Studies On Chemical Constituents And Quality Control Of Rhubarb (Ⅱ)

Gaoshandahuang is the dried radix and rhizome of Rheum nobile Hook.F.et Thoms or Polygonum sibiricum Laxm recorded in Chinese Herbalism. Rheum nobile Hook. f. et Thoms is a 1～2 m high perennial herb (Polygonaceae), occurring in 4000-4800 meters attitude of Himalayas and northwest of Yunnan, China. Its rhizomes are used in Tibetan medicine for the treatment of edema caused by kidney problem, and "yellow water" diseases.In Tibetan medicine, "yellow water" is considered as one of the components of human body, it can cause skin, joint, and viscera diseases if it is imbalanced.Previous studies found that Gaoshandahuang contain anthraquinones and stilbene glycoside constitutents in mayor. This review summaried the chemical constituents, biological activities and quality control methods of anthraquinones and stilbene glycoside compounds.The chemical constituents of Rheum nobile Hook.f. et Thoms were isloated by column chromatography, including silica gel, Sephadex LH-20 and preparative HPLC.17 compounds’ structures were determined by combined ESI-MS, NMR and comparison of their spectral data to those previously published. They are Physcion-8-O-β-D-glucopyranoside(1), Emodin-8-O-β-D-glucopyranoside(2), Chrysophanol-8-O-β-D-(6’-acetyl)-glucopyranoside(3), Chryso pha-nol-1-O-β-D-glucopyranoside(4), Chrysophanol-8-O-β-D-glucopyranoside(5), Chrysa-loin A (6a), Chrysaloin B (6b), Emodin (7), Chrysophanol (8), Physcion (9) Piceatannol-4’-O-β-D-glucopyranoside(10), and Resveratrol-4’-O-β-D-glucopyranoside(11), 2,5-dimethy-7-hydroxychromone-7-O-β-D-glucopyranoside (12), Aloesone-7-O-β-D-gluco-pyranoside (13), Syringin (14), (-)-Epicatechin (15), Torachrysone -8-O-β-D-glucopyranoside (16). Compounds 6a,6b and 14 were firstly isolated from Rheum, while 3,4,12 and 13 were isolated from Rheum nobile Hook.f.et Thoms for the first time.A method for preparation of piceatannol-4’-O-β-D-glucopyranoside has been established. The purity is over 98% by detecting with HPLC methods. This paper also evaluated the stability of piceatannol-4’-O-βD-glucopyranoside and found that it is vulnerable to humidity and sensitive to high temperature. Piceatannol-4’-O-β-D-glucopyranoside should be stored at lucifugal, dried and hypothermal environments.In this research, structure characters and morphological identification of Rheum nobile were described and illustrated. There are large numbers of lignified vessels in the raw powders. Ten batches of the herb powders were identified by thin layer chromatography(TLC) and used piceatannol-4’-O-β-D-glucopyranoside as the reference substance. The spots of piceatannol-4’-O-β-D-glucopyranoside of ten batches were clear and well separated.The paper also studied the moisture content, total ash and acid-insoluble ash. The content of moisture of 10 batchs were range from 7.46% to 9.14%, the total ash were 2.72%-8.75%, and the acid- insoluble ash were 0.50%-2.51%.A quantitative method was firstly established for the determination of anthraquinones by ultraviolet spectroscopy (UV). This paper used emodin as reference substance,1% Mg(CH3COO)2 as Chromogenic agent. The regression equation of anthraquinones is y= y=36.76x+0.0027 (r=0.9998) and the linear range are 2.28-22.80μg/mL. The average recoveries are 98.80% with RSD of 1.81%. This method is precision, repeatability and stability. Anthraquinones of the ten batchs of Rheum nobile are 2.02%～5.67%.