Study on lignans in silver chrysanthemum
Parthenium phytophorus Linn. belongs to the Asteraceae family and is an annual herbaceous plant mainly distributed in northeastern Guangdong (Dapu, Meixian) and southwestern Guangdong (Leizhou Peninsula), western Guangxi (Longlin), southwestern Guizhou (Xingyi), and southern Yunnan (Hekou). Silver chrysanthemum is mainly used in folk medicine to treat allergies, ulcers, anemia, fever, facial neuralgia, and skin diseases. Modern pharmacological studies have shown that silver chrysanthemum has anti-inflammatory, antibacterial, anti HIV, anti-tumor, and hypoglycemic activities. Chemical composition research reports that it mainly contains sesquiterpenes, monoterpenes, triterpenes, flavonoids, and phenolic acids. In recent years, the anti-inflammatory activity of silver chrysanthemum has received widespread attention. Therefore, in order to clarify its anti-inflammatory pharmacological substance basis, this paper studied the chemical composition of the ethyl acetate extract of the 95% ethanol extract of silver chrysanthemum, and tested the anti neuroinflammatory activity of the isolated compounds, in order to discover compounds with significant anti neuroinflammatory activity and provide a basis for the subsequent chemical composition and pharmacological activity research of silver chrysanthemum.

This study investigated the lignans in the ethyl acetate fraction of the above ground parts of silver chrysanthemum, and isolated five lignans, including one new 8-O-4 ‘- oxo lignan, three bicyclic lignans, and one biphenyl cyclooctene lignan. The anti neuroinflammatory activity of the above 5 compounds was screened, and it was found that compound 1 exhibited moderate NO inhibitory activity, while the other compounds had no inhibitory effect on NO release. The MTT assay results showed that lignans did not have cytotoxic effects at the tested concentration and did not affect the survival rate of BV-2 microglia. Based on the above research results, it is speculated that lignans may not be the main pharmacological substance basis for the anti-inflammatory activity of silver chrysanthemum. Based on literature reports, we found that the anti-inflammatory active ingredients of silver chrysanthemum mainly focus on sesquiterpene lactones. In order to further explore the material basis of its anti neuroinflammatory activity, we will continue to study its chemical composition and focus on sesquiterpene components, in order to obtain compounds with good anti neuroinflammatory activity. In addition, literature review found that there are few reports on the chemical composition of lignans in silver chrysanthemum. This study enriches the structural types of the chemical composition of silver chrysanthemum and provides a basis for subsequent research.