A review of the processed Polygonum multiflorum (Thunb.) for hepatoprotection: Clinical use, pharmacology and toxicology

Ethnopharmacological relevance: Polygonum multiflorum (Thunb.) (PMT) is a member of Polygonaceae. Traditional Chinese medicine considers that the processed PMT can tonify liver, nourish blood and blacken hair. In recent years, the processed PMT and its active ingredients have significant therapeutic effects on nonalcoholic fatty liver disease, alcoholic fatty liver disease, viral hepatitis, liver fibrosis and liver cancer. Aim of the study: The main purpose of this review is to provide a critical appraisal of the existing knowledge on the clinical application, hepatoprotective pharmacology and hepatotoxicity, it provides a comprehensive evaluation of the liver function of the processed PMT. Materials and methods: A detailed literature search was conducted using various online search engines, such as Pubmed, Google Scholar, Mendeley, Web of Science and China National Knowledge Infrastructure (CNKI) database. The main active components of the processed PMT and the important factors in the occurrence and development of liver diseases are used as key words to carry out detailed literature retrieval. Results: In animal and cell models, the processed PMT and active components can treat various liver diseases, such as fatty liver induced by high-fat diet, liver injury and fibrosis induced by drugs, viral transfected hepatitis, hepatocellular carcinoma, etc. They can protect liver by regulating lipid metabolism related enzymes, resisting insulin resistance, decreasing the expression of inflammatory cytokines, inhibiting the activation of hepatic stellate cells, reducing generation of extracellular matrix, promoting cancer cell apoptosis and controlling the growth of tumor cells, etc. However, improperly using of the processed PMT can cause liver injury, which is associated with the standardization of processing, the constitution of the patients, the characteristics of the disease, and the administration of dosage and time. Conclusion: The processed PMT can treat various liver diseases via reasonably using, and the active compounds (2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside, emodin, physcion, etc.) are promising candidate drugs for developing new liver protective agents. However, some components have a toxic-effective bidirectional effect, which should be used cautiously.