Therapeutic potential of triterpenoid saponin anemoside B4 from Pulsatilla chinensis

Pulsatilla Decoction (Bai-Tou-Weng-Tang) has been used medically in China for thousands of years for the treatment of diseases caused by bacteria. In recent decades, Pulsatilla Decoction is becoming a well-known formula prescription used for the treatment of ulcerative colitis in traditional Chinese medicine. Pulsatilla chinensis is the chief herbal source of Pulsatilla Decoction, and it is rich in triterpenoid saponins, such as anemoside B4, anemoside A3, and 23-hydroxybetulinic acid. Anemoside B4 is the most abundant of that group and has been used as a quality control marker for Pulsatilla chinensis. As the major active component of Pulsatilla chinensis, anemoside B4 has also received attention as a pure compound for its therapeutic potential. In this review, we systematically analyze the findings on triterpenoid saponins, especially anemoside B4, anemoside A3 and 23-hydroxybetulinic acid, included in Pulsatilla chinensis and Pulsatilla Decoction. We discuss the pharmacokinetics and tissue distribution of these triterpenoid saponins as well as their biological activities. We also summarize the pharmacological effects of anemoside B4 and its two possible metabolites, anemoside A3 and 23-hydroxybetulinic acid, as pure compounds. In summary, this review sketches a profile of the state of existing knowledge with regard to the pharmacological effects of anemoside B4, especially its anti-inflammatory and immunomodulatory effects. These findings point to the possibility that anemoside B4 has potential to be studied further as a natural compound-originated immunomodulatory agent for the treatment of inflammatory diseases such as ulcerative colitis and thus, may represent one of the most important active components of Pulsatilla Decoction responsible for its anti-ulcerative colitis efficacy.