Uses, chemical compositions, pharmacological activities and toxicology of Clematidis Radix et Rhizome- a Review

Clematis chinensis Osbeck (C. chinensis), Clematis hexapetala Pall (C. hexapetala) and Clematis terniflora var. mandshurica Rupr (C. mandshurica) are collectively referred to as Clematidis Radix et Rhizome (CRR) in China. CRR is widely distributed in China, which is used as a traditional Chinese medicine to treat rheumatic arthralgia, limb numbness, tendon constriction and inconvenience in flexion and extension.This review systematically summarized the research progress on uses, chemical components, pharmacological activities and toxicology of CRR, listed the chemical structures of main compounds for clarifying the differences in chemical compositions. Meanwhile, the review will provide a theoretical and practical basis for the further research and development of CRR.The available information on CRR was collected using published materials and electronic databases, including ancient and modern books, Chinese Pharmacopoeia, Ph.D. and M. Sc. dissertations, CNKI, SciFinder, WanFang data, PubMed, ScienceDirect and Web of Science. The starting and ending years of references is 1965-2020, the search strategy was conducted by key words such as uses, chemical components, pharmacology and toxicology of CRR.Up to now, CRR has been used to treat various diseases/disorders, such as relieving rheumatism pain, treating cervical spondylopathy and scapulohumeral periarthritis, treating hepatic carcinoma and gastrointestinal, etc. In addition, more than 200 compounds have been isolated from the three plant species of Clematidis. Moreover, the crude extracts and isolated compounds of CRR have been reported to have a wide range of pharmacological activities, such as anti-inflammatory, anti-tumor, antimicrobial and antioxidant activities, etc. Toxicity studies have shown that CRR can cause oral burning, swelling, abdominal pain or severe diarrhea, difficulty breathing, dilated pupils, renal tissue structural changes, and severe death.Researches in recent years mainly focused on C. chinensis and C. mandshurica, while there are a few reports on the pharmacological studies of C. hexapetala. Therefore, it is necessary to conduct further research on C. hexapetala. Meanwhile, it is important to pay attention to pursue research on the similarities and differences between the three plant species of Clematidis to find their respective advantages and make rational use of CRR. In addition, there is no report on the mechanism of toxicity research, which needs more attention.