School of Life Science and Chemical Engineering, Huaiyin Institute of Technology, Jiangsu, China.
Pharm Biol. 2013 Oct;51(10):1228-35. doi: 10.3109/13880209.2013.784922. Epub 2013 Jun 5.
Scutellaria baicalensis Georgi (Labiatae) is one of the most commonly used medicinal herbs, especially in traditional Chinese medicine. However, compared to many pharmacological studies of this botanical, much less attention has been paid to the quality control of the herb's pretreatment prior to extract preparation, an issue that may affect therapeutic outcomes.
The current study was designed to evaluate whether different pretreatment conditions change the contents of the four major flavonoids in the herb, i.e., two glycosides (baicalin and wogonoside) and two aglycones (baicalein and wogonin).
A high-performance liquid chromatography assay was used to quantify the contents of these four flavonoids. The composition changes of four flavonoids by different pretreatment conditions, including solvent, treatment time, temperature, pH value and herb/solvent ratio were evaluated.
After selection of the first order time-curve kinetics, our data showed that at 50 °C, 1:5 herb/water (in w/v) ratio and pH 6.67 yielded an optimal conversion rate from flavonoid glycosides to their aglycones. In this optimized condition, the contents of baicalin and wogonoside were decreased to 1/70 and 1/13, while baicalein and wogonin were increased 3.5- and 3.1-fold, respectively, compared to untreated herb.
The markedly variable conversion rates by different pretreatment conditions complicated the quality control of this herb, mainly due to the high amount of endogenous enzymes of S. baicalensis. Optimal pretreatment conditions observed in this study could be used obtain the highest level of desired constituents to achieve better pharmacological effects.
黄芩（唇形科）是最常用的草药之一，尤其是在传统中药中。然而，与该植物许多药理学研究相比，对草药预处理以制备提取物的质量控制关注较少，这可能会影响治疗效果。
本研究旨在评估不同预处理条件是否会改变草药中四种主要黄酮类化合物的含量，即两种糖苷（黄芩苷和汉黄芩苷）和两种苷元（黄芩素和汉黄芩素）。
采用高效液相色谱法测定这四种黄酮类化合物的含量。评估了不同预处理条件（溶剂、处理时间、温度、pH 值和药材/溶剂比）对四种黄酮类化合物组成的变化。
在选择一阶时间曲线动力学后，我们的数据表明，在 50°C、1:5 药材/水（w/v）比和 pH 6.67 下，黄酮苷转化为苷元的转化率最佳。在这种优化条件下，黄芩苷和汉黄芩苷的含量分别降至未处理药材的 1/70 和 1/13，而黄芩素和汉黄芩素的含量分别增加了 3.5 倍和 3.1 倍。
不同预处理条件下转化率的显著变化使该草药的质量控制复杂化，主要是由于黄芩中内源性酶的含量较高。本研究中观察到的最佳预处理条件可用于获得所需成分的最高水平，以达到更好的药理效果。
