Developmental changes in the composition of five anthraquinones from Rheum palmatum as quantified by (1) H-NMR.
BACKGROUND
Rheum palmatum is an important traditional Chinese medicine featuring anthraquinones with several activities. Generally, rhein, emodin, aloe-emodin, physcion and chrysophanol are used as chemical markers for the quality control of rhubarb products.


OBJECTIVE
To develop a simple protocol for the quantification of rhein, emodin, aloe-emodin, physcion and chrysophanol in R. palmatum collected at different developmental stages.


METHODS
(1) H-NMR spectra were measured on samples dissolved in acetone-d6 , quantification was carried out using the signals of H-4 of rhein (δH 8.36), H-7 of emodin (δH 6.68), CH2 OH of aloe-emodin (δH 4.81), OCH3 of physcion (δH 4.02) and CH3 of chrysophanol (δH 2.50), which were well separated from other signals. Quantitative analysis was based on the relative ratio of the intensity of each compound to the known amount of internal standard maleic acid.


RESULTS
The quantitative (1) H-NMR (qHNMR) method developed showed good precision, trueness, linearity, repeatability and stability for the quantification of rhein, emodin, aloe-emodin, physcion and chrysophanol. This method was applied successfully to explore the seasonal variations of the five major anthraquinones in R. palmatum, and provided quantitative results in reasonable agreement with those obtained by the HPLC-UV method.


CONCLUSIONS
Compared with the conventional HPLC-based methods, the qHNMR analysis is rapid, reference-free and convenient with less sample pre-treatment. This technique should be a feasible choice for the quality control of R. palmatum.
State Key Laboratory of Natural Medicines, Department of Natural Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, People's Republic of China.
Zhi-Wei
ZW
Wang
Jun-Song
JS
Wang
Ming-Hua
MH
Yang
Jian-Guang
JG
Luo
Ling-Yi
LY
Kong
D000880:Anthraquinones / Q000032:analysis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004365:Drugs, Chinese Herbal / Q000737:chemistry; D004642:Emodin / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D011786:Quality Control; D015203:Reproducibility of Results; D012250:Rheum / Q000737:chemistry*; D012621:Seasons; D013997:Time Factors
D000880:Anthraquinones; D004365:Drugs, Chinese Herbal; C518327:aloe emodin; C008905:physcione; D004642:Emodin; C027113:chrysophanic acid; C020491:rhein