The pharmacological properties of chrysophanol, the recent advances.

As a universal Chinese medicine, Rhei Radix et Rhizoma was used for centuries in different fields including pharmaceutical, health care and cosmetics. Chrysophanol (Chr) is one of the most important anthraquinone components isolated from plants of the Rheum genus. Current reports show that in Rheum officinale, Chr is the most abundant free anthraquinone compound [1] and exerts a number of beneficial effects, such as anti-inflammation, anti-cancer, and anti-depressive effects and offers neuroprotection. We collected information about Chr from the Internet databases PubMed, Web of Science, Europe PMC and CNKI with a combination of keywords including "Chr", "Pharmacology", and "Pharmacokinetics". All data about this ingredient in this review were extracted from articles published before September 2019. Based on the literature found, we concluded that (1) Chr exhibited potential anti-inflammation, anti-cardiovascular disease (CVD)and anti-cancer activities by regulating signaling pathway transduction (NF-κB, MAPK, PI3K/Akt, etc.); (2) compared with free Chr, pharmacokinetic studies revealed that other forms of Chr, such as nanoparticle-based and liposome-based Chr, showed high bioavailability. Nevertheless, we also found that the understanding of the exact differences in the regulation of multiple molecular signaling pathways is in a preliminary stage and needs to be clarified. Moreover, further studies are required to determine the apoptotic mechanism of Chr in cancer cells. Finally, we found that (3) structure modification studies demonstrated potential relationships between structure and drug activity. The purpose of this review is to summarize the pharmacological activities, intracorporal processes and structure-activity relationships of Chr and to provide an up-to-date reference for further research and clinical applications.