Studies Of HPLC Fingerprint Chromatography And Chemical Constituents Of Rhubarb

Rhubarb is a very famous Traditional Chinese Medicine recorded first in a herbal book-"Shennong Bencao Jing", then in every edition of "Bencao" and Chinese Pharmacopoeias. It has been used most frequently for its various pharmacological actions such as purgation, antifungal and antitumor.Recognized and recorded in the Chinese Pharmacopoeia (2000), rhubarb is the dried rhizome and radix from three species, Rheum palmatum L., R. tanguticum Maxim, ex Balf. (R. palmatum L. var. tanguticum Maxim.) and R. officinale Baill., Polygonaceae family. The plants of Rheum genus is mainly distributed in Asia, specially distributed in West China, In recent years, the wild resources of rhubarb have annually decreased due to overexploiting, that causes some adulterant species to appear as "official" rhubarb in the market. In this paper, botanical origins, external structures and microscopic characters of the three "official" rhubarb have been studied to distinguish them from the "unofficial" ones.A HPLC/UV method was used to establish an accurate and reproducible chromatography fingerprint spectrum for Rheum palmatum L. planted in Kangding County, Sichuan Province. The method has also been applied tocompare the differences with species, plant ages, producing areas, processing methods and different parts of the plant. The method has been proved to be a practical one to control the quality of rhubarb from its GAP(Good Agricultural Practice) base.According to the Chinese Pharmacopoeia (2000), a HPLC/UV method was applied to compare contents of emodin and chrysophanol in rhubarb of different species, different plant ages, different producing areas, different methods and different parts of the plant. The results indicate that proper planting methods should be taken to improve the quality of rhubarb, rhubarb cultivated in Kangding County for three years can be harvested and should be processed in time to ensure its quality. And the seed of the plant may be exploited properly.Through low-pressure LC, TLC, five compounds have been isolated from rhizome of Rheum palmatum L.. Their structures have been elucidated as chrysophanol(l), physcion(2), emodin(3), Aloe-emodin(4), and d-catechin(5) by spectral analysis such as 'H-NMR, 13C-NMR and MS.