| The major difference between traditional Chinese herbs and natural herbs is that most of Chinese herbs can only be used after processing.The process can change Chinese herbs in properties,and property changes should result from the changes in chemical compounds.The root of Polygonum multiflorum Thunb.(PM) has been used in two forms in traditional Chinese medicine:direct dried called the root of PM(Heshouwu in Chinese) and processed with steaming method called the processed root of PM(Zhi-heshouwu in Chinese).The root of PM has been used as detoxication and purgation;and the processed one has been used as tonicity and nutrition.The pharmacological studies have also shown that these two preparations have different activities,which must be resulted from their different chemical components.There are three methods for the processing of the root of PM according to the Chinese Pharmacopeia,steamed with black bean sauce,steamed with water and stewed with black bean sauce.The processing time is uncertain,which is from 3 h to 40 h in different provinces. In this paper,the contents of chemical components including emodin,physcion,conjugated anthraquinone,2,3,5,4'-tetrahydro- xystilbene-2-O-β-D-glycoside,tannin,galic acid,catechin were investigated after the root of PM were processed in the above three methods for different time.The results showed that the contents of active components were the highest in the samples processed with stewed with black bean sauce for 32 h.New chromatographic peak in HPLC was found in the processed root of PM compared to the dried one.From 0.298 min to 0.331 min at the relative time,a new chromatographic peak was detected at the processed root of PM,which indicated that new components might be formed after steaming.The compounds were in a dynamic variation during steaming process. The new compounds were isolated and identified,and their originations were elucidated as Maillard reaction based on comparative analyses of contents of new generated components, amino acid,sugar and pH value between the dried and the processed root of PM.The Maillard reaction is a series of reaction between amino compounds,usually amino acids or proteins, and carbohydrates.Maillard reaction products possess antioxidant activity,chemopreventive activity,anti-mutagenic activity,etc.Nine other compounds were detected by GC-MS analysis at the processed root of PM and they were Maillard compounds too.They showed anti-oxidative activity by exterminating the scavenging effect on DPPH and OH radicals.Sixteen compounds were isolated and identified from the processed root of PM as 2,3-dihydro-3,5-dihydroxy-6-methyl-4(H)-pyran-4-one(1),hydroxymaltol(2),5-hydroxy-methyl-furfuran(3),butanedioic acid(4),1,4-benzenediol(5),p-hydroxybenzaldehyde(6), gallic acid(7),2,3,5,4'-tetrahydroxy- stilbene-2-O-β-D-glucoside(8),citreorosein(9),questin (10),questinol(11),2-methoxy-6-acetyl- 7-methyljuglone(12),emodin(13),physcion(14), emodin-8-O-β-D-glucoside(15) and physcion-8-O-β-D-glucoside(16).Among them, compounds 1-5 were found in this plant for the first time,and compounds 1-4 were produced after processing and they were Maillard compounds.The analytic methods for discriminating the root of PM and the processed one were established using thin layer chromatography(TLC) and rapid resolution liquid chromatography(RRLC).The best processing method for the root of PM was determined as stewed with black bean sauce for 32 h according to the contents of active compounds and the results of pharmacodynamic experiments comparing to the traditional processing method.Maillard reactions were in the heating processing periods of many Chinese herbs which were testified by GC-MS analysis and the Maillard compounds were different.
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