and Cu-EDTA. The concentrations of Cu²⁺ were set at 0, 100, 300 and 500 ppm. The extraction and the analysis of daidzein and genistein were done according to the method of Murphy [1] and Frank et al. [2] by a HPLC technique. Experiment 2 was RCBD with 4 treatments and 4 replications. The treatment were CuCl₂, MnCl ₂ and FeCl₂ at 1,000 ppm each, and distilled water was used as control. The amount of coumestrol was examined using the method of Khanna et al. [3] by TLC technique. The Cu ²⁺ at 300 ppm showed the highest amount of daidzein (44.69 ppm) and genistein (28.45 ppm). All treatments with Cu²⁺ compounds gave more daidzein and genistein than the control. CuCl₂ at 1,000 ppm resulted in the highest amount of coumestrol. CuCl₂, MnCl₂ and FeCl₂ at 1,000 ppm can stimulate coumestrol accumulation.

Acknowledgements: Suranaree University of Technology and the Thailand Research Fund (TRF).

References: [1] Murphy, P. A. (1981) J. Chromatogr. 211: 166–169. [2] Frank et al., (1994) J. Agri. Food Chem. 42: 1905–1913. [3] Khanna et al., (1999) Transactions of the Illinois State Academic of Science. 92: 167–179.