Oral administration of leeches (Shuizhi): A review of the mechanisms of action on antiplatelet aggregation

Ethnopharmacological relevance: The leeches (Shuizhi) comprise approximately 680 species distributed throughout the world. As recorded, they have been used as traditional Chinese medicines since the Eastern Han Dynasty, where they were claimed for promote blood circulation and eliminate blood stasis. And have been used to prevent CVDs by exerting multiple effects when orally administered, one of which is the significant inhibition of platelet aggregation. Its ability to exert this effect has been extensively investigated in vivo and in clinical practice. Aim of study: The aim of this review is to summarize and analyse the antiplatelet aggregation mechanisms of leeches by oral administration, support their therapeutic potential and uncover opportunities for future research. Materials and methods: Relevant studies from 1980 to 2018 on leeches and platelet aggregation were collected from ancient books, pharmacopoeia, reports and theses via library and internet databases (PubMed, CNKI, Google Scholar, Web of science, SciFinder, Springer and Elsevier). Results: Leeches is a unique animal medicine, they can prevent platelet aggregation by inhibiting ADP-induced platelet aggregation, increasing PGI2, decreasing TXA2 and Cat, and possibly recovering endothelial cell dysfunction. Leeches also exhibit a strong ability to activate eNOS, leading to an increase in platelet-derived NO. Additionally, the pteridine compounds obtained and identified from leeches have sulfur structure similar to those of other antiplatelet aggregation agents, such as ticlopidine, clopidogrel and ticagrelor. Conclusion: The present review has focused on the related antiplatelet aggregation mechanisms, dipyridine compounds and toxicological information of leeches. According to the reported data, leeches have emerged as a good source of natural medicine for the treatment of antiplatelet aggregation agents and also make educated guesses for material basis of effects on antiplatelet aggregation. This review can help provide new insights for further studies in association with the development of effective antiplatelet aggregation drugs from natural medicines, especially leeches.