| Summary: | 碩士 === 國立臺灣師範大學 === 化學研究所 === 90 === High performance liquid chromatography (HPLC) and capillary electrophoresis (CE) are currently the mostly popularly used analysis methods for assaying the constituents of Chinese herb drugs. By combining the superiorities of both methods, the scope of chemical appraisal of Chinese herb drugs can be expanded. This study is aimed to develop methods for analyzing the tannins of Cinnamomi Cortex and Moutan Cortex, whereby HPLC and CE are compared for their applicability and utility as tools in identifying botanical sources.
In plants, tannins are astringents, which belong to polyphenols, usually referring to those flavonoid phenolic compounds that have molecular weights over 500, and are bonded with protein through a reticular structure or hydrogen bonds. Tannins are chiefly divided into two categories, condensed tannins and hydrolysable tannins.
This study is divided into two parts. The first part deals with the development of HPLC and CE methods for analysis of tannins in Cinnamomi Cortex. Cinnamomi Cortex is the dried stem bark of the Lauraceous plant Cinnamomum cassia Blume, which chiefly contains seven condensed tannins, namely, 1. (+)-catechin, 2. (-)-epicatechin, 3. procyanidin B-1, 4. procyanidin B-2, 5. arecatannin A1, 6. cinnantannin B2, 7. cinnantannin C2. Experimental results show that the seven constituents can be successfully analyzed within 60 minutes, using HPLC with a phosphate eluent, a 5C18-MS column and a detection wavelength at 210 nm. The constituents can also be successfully analyzed within 40 minutes under the MEKC analysis mode with a buffer comprising borate, SC and isopropyl alcohol and a detection wavelength at 210 nm. In the HPLC analysis, the drug material has to be subjected to appropriate pretreatment in order to obtain a good baseline chromatograph. While in the CE analysis, a surfactant (SC) must be added to render good resolution.
The second part of the study deals with the development of HPLC and CE methods for analyses of the tannins in Moutan Cortex. Moutan Cortex is the dried root bark of the Ranunculaceous plant Paeonia suffruticosa Andrew. Using the eight hydrolysable tannins (1. 4,6-di-GG, 2. 1,2,3,6-tetra-GG, 3. 1,2,3,4,6-penta-GG, 4. 1,3,4,6-tetra-GG, 5. 3,4,6-tri-GG, 6. 1,3,6-tri-GG, 7. 3,6-di-GG, 8.1,2,6-tri-GG) in Moutan Cortex as the marker substances, the HPLC method with a phosphate eluent, a 5C18-MS column and a detection wavelength at 280 nm can accomplish the analysis within 60 minutes; and the MEKC method with borate, SDS, isopropyl alcohol and a detection wavelength at 280 nm can finish the analysis within 50 minutes. In the HPLC analysis, the test sample has to be subjected to appropriate pretreatment (Sep-Pak) in order to obtain a good baseline chromatograph, and in the CE analysis, a surfactant (SDS) has to be added to render a good resolution.
In addition, we have collected 13 samples of Szechuanese Moutan Cortex (from Paeonia suffruticosa) and 10 samples of Western Moutan Cortex (from P. delavayi) for chemical identification of herb sources. As a result, there are eight conspicuous peaks of corresponding tannins in Western Moutan Cortex, and there are only seven peaks in Szechuanese Moutan Cortex wherein the constituent 3,4,6-tri-GG (5) is undetectable. The total tannin content is 0.561 ± 0.065 mg/g in Szechuanese Moutan Cortex, and 1.390. ± 0.476 mg/g in Western Moutan Cortex. The greatest distinction between the two is that the PN/Pf ratio is greater than 1 in Szechuanese Moutan Cortex and less than 1 in Western Moutan Cortex; and that the 3/2 ratio is less than 11.4 in Szechuanese Moutan Cortex and larger than 15.2 in Western Moutan Cortex. The above data can be used for the identification of the herb sources of Moutan Cortex articles.
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