ABSTRACT
Tianma(the tuber of Gastrodia eleta) is a widely used and pricy Chinese herb. Its counterfeits are often found in herbal markets, which are the plant materials with similar macroscopic characteristics of Tianma. Moreover, the prices of Winter Tianma(cultivated Tianma) and Spring Tianma(mostly wild Tianma) have significant difference. However, it is difficult to identify the true or false, good or bad quality of Tianma samples. Thus, a total of 48 Tianma samples with different characteristics(including Winter Tianma, Spring Tianma, slice, powder, etc.) and 9 plant species 10 samples of Tianma counterfeits were collected and analyzed by HPLC-DAD-MS techniques. After optimizing the procedure of sample preparation, chromatographic and mass-spectral conditions, the HPLC chromatograms of all those samples were collected and compared. The similarities and Fisher discriminant analysis were further conducted between the HPLC chromatograms of Tianma and counterfeit, Winter Tianma and Spring Tianma. The results showed the HPLC chromatograms of 48 Tianma samples were similar at the correlation coefficient more than 0.848(n=48). Their mean chromatogram was simulated and used as Tianma HPLC fingerprint. There were 11 common peaks on the HPLC chromatograms of Tianma, in which 6 main peaks were chosen as characteristic peaks and identified as gastrodin, p-hydroxybenzyl alcohol, parishin A, parishin B, parishin C, parishin E, respectively by comparison of the retention time, UV and MS data with those of standard chemical compounds. All the six chemical compounds are bioactive in Tianma. However, the HPLC chromatograms of the 10 counterfeit samples were significantly different from Tianma fingerprint. The correlation coefficients between HPLC fingerprints of Tianma with the HPLC chromatograms of counterfeits were less than 0.042 and the characteristic peaks were not observed on the HPLC chromatograms of these counterfeit samples. It indicated the true or false Tianma can be identified by either the similarity or characteristic peaks on HPLC fingerprint. Comparing the Winter Tianma with Spring Tianma showed that the HPLC chromatograms of 15 winter Tianma samples and 11 spring Tianma samples were similar at the mean correlation coefficient of 0.908. But the intensity of the characteristic peaks were different between the two groups of Tianma samples, i.e. the intensity of gastrodin, paishin A and C in winter Tianma was lower than those in spring Tianma. The Winter Tianma and Spring Tianma could be discriminated by either the Fisher unstandardized discrimination function or Linear discriminant function, based on the peak areas of 11 common peaks on HPLC chromatograms as variate.
ABSTRACT
Objective: To study the correlation between the contents of gastrodin and polysaccharides with the variety of commercial specifications, grades, and cultivated areas of Gastrodia Tuber (Tianma), the tuber of Gastrodia elata, and then to choose the suitable chemical marker to assess the quality of Tianma raw materials. Methods: Gastrodin and polysaccharides were quantified in 35 Tianma samples including Winter Tianma which was harvested in winter, Spring Tianma which was harvested in spring with their different grades and cultivation areas by HPLC and spectrophotometry, respectively. Combined with the morphological characteristics, the correlation between the various Tianma samples with the amounts of gastrodin and polysaccharides was studied. Results: The content of polysaccharides in Winter Tianma (26.05%, n = 24) was higher than that in Spring Tianma (20.21%, n = 10). In contrast, the amount of gastrodin in Winter Tianma (0.49%, n = 24) was lower than that in Spring Tianma (0.68%, n = 10). Among Tianma samples with different grades, the content of polysaccharides in the first grade (32.65%, n = 6) and second grade (32.89%, n = 6) was higher than that in the third grade (21.71%, n = 8) and fourth grade samples (14.57%, n = 4). But, the amounts of gastrodin in the Tianma samples of the four grades were similar, which were 0.46% (n = 6), 0.65% (n = 6), 0.43% (n = 8), and 0.44% (n = 4) in the first, second, third, and fourth grade Tianma, respectively. Moreover, the contents of gastrodin and polysaccharides in Tianma samples collected from the famous cultivation regions such as Sichuan, Shaanxi, and Yunnan provinces of China were higher than those from others areas. Conclusion: The developed HPLC and spectrophotometry methods are accurate and reliable to assay the amounts of gastrodin and polysaccharides in Tianma. The amount of polysaccharides is related to the quality of Tianma samples authenticated by the commercial specifications, grades, and traditional experience, and therefore is a better marker to assess the quality of Tianma.