Antioxidant Effects And Mechanism Of Taraxacum Mongolicum Flavonoids On Cigarette Smoke-induced Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease(COPD)is the third fatal disease in the world,characterized with persistent,incomplete reversible and progressive aggravated airflow limitation.Cigarette smoke and harmful particles have been considered as important factors causing chronic inflammation and oxidative stress reaction.Since currently,there is no effective treatment for COPD because of its unclear pathogenesis,more attention should be paid on development of effective new drugs with multi-targets and multi-pathways.As a medicine and food homologous Chinese herbal medicine,taraxacum mongolicum is rich in flavonoids,sesquiterpenoids,phenolic acids and other chemical components with anti-inflammatory and anti-oxidation biological activity.Thus,the purpose of this study was to investigate the antioxidative effects of total flavonoids of taraxacum mongolicum on cigarette smoke-induced chronic obstructive pulmonary diseases.Methods: The free radical scavenging capacity of total flavonoids in stem leaf and root of taraxacum mongolicum was detected by DPPH and ABTS free radical scavenging experiments.Six groups were divided in this study,normal control group(CON),cigarette extract group(CSE),low-dose total flavonoids in root of taraxacum mongolicum group(Root-LD),high-dose total flavonoids in root of taraxacum mongolicum group(Root-HD),low-dose total flavonoids in stem leaf of taraxacum mongolicum group(Leaf-LD)and high-dose total flavonoids in stem leaf of taraxacum mongolicum group(Leaf-HD).In vitro,COPD model was established by CSE stimulation on human lung cancer epithelial cell line A549 and MTT assay was investigated for cell viability.Oxidative factors LDH,MDA,GSH,SOD and oxygen free radicals(ROS)were assessed and Nrf2 signaling pathway was detected by RT-PCR and western blot in each group.And in vivo murine COPD model was established via 12-week cigarette smoke exposure.Lung function was detected and parameters including airway resistance(Raw),dynamic lung compliance(Cdyn)and Forced Expiratory Volume in 100ms(FEV0.1)were tested.Mice lung tissues were collected to detect the levels of oxidative factors MDA,GSH and SOD.RT-PCR was applied to detect the activation of Nrf2 signaling pathway.HE stainning and immunohistochemistry were used to determine the expression of 8-OHd G and other related proteins through Nrf2 signaling pathway.Results: 1.In total flavonoids in stem leaf and root of taraxacum mongolicum,the EC50 values of DPPH free radicals scavenging radical rates were 54.88 μg/m L and 123.50 μg/m L,respectively.EC50 values of ABTS radical scavenging rates were 229.41 μg/m L and 559.07 μg/m L,respectively.2.The proper concentration of CSE on cell was 10%~30%.3.Total flavonoids of taraxacum mongolicum could help to inhibit the generation of ROS and LDH in CSE induced A549 cells.4.In vitro and in vivo,total flavonoids of taraxacum mongolicum could help to downregulate oxidative factors ROS,LDH,MDA and 8-OHd G respectively and upregulate levels of antioxidant factors GSH and SOD,especially in Leaf-LD and Leaf-HD groups.5.Pulmonary HE stainning showed an inhibition of total flavonoids of taraxacum mongolicum on CSE-induced inflammatory response in the COPD model,with a significant effect in Leaf-LD and Leaf-HD groups.6.Lung function test exhibited that total flavonoids of taraxacum mongolicum could help improve Cdyn and FEV0.1 in mice and reduced Raw,especially in Leaf-LD and Leaf-HD groups.7.Total flavonoids of taraxacum mongolicum showed an antioxidative ability both in vitro and in vivo,possibly through up-regulating the m RNA levels and protein expression of Nrf2,SOD1,and HO1.Data showed significant difference in LeafLD and Leaf-HD groups.Conclusions: Above all,our study has investigated the antioxidative effects of total flavonoids in stem leaf and root of taraxacum mongolicum on cigarette smoke-induced chronic obstructive pulmonary diseases.The total flavonoids could upregulate Nrf2,SOD1 and HO1 and enhance the expression of antioxidant factors,which thereby inhibited the production of ROS and other oxidants,weakened the oxidative damage and inflammation of the lungs and improved lung function.These might help to provide an experimental basis for the further clinical screening of new and effective drugs on COPD prevention and treatment.