Chemical component and in vitro protective effects of Matricaria chamomilla (L.) against lipopolysaccharide insult

Ethnopharmacological relevance:Chamomile (Matricaria chamomilla L.) is a popular herbal tea for the treatment of hepatitis and cholecystitis in traditional Uygur medicines.

Aim of the study:To investigate the anti-inflammatory activity and chemical composition of M. chamomilla, and clarify its molecular mechanism.

Materials and methods:M. chamomilla was extracted with 75% ethanol and then extracted with different solvents to obtain five fractions, namely petroleum ether fraction (EOPE), dichloromethane fraction (EOD), ethyl acetate fraction (EOEA), n-butanol fraction (EOB), and water fraction (EOW). Cytotoxicity and the effect on the nitric oxide (NO) production of RAW264.7 cells induced by LPS of the five fractions were screened, and the most active one (EOD) was selected for further investigations. The components of EOD were identified by LC-MS/MS analysis in combination with comparison of retention time and UV absorption with authentic compounds by HPLC. In addition, five most abundant compounds of EOD were isolation by column chromatography and semi-preparative HPLC and their structures were further confirmed by HRMS and NMR data analysis and comparison with data in literatures. Then the underlying anti-inflammatory mechanism of EOD were predicted through Network pharmacology using the identified compounds from EOD, and further verified by Western Blot and ELISA experiments.

Results:EOD showed the most significant inhibition ratio against NO in RAW264.7 cells without toxicity among the tested five fractions. Thirty-seven compounds including flavonoid-O-glycoside, flavonoid aglycone, methylated flavonoid aglycone, phenolic acid, coumarin, sesquiterpene, and triterpene were identified from EOD by LC-MS/MS and comparison with authentic compounds. The five most abundant compounds in EOD were isolated and determined to be axillarin (26), tricin (30), chrysoeriol (31), centaureidin (33) and chrysosplenetin (35). IL-6, NF-κB, ERK1 and ERK2 cascade, TNF were the most important anti-inflammatory targets of EOD predicted by Network pharmacology. Western Blot and ELISA experiments revealed that EOD significantly decreased the protein expression levels of inflammatory factors (PGE₂, MCP-1, IL-6, TNF-α), iNOS, COX-2, NF-κB (p-P65 and p-IκBα), MAPKs (p-p38, p-ERK and p-JNK), and increased the protein expression levels of Nrf2, HO-1 and CYP2E1. In addition, EOD blocked the p65 protein into the nucleus and promoted the nuclear translocation of Nrf2 in RAW264.7 cells induced by LPS.

Conclusion:M. chamomilla exerted anti-inflammatory effect via NF-κB, MAPK and Nrf2/HO-1 pathways. It could be further applied as a safe anti-inflammatory agent from natural source.

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