RESUMEN
<p><b>OBJECTIVE</b>To study on effect of concentration of catalpol and 5-hydroxy methyl-2-furaldehyde (5-HMF) from Rehmanniae Radix at various processing.</p><p><b>METHOD</b>The Rehmanniae Radix was dried and prepared from the steaming process with 10% ethanol, 50% ethanol at 90 degrees C and 100 degrees C each other. And the changes of catalpol and 5-HMF was determinated. The extraction of 5-HMF and catalpol was sonicated in 30% methanol for 2 h. The analysis of 5-HMF and catalpol was conducted by HPLC with reversed-phase C-18 column and detected under UV 284 nm, 204 nm. Elution was carried out at 1.0 mL min(-1) with 3% acetonitrile.</p><p><b>RESULT</b>From this analysis, we found out that the content of catalpol was decreased with the number of processing times, and content of 5-HMF was increased with the number of processing times at various processing. The temperature and concentration of ethanol can effect on content of catalpol and 5-HMF at processing. The Cooked Rehmanniae Radix processed at 100 degrees C, 10% ethanol is best. And the content of 5-HMF processed for more than 7 times was accorded with standard of Korea phamcopoetia.</p><p><b>CONCLUSION</b>Analyze the effect of concentration of catalpol and 5-HMF from Rehmanniae Radix at various processing, and provide the foundation for further study.</p>