Calculus bovis: A review of the traditional usages, origin, chemistry, pharmacological activities and toxicology

Calculus bovis (C. bovis), a widespread known traditional animal drug in China and Japan, has been widely used for a long time to treat various diseases, including high fever, convulsion and stroke. The aim of the present paper is to comprehensively review knowledge about C. bovis in terms of traditional usages, origin, chemical constituents, pharmacological activities and toxicology to seek an applicable substitute for NCB and provide potential new strategies utilizing C. bovis. Additionally, directions and perspectives for future investigations regarding C. bovis are also discussed. In this paper, the traditional usages, origin, chemical constituents, pharmacology, and toxicology of C. bovis are comprehensively and systematically summarized by searching scientific databases, including Web of Science, PubMed, ScienceDirect, Springer, CNKI, Baidu Scholar and others. Additionally, some classic books of Chinese herbal medicine, academic papers authored by individuals with MSc and PhD degrees, local government reports as well as the state of local drug standards are also retrieved. Currently, C. bovis mainly derives from four sources: natural Calculus bovis (NCB), Calculus bovis sativus (CBS), Cultured calculus bovis (CCB) and Calculus bovis artifactus (CBA). Owing to their different formation processes, the chemical constituents of the four kinds of C. bovis show certain differences. Additionally, over 44 chemical constituents have been isolated and identified from C. bovis, mainly including bile pigments, bile acids, cholesterols and amino acids. Further investigations have revealed a wide range of pharmacological effects of C. bovis, with effects on the nervous system, cardiovascular system, respiratory system, digestive system, immune system and others. Furthermore, NCB and CBA show hypotoxicity, but high concentrations of bilirubin can cause neurotoxicity and hearing impairment. Additionally, pharmacokinetic data for C. bovis are still lacking. CBS contains analogous types and amounts of constituents and exerts similar therapeutic effects to NCB. Thus, CBS might be used as a sustainable substitute for NCB. Furthermore, the configuration and concentration of bile acids and bilirubin in C. bovis are responsible for the difference in pharmacological effects in the four types C. bovis. Further studies should focus on the structure-function relationship of bile acids and bilirubin in C. bovis by employing pharmacokinetics.