Research On Effect Of White Tea On Cigarette Smoke-induced Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease（COPD）is caused by noxious particles or gases,the pathological features of COPD are persistent respiratory and airflow limitation.And cigarette smoking could increase the risk of COPD significantly.Most people believe that the main pathogenesis of COPD are inflammation,oxidative stress and protease overexpression.In current,more and more research focus on natural products for antioxidant and anti-inflammatory effect,which has the prevention and improvement of chronic diseases such as COPD.In this thesis,a mouse COPD model was established by smoking method,the pathological changes of lung tissue and the biochemical indicators of each sample were measured,and the effect and mechanism of white tea extract on improving COPD in mice were studied.The primary results are shown as following:1.The main chemical components and in vitro antioxidant activity of Baihao Yinzhen,Baipeony and Shoumei extracts from Fuding city were determined.The three white tea extracts contained high content of tea polyphenols,flavonoids,caffeine and amino acids,and showed strong antioxidant activity in vitro.The three grades of white tea extracts showed certain differences in antioxidation activity in vitro due to differences in the content and composition of active ingredients.Among them,YZ extract had the highest antioxidant activity,the IC₅₀for DPPH scavenging was only 14.15μg·ml^-1.2.The experiment shows that the three white tea extracts and EGCG could significantly improve the pathological damage of the alveolus,pulmonary interstitium and trachea of COPD mice,especially show high effect in inflammatory infiltration and emphysema;secondly,downregulate the levels of inflammatory factors IL-6 and TNF-αin the model group.The three kinds of white tea extracts have different effects on the improvement of lung tissue pathology and inflammation in COPD mice.MD and YZ extracts had the best effect.3.Within the safe dose range,white tea extract and EGCG treatments could significantly reduce the MDA content and MPO activity,upregulate SOD activity,regulate NO abnormality,and exhibit significant liver protection in COPD mice.The results suggested that the mechanism may be to upregulate the AMPK phosphorylation level.In summary,white tea extracts could obviously improve oxidative stress,inflammation response and regulate NO abnormalities in COPD mice.