What is the cooking time for Da Huang to achieve a purgative effect?

What is the cooking time for Da Huang to achieve a purgative effect?

• A. No more than 15 minutes
• B. No more than 10 minutes
• C. No limit
• D. At least 15 minutes

Answer: (B)

Da Huang’s purgative action is achieved with a brief decoction. The potent hydroxyanthraquinone compounds that drive the purge are extracted quickly into water, so a short simmer (about 5–10 minutes) is sufficient. Extending the cooking time tends to alter the extraction balance, potentially reducing the purgative potency and increasing irritation from other constituents. Therefore, to obtain the purgative effect, the preparation should be cooked no longer than about 10 minutes.

Da Huang’s purgative action is achieved with a brief decoction. The potent hydroxyanthraquinone compounds that drive the purge are extracted quickly into water, so a short simmer (about 5–10 minutes) is sufficient. Extending the cooking time tends to alter the extraction balance, potentially reducing the purgative potency and increasing irritation from other constituents. Therefore, to obtain the purgative effect, the preparation should be cooked no longer than about 10 minutes.