Phenanthrene Derivatives, 3,5-Dimethoxyphenanthrene-2,7-diol and Batatasin-I, as Non-Polar Standard Marker Compounds for Dioscorea Rhizoma

Phenathrene derivatives, such as batatasins, are well-known constituents in Dioscorea Rhizoma. Although phenanthrenes have been reported as representative compounds in this plant, standard markers for quality control have been focused on the polar constituents (saponins and purine derivatives). Herein, simple, rapid and reliable HPLC method was developed to determine 3,5-dimethoxyphenanthrene-2,7-diol (DMP) and batatasin-I (BA-I) as non-polar standard maker compounds of Dioscorea Rhizoma. DMP and BA-I were analyzed under optimized HPLC conditions [column: Columbus $5{\mu}$ C18 100A ($30{\times}4.6mm$ i.d., $5{\mu}m$; mobile phase: $H_2O$ with 0.025% $CH_3COOH$ (v/v) for solvent A and $CH_3CN$ with 0.025% $CH_3COOH$ (v/v) for solvent B, gradient elution; flow rate: 2 mL/min; detection: 260 nm), and each experiment was finished within 13 min. Good linearity was achieved in the range from 0.5 to $10.0{\mu}g/mL$ for each compound, and intra- and inter-day precision were in the acceptable levels. The recovery test were performed with three different Dioscorea Rhizoma samples (D. opposita, D. batatas and D. japonica), and showed its accuracy values in the range of 97.2 - 102.8% for three different concentrations of DMP and BA-I. The content levels of DMP and BA-I were ranged under 0.0020%. These results demonstrated that amounts of DMP and BA-I are easily determined with conventional HPLC-UV-DAD method although the content levels were lower than those of saponins and allantoin in Dioscorea Rhizoma. This HPLC method could be used for quality control of various Dioscorea preparations.