Quality Analysis of Raw Material and Products of Goat Bezoar (Houzao), a Mysterious Traditional Medicine

Background: Goat bezoar (Houzao in Chinese, also called “monkey” bezoar or Caprae Calculus) is a valued traditional Chinese medicine (TCM) used in the treatment of pediatric cough for centuries. However, its undefined chemical composition hinders quality control and mechanistic understanding, limiting its modernization and further development.

Objective: This study aims to comprehensively characterize the chemical composition of goat bezoar and develop a robust quality control method.

Method: UPLC-qTOF-MS was first utilized to analyze the methanol extract of goat bezoar reference material. Markers specific to the medicinal portion were identified by comparing the chemical profiles with the non-medicinal portion and 50 co-formulated TCMs. Amino acid composition and ash content were also determined. Validated quantitative methods for these markers were subsequently developed using both UPLC-qTOF-MS and UPLC-DAD and applied to assess the quality of 13 batches of raw goat bezoar material and 38 batches of commercial products.

Results: Eight characteristic markers, including ellagic acid and seven of its gut microbial metabolites (urolithins), were identified exclusively within the medicinal portion. Ellagic acid (72.72%–89.41%) and total urolithins (2.14%–5.13%) were major components. These, along with amino acids (1.19%–5.91%) and total ash (2.09%), account for over 90% of the medicinal portion's composition. The analysis of commercial materials and products using this method revealed that goat bezoar may be absent in 20 commercial products while all the goat bezoar powder samples were authentic.

Conclusion: This study provides the first comprehensive chemical characterization of goat bezoar, revealing its unique composition and establishing it as the only known TCM with urolithins. Validated quantitative methods for ellagic acid and urolithins provide a crucial quality control tool, paving the way for further research, development, and modernization of this valuable TCM.