RÉSUMÉ
This study was aimed to analyze the content variations of chemical constituents produced in fresh Radix Rehmanniae (Xian-Di-Huang) after processing into Radix Rehmanniae Recens (Sheng-Di-Huang) and Radix Rehmanniae Preparata (Shu-Di-Huang). HPLC was used in the study of preparing Xian-Di-Huang into Sheng-Di-Huang, and the processing into Shu-Di-Huang. The contents of two newly produced chemical components, which were 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) and 5-hydryoxymethyl-furfural (5-HMF). The contents of both chemical components were determined in Sheng-Di-Huang and Shu-Di-Huang bought from the market. The Zorbax SB-C18 column (250 mm í 4.6 mm, 5 μm) was used. The mobile phase was methanol-wa-ter (5:95). The flow rate was 1.0 mL·min-1. The detection wavelength was set at 280 nm. The results showed that no DDMP or 5-HMF was detected in Xian-Di-Huang. However, after processing, DDMP and 5-HMF can be de-tected in both Sheng-Di-Huang and Shu-Di-Huang. The content in Shu-Di-Huang was higher than that in Sheng-Di-Huang. Both contents in Shu-Di-Huang were gradually increased along with processing time. The con-tent reached to the highest level after processing for 24 h and 32 h, respectively. And then, the content decreased. Both DDMP and 5-HMF were detected from three batches of Sheng-Di-Huang and ten batches of Shu-Di-Huang bought from the market. The content of 5-HMF was higher in Shu-Di-Huang than in Sheng-Di-Huang. There was no obvious difference in the content of DDMP between Sheng-Di-Huang and Shu-Di-Huang. It was concluded that DDMP and 5-HMF were produced in the processing Sheng-Di-Huang and Shu-Di-Huang. The contents were gradually increased along with the prolonging of processing time. There was obvious difference in the content of 5-HMF in Shu-Di-Huang and Sheng-Di-Huang.