黃芩成分之分析與基原之辨識

葉政洳(Chen-Ru Yeh)

指導教授 ： 許順吉

國立臺灣師範大學/理學院/化學系/碩士(1999年)

摘要

高效液相層析(HPLC)係為一種液相分離技術，其常被使用於分析及定量中藥材中的指標成分，本研究的第一部份在於開發黃芩藥材的HPLC分析方法，並利用此HPLC分析方法進行黃芩基原的化學辨識。
黃芩為常用中藥材，具有清熱燥濕、瀉火解毒之效。黃芩中的重要指標成分為六種黃酮類化物(flavonoids)，分別為baicalin(BG)、wogonin 7-O-glucuronide(WG)、oroxylin A 7-O-glucuronide(OG)、baicalein(B)、wogonin(W)以及 oroxylin A(O)。在黃芩的HPLC分析方法中，流動相(A)為20 mM KH2PO4，並以10%H3PO4調整pH值至3.23；流動相(B)為CH3CN/H2O = 80/20(v/v)，使用Cosmosil 5C18-MS 為分析管柱，以280 nm 為偵測波長。如此可在梯度衝題系統下，在60分鐘內分析六種指標成分。
此外，本研究以黃芩(Scutellaria baicalensis Georgi)、粘毛黃芩( S. viscidula Bge.)及台灣市售黃芩飲片等共59批，進行黃芩基原之化學辨識。研究發現黃芩中六種成分皆有明顯吸收峰，粘毛黃芩的非糖體部分則幾乎無法偵測；黃芩中黃酮體總量為(280.25±64.45 mg/g) ，粘毛黃芩則為(218.91±46.03 mg/g)；黃芩中OG/WG含量比為＜0.56，粘毛黃芩則為＞27.95；黃芩中BG/OG的含量比係＞1.37，粘毛黃芩則為＜1.44。根據以上數據，可做為辨識黃芩基原時的參考依據。此部份最後並對黃芩藥材之安定性加以評估，探討黃芩?谷b各種環境下，對BG、B兩成分間含量消長的影響。
本研究的第二部分在於延續桂類藥材(桂枝、桂皮)之HPLC及MEKC分析方法，並解決其低萃出率的問題。在眾多線上樣品堆積技術中，擇出一種適合中性物質的方法，稱為掃集法(sweeping)。在此分析方法中，緩衝溶液係為含100 mM SDS之50 mM 磷酸溶液，並加入10%甲醇(pH = 1.62 cond.= 6.03)。如此可在25分鐘內分離桂枝中的cinnamic acid(Acid)、cinnamaldehyde(Ald)、cinnamyl alcohol(Alc)、coumarin(Cum)等四種精油類成分，並得到比HPLC及MEKC更低的偵測極限。
但在放大倍數的研究中，發現同時含四種精油類成分的標準溶液，其放大效應並不理想。因此選擇藥材中含量最多之Ald，以及做為對照組的naphthalene，討論兩者的放大效應。結果發現濃度皆在偵測極限附近的兩者，其中Ald可放大約 100 倍，而naphthalene則可放大約 1000 倍。放大效應係與分析物之結構有關，因為結構可影響分析物的滯留因素及疏水特性，亦即本分析方法對滯留因素較大且較具疏水性的分析物，有較佳之放大效果。

關鍵字

黃芩 ； HPLC ； 基原辨識 ； 桂枝 ； sweeping

並列摘要

Abstract
High-performance liquid chromatography(HPLC) is a well-known technology and is commonly used to quantitatively analyse the marker components in conventional Chinese herbal drugs. The first section of this study, a HPLC method for Scutellariae Radix was established, and the method was successfully used to postulate the origin of the herb drug.
Scutellariae Radix is a commonly used Chinese herbal drug possessing the effects of clearing heat、moistening aridity、purging fire and detoxifying toxicosis , and contains baicalin(BG)、wogonin 7-O-glucuronide(WG)、oroxylin A 7-O-glucuronide(OG)、baicalein(B)、wogonin(W) and oroxylin A(O) as their major bioactive components. The RP-LC method was carried out within 60 minutes by using a Cosmosil C18-MS column and a gradient solvent system of acetonitrile-
phosphate buffer, and detecting at 280 nm.
A total of 59 commercial samples of Scutellariae Radix which originated from Scutellaria baicalensis Georgi and S. viscidula Bge. were collected from the Taiwan and Mainland China herbal markets. It was found that the contents of scute flavonoids in S. baicalensis (280.25±64.45 mg/g) were superior to those in S. viscidula (218.91±46.03 mg/g) ; the ratio of OG/WG was 0.56 for the former and 27.95 for the latter ; the ratio of BG/OG was more than 1.44 for the former and less than 1.37 for the latter. From the data on the chemical analysis of the herb`s constituents , we can postulate the origin and quality of a herb drug.
The second section of this study is to continue the HPLC and MEKC method in analyzing the bioactive constituents in Cinnamomi Ramulus. Furthermore, we expect to solve the puzzles of the difficulty in Cinnamomi Ramulus to be efficiently extracted.
In our search for ways to improve the concentration sensitivity by sample stacking in MEKC separation mode, we found a new method termed as〝sweeping〞.With this method, the four marker components of Cinnamomi Ramulus : cinnamic acid(Acid), cinnamaldehyde(Alde), cinnamyl alcohol(Alc), coumarin(Cum),could be analyzed within 25 minutes by using a buffer system containing 100 mM SDS in 50 mM phosphoric acid and 10% methanol (pH = 1.62, cond. = 6.03 mS/cm).
By comparing with HPLC and MEKC method, we found that the concentration sensitivity was improved.
But in studying the enhancement effect, we failed to enlarge the signal of the standard solution containing four marker components. So, we choose Ald, the main portion of the constituents of Cinnamomi Ramulus, and naphthalene for comparison to valuate the enlargement effect in sweeping.
As a result, it was found that Alde could be enlarged to about 100 folds, and naphthalene could be enlarged to about 1000 folds. Enhancement effect is based on the structure of analytes, which affects the capacity factor and the hydrophobic character of analytes. That is, for a neutral analyte with higher capacity factor and more hydrophobic character , it will perform a more efficient enlargement effect in the sweeping method.

並列關鍵字

Scutellaria baicalensis Georgi ； HPLC ； comparative study ； Cinnamomi Ramulus ； sweeping

參考文獻

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