大黄干燥方法研究

Study on drying methods of Rhei Radix et Rhizoma

目的以大黄外观色泽、干燥耗时、折干率和有效成分的量为指标,考察大黄适宜的干燥方式。方法供试用大黄品种为掌叶大黄,外观色泽考察依据《中国药典》2010年版;用热浸法提取浸出物;HPLC法测定蒽醌、儿茶素和没食子酸的量。结果低于65℃烘干、阴干、晒干和熏干的大黄色泽良好,断面呈黄棕色,而高于65℃烘干的大黄药材断面深棕色;在大黄有效成分方面,浸出物和蒽醌的量以晒干大黄为最高,分别为34.32%和1.90%,次之为45℃烘干大黄,分别为33.53%和1.68%;干燥温度过高,蒽醌的量显著降低;不同温度的恒温烘干处理中,随着温度的升高,没食子酸和儿茶素的量均呈递减趋势。结论大黄适宜的干燥方法是45℃恒温烘干或晒干。

Objective To explore the suitable drying methods for Rhei Radix et Rhizoma （RRR） with color, drying time, drying rate, and content of active ingredients as indexes. Methods Rheum palmatum was used in the test and the color of RRR was studied according to Chinese Pharmacopeia 2010. The extract was obtained by hot-dip method. The contents of anthraquinone, gallic acid, and catechin were determined using HPLC. Results RRR treated with oven-drying, shade-drying, sun-drying, and fumigated with sulfur-drying below 65 ℃ showed good color and the cross-section was claybank. The cross-section of RRR treated with oven-drying over 65 ℃ showed dark brown. The highest contents of extract and anthraquinone in RRR treated by sun-drying were 34.32% and 1.90% and followed by those treated by oven-drying at 45 ℃ with 33.53% and 1.68%, respectively. High temperature caused the decrease of anthraquinone in RRR. The contents of gallic acid and catechin reduced with the increase of temperature under the constant temperature oven-drying process. Conclusion The suitable drving method for RRR is oven-drying at constant 45℃ or sun-drying.