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Pressurized steam as valuable extraction option to produce TCM decoction
Decoction is one of the major forms of preparing drugs in traditional Chinese medicine (TCM). The traditional procedure consists of two boiling steps of the drug in a suitable vessel . However, other machines such as pressure cookers are coming into discussion to prepare decoctions, e.g. for small-scale industry. The focus of this study was on the preparation of decoctions in pressurized steam, especially on the resulting extraction yields and the time needed for preparation. These findings were compared to conventional decoctions prepared in a simple vessel on a hotplate, or with an electric brewing pot. The experiment was carried out with the TCM drug aged tangerine peel (Chenpi, Citri reticulatae pericarpium), which contained hesperidin in the amount of 89.1mg/g (=100%) in the herbal drug. Quantification was performed by HPLC analysis . The results of the pressurized steam process (small autoclave, 1h-1h 40min, at 120°C) showed a yield of hesperidin in the range of 6.2–9.7%. By contrast, a conventional decoction (1h soaking, and 40+20min decoction) yielded only 3.4–3.9% of hesperidin, and a decoction in a brewing pot lasting 2h, showed similarly low yields of hesperidin, namely 3.0–3.3%. The present study showed that preparations of aged tangerine peel, Chenpi, extracted inpressurized steam contained a more than twofold amount of hesperidin, compared to decoctions obtained by a conventional TCM procedure. Whether these findings could be generalized to other substances than hesperidin, or other drugs, will be the subject of further investigation.
Acknowledgements: We would like to thank Lian Chinaherb, Switzerland, for the supply of herbal drug material as well as SWISSMEDIC, Swiss Agency for Therapeutic Products, Pharmacopoeia division, for the financial support.
References: 1. EDQM (2010): Preparation of drugs for traditional Chinese medicines, In: Pharmeuropa 22.2 2. EDQM (2007): Mandarin epicarp and mesocarp (draft monograph), In: Pharmeuropa 19.1.