The phytochemistry, pharmacology, pharmacokinetics, quality control, and toxicity of Forsythiae Fructus: An updated systematic review

Forsythiae Fructus (FF), the dried fruit of F. suspensa, is commonly used to treat fever, inflammation, etc in China or other Asian countries. FF is usually used as the core herb in traditional Chinese medicine preparations for the treatment of influenza, such as Shuang-huang-lian oral liquid and Yin-qiao powder, etc. Since the wide application and core role of FF, its research progress was summarized in terms of traditional uses, phytochemistry, pharmacology, pharmacokinetics, quality control, and toxicity. Meanwhile, the anti-influenza substances and mechanism of FF were emphasized. Till now, a total of 290 chemical components are identified in F. suspensa, and among them, 248 components were isolated and identified from FF, including 42 phenylethanoid glycosides, 48 lignans, 59 terpenoids, 14 flavonoids, 3 steroids, 24 cyclohexyl ethanol derivatives, 14 alkaloids, 26 organic acids, and 18 other types. FF and their pure compounds have the pharmacological activities of anti-virus, anti-inflammation, anti-oxidant, anti-bacteria, anti-tumor, neuroprotection, hepatoprotection, etc. Inhibition of TLR7, RIG-I, MAVS, NF-κB, MyD88 signaling pathway were the reported anti-influenza mechanisms of FF and phenylethanoid glycosides and lignans are the main active groups. However, the bioavailability of phenylethanoid glycosides and lignans of FF in vivo was low, which needed to be improved. Simultaneously, the un-elucidated compounds and anti-influenza substances of FF strongly needed to be explored. The current quality control of FF was only about forsythoside A and phillyrin, more active components should be taken into consideration. Moreover, there are no reports of toxicity of FF yet, but the toxicity of FF should be not neglected in clinical applications.