Chem. Pharm. Bull. 54(11) 1491—1499 (2006)

widely known as a purgative and anti-inflammatory agent. In Chinese Pharmacopoeia, the official Dahuang is prescribed as the dried rhizome and root of Rheum palmatum L., R. tanguticum MAXIM. ex BALF., and R. officinale BAILLON of the family Polygonaceae. On the other hand, the Japanese Pharmacopoeia prescribes not only the above three species but also R. coreanum NAKAI, and their interspecific hybrids as the botanical origin for Rhei Rhizoma. Rheum plants are self-incompatible in nature, therefore random hybridization results in morphological intermediate forms in the shape of leaf blade, type of inflorescence, color of flowers, etc. This situation makes the taxonomic identification of Rheum plants very difficult. In recent years, quality degradation of Rhei Rhizoma that affects therapeutic efficacy was pointed out by Japanese Kampo doctors. As factors affecting the difference of chemical constituent composition and contents, many reasons such as genetic distinction, botanical sources, production areas, harvest time, processing method, etc., are considered. Kashiwada et al. reported the characteristic constituent pattern in Rhei Rhizoma produced in Qinghai and Sichuan Provinces; however, their botanical sources were not demonstrated due to the lack of suitable identification methods. In our previous paper, chloroplast matK gene sequence of Rheum plants was found a useful index to differentiate species and to deduce the production areas. Subsequently, by comparing nucleotide sequences of Rhei Rhizoma with those of Rheum species, the botanical origins of 22 rhubarb samples were determined. On the other hand, for quantitative control of Rhei Rhizoma, HPLC methods to analyze 30 bioactive constituents have been developed. In the present paper, quantitative analysis of 30 constituents of a total of 24 rhubarb samples obtained from Qinghai, Sichuan, Yunnan, and Gansu Provs. of China and from Japan was further performed to clarify the quality of marketing samples. Previously, consistency between the similarity of chemical constituent pattern and genetically close relatives of various taxa has been observed within the genera Panax, Glycyrrhiza, and Psilocybe. Herein, we also investigate the relationship between chemical constituent patterns and genetic variation.