Traditional uses, phytochemistry, and pharmacology of Persicaria orientalis (L.) Spach - A review

Ethnophatmacological relevance: Persicaria orientalis (L.) Spach (internationally accepted and only valid name; synonym: Polygonum orientale L.; family: Polygonaceae), which is named Hongcao in China, is a Chinese herbal medicine that has a wide range of pharmacological effects including treatment to rheumatoid arthritis, coronary heart disease, hernia, carbuncle sore, enhance immunity, antimicrobial, osteogenic and dilated bronchiectasis. Aim of this review: This review aims to provide systematically organized information on traditional uses of Persicaria orientalis (L) Spach (P. orientalis) and to critically analyze evidences in phytotherapeutic, botanical, and pharmacological literatures that support its therapeutic potential in treatment to human diseases. Isolation of additional compounds and detailed pharmacological investigations are key areas to investigate. Materials and methods: Relevant information on P. orientalis was collected through published scientific materials (including PubMed, ScienceDirect, Wiley, ACS, CNKI, Scifinder, Springer, Taylor & Francis, Web of Science, Google Scholar, and Baidu Scholar) and other literature sources (e.g., Chinese Pharmacopoeia, 2015 edition, Chinese herbal classic books and PhD and MSc thesis, etc.). Results: Traditional uses were compiled in this review, including classic prescriptions and historical applications. Approximately 70 compounds, mainly including flavonoids, phenolics, lignans, limonoids and steroids, have been isolated and identified from P. orientalis. Among them, flavonoids were main components. Crude extracts and pure compounds isolated from P. orientalis exhibited various pharmacological activities, such as protection against ischemia and hypoxia-induced myocardial cells and hypoxia/reoxygenation cardiomyocyte, increase the blood flow in myocardium, expanding bronchus, anti-inflammatory and analgesic, and antithrombotic effects and so on. Conclusions: P. orientalis is a valuable source with therapeutic potential on a wide range of diseases especially cardiovascular-system disorders. Though most traditional uses of P. orientalis are supported by in vitro/vivo pharmacological studies, however, there is still a lack of researches on active pharmacodynamic ingredients as well as in-depth and in-vivo mechanistic studies. Therefore, isolation and identification of more active compounds (especially flavonoids), their structure-activity relationship and studies on pharmacodynamic mechanisms by more elaborative in-vivo studies on P. orientalis may be focused on in order to confirm efficacy of reported therapeutic effects of P. orientalis and help explore it's therapeutic potentials. Furthermore, research designs of pharmacological studies based on traditional uses of anti-rheumatoid arthritis through cell lines and animal models should also be considered as key research topics.