In traditional Chinese medicine, crude drugs are sometime processed and prepared for specific purposes. Rhubarb (Da-huang in Chinese; Daio in Japanese) has been processed by dipping or soaking it in huangjiu (Chinese fermented wine). However, the pharmacologic significance of this liquor processing has not been elucidated thoroughly. In this report, we describe how processing with ethanol altered the levels of the principal compounds in rhubarb: sennoside A, sennoside B, aloe-emodin, rhein, emodin, chrysophanol, physcion, lindleyin, isolindleyin, and total tannins. Liquor-dipping, dipping rhubarb in 16% ethanol for 30 seconds, did not affect the content of sennosides. Thus, the purgative effect of rhubarb is likely to be preserved. Liquor-soaking, soaking rhubarb in ethanol for 12 to 24 hours, the content of sennosides and tannins decreased and the content of anthraquinones increased. Liquor-soaking of rhubarb may increase its anti-bacterial and anti-inflammatory effects, thereby improving blood stasis. These results are in agreement with the descriptions in medicinal literatures published since the Jin and Yuan Dynasties.

Since ancient times in China, decocting times have been adjusted to improving objective medicinal effects. In medical texts, decocting times are dictated by the amount of water that is reduced. And in this report, we surveyed rhubarb (Chinese, Da-huang ; Japanese, Daio) formulation decocting times described in the earliest Shang-han-lun and Jin-gui-yao-lue texts, from the amount of water changed. We found that rhubarb decocting times could be divided into four 10-, 20-, 30- and 50-minute groups when rhubarb is decocted with other crude drugs, while when rhubarb is put in water after other crude drugs, decocting times could be divided into four 1-, 5-, 10- and 20-minute groups. Next, when we prepared rhubarb decoctions using unprocessed rhubarb and processed rhubarb, and compared change in the principal compounds eluted into those decoctions, we found that 80% or more of the principal compounds were eluted into a decoction when either unprocessed or processed rhubarb were decocted for 30 minutes. It was therefore clear that, in ancient times, rhubarb formulations were decocted for 10 to 30 minutes so that not all of the principle compounds would elute, or given 50 minutes to allow all the principle compounds to elute. Meanwhile, it was also clear that rhubarb was put in water1to 20 minutes before decocting finished, to adjust the amount of principle compound eluted.