Proper pharmaceutical processing may reduce toxicity or side effects, potentiate the beneficial effects, change the pharmacological properties, preserve active constituents, facilitate administration, improve flavor or correct unpleasant taste and increase purity of Chinese materia medica[1–4]. In China, the processing methods for Radix Polygoni Multiflori have been practiced since the Tang dynasty  and are documented in the Chinese pharmacopoeia . Radix Polygoni Multiflori (Heshouwu) is the dried root tuber of Polygonum multiflorum Thunb. (Fam. Polygonaceae) . According to Chinese medicine theory, raw Radix Polygoni Multiflori (R-RPM) counteracts toxicity, cures carbuncles and relaxes the bowels whereas processed Radix Polygoni Multiflori (P-RPM) replenishes the liver and kidney with vital essence and blood, blackens the hair and strengthens the tendons and bones.
R-RPM and P-RPM possess different pharmacological properties. While P-RPM (steamed with black bean juice) enhanced immune activities and anti-immunosuppression, R-RPM did not . R-RPM was purgative whereas P-RPM was not , probably due to lower content of anthraquinones glycosides in P-RPM. R-RPM inhibited triglyceride accumulation induced by carbon tetrachloride (CCl4), cortisone acetate and thioacetamide (TAA) in the mouse liver and P-RPM lowered the triglyceride accumulation induced by cortisone acetate; both R-RPM and P-RPM reduced liver enlargement caused by CCl4.
It is important to differentiate R-RPM from P-RPM because Radix Polygoni Multiflori was linked to hepatotoxicity and other liver conditions [10–15]. Over-the-counter preparations such as Shouwu pian and Shenmin (both containing Radix Polygoni Multiflori) may cause acute hepatitis. A recent study found that, Radix Polygoni Multiflori was the hepatotoxic component that caused acute hepatitis . There were other hepatotoxic cases related to Radix Polygoni Multiflori[17–20]. R-RPM did not induce liver injury  but P-RPM could damage rat's liver after long-term use of high dosages (40 g/kg/day) by intragastric administration. However, no toxic or side effects were found when P-RPM was used at the dosage of 22 g/kg/day which is 10 times of the normal intake for adult per day [22, 23].
Radix Polygoni Multiflori contains anthraquinones (emodin, chrysophanol, physcion, citreorosein, chrysophanol-8-O-β-D- glucopyranoside, physcion-8-O-β-D-glucopyranoside, emodin-8-O-β-D- glucopyranoside, emodin-1,6-dimethylether, questin, questinol, 2-acetylemodin, 2-methoxy-6-acetyl-7-methyljuglone, emodin-8-O-(6'-O-malonyl)-glucoside) [24–26]; stilbene glucosides (2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucopyranoside, 2,3,5,4'- tetrahydroxystilbene-2, 3-O-β-D- glucopyranoside ) and flavonoids (tricin , quercetin-3-O-galactoside, quercetin-3-O-arabinoside ), as well as gallic acid, catechin , torachrysone-8-O-β-D-glucopyranoside , N-transferuloyl tyramine, N-transferuloyl-3-methyldopamine  and 1,3-dihydroxy-6,7 -dimethylxanthone -1-O-β-D-glucopyranoside . There were more free anthraquinones in P-RPM than that in R-RPM. However, anthraquinone glycosides and stilbene glucoside were more abundant in R-RPM than P-RPM . P-RPM contains components not present in R-RPM, namely 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one and 5-hydroxymethyl furfural; P-RPM contains less amino acids and monosaccharides and has a lower pH value than R-RPM .
In recent years, high performance liquid chromatography (HPLC) and gas chromatography (GC) have been employed to determine the level of anthraquinones in Radix Polygoni Multiflori[32, 33].
Using HPLC-DAD and mass spectrometry, the present study compares five pairs of raw and processed Radix Polygoni Multiflori as well as some samples from commercially available decoctions.