Mechanism of NKSE-5A and larixol inhibit fMLP-induced superoxide generation in human neutrophils

• Main Authors: Tzu Chi Tseng, 曾姿綺
• Other Authors: H. R. Liao
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/3n42tz

碩士 === 長庚大學 === 中醫學系天然藥物 === 104 === This study investigates the effect and the underlying mechanism of a lignin extracted from the Microtropis japonica, NKSE-5A and Larixol, a root extracted from Euphorbia formosana Hayata on N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) and phorbol 12-myristate 13-acetate (PMA)-induced respiratory burst in human neutrophils. Give a better understanding of inflammatory response with the regulation of neutrophils through different mechanism. Expectation of these natural products would be useful for therapy inflammatory diseases advance. This study was divided into two parts. The first part is NKSE-5A which was not found to be a toxic product. The results of anti-inflammatory activity showed that NKSE-5A had significant inhibitory activities on the release of superoxide anion in fMLP-induced neutrophils with IC50 values of 3.57±1.26 μM and 0.43±0.09 μM. NKSE-5A could not effect superoxide anion and other signal transduction which stimulated by PMA except for the phosphorylation of Akt. This study has shown that NKSE-5A had inhibitory effect on the phosphorylation of Akt induced by PMA but no effect on the fMLP-induced. NKSE-5A has been ruled out a free radical scavenger and it could not affect the activity of NADPH oxidase. In order to clarify NKSE-5A play an important anti-inflammatory role in signal transduction, our study has been evaluated the signal of PKC with NKSE-5A pretreated. The results demonstrated that NKSE-5A inhibited phosphorylation of PKC δ lead to block the activity of Akt. So that the PKC isoform have induced by PMA still can stimulate NAPDH oxidase to produce superoxide anion. The second part is Larixol which could not found to be a toxic product. Larixol inhibit the fMLP-induced superoxide anion and granules cathepsin G release in a concentration dependent manner with IC50 values of 1.94±0.25 μM and 4.17±0.58 μM. Larixol also suppresses fMLP-induced calcium influx. We conjecture that larixol target on the pathway of PLC via measuring intracellular cAMP level. But these results can not certainly indicate that larixol inhibits fMLP-induced superoxide production upstream of the NADPH oxidase. We have to confirm that larixol suppresses fMLP-induced superoxide anion production under these observations in our study. Thus, larixol possesses promising anti-inflammatory therapeutic potential.