The hederagenin saponin SMG-1 is a natural FMLP receptor inhibitor that suppresses human neutrophil activation.
The pericarp of Sapindus mukorossi Gaertn is traditionally used as an expectorant in Japan, China, and Taiwan. Activated neutrophils produce high concentrations of the superoxide anion (O(2)(-)) and elastase known to be involved in airway mucus hypersecretion. In the present study, the anti-inflammatory functions of hederagenin 3-O-(3,4-O-di-acetyl-alpha-L-arabinopyranoside)-(1-->3)-alpha-l-rhamnopyranosyl-(1-->2)-alpha-l-arabinopyranoside (SMG-1), a saponin isolated from S. mukorossi, and its underlying mechanisms were investigated in human neutrophils. SMG-1 potently and concentration-dependently inhibited O(2)(*-) generation and elastase release in N-Formyl-Met-Leu-Phe (FMLP)-activated human neutrophils. Furthermore, SMG-1 reduced membrane-associated p47(phox) expression in FMLP-induced intact neutrophils, but did not alter subcellular NADPH oxidase activity in reconstituted systems. SMG-1 attenuated FMLP-induced increase of cytosolic calcium concentration and phosphorylation of p38 MAPK, ERK, JNK, and AKT. However, SMG-1 displayed no effect on cellular cAMP levels and activity of adenylate cyclase and phosphodiesterase. Significantly, receptor-binding analysis showed that SMG-1 inhibited FMLP binding to its receptor in a concentration-dependent manner. In contrast, neither phorbol myristate acetate-induced O(2)(*-) generation and MAPKs activation nor thapsigargin-caused calcium mobilization was altered by SMG-1. Taken together, our results demonstrate that SMG-1 is a natural inhibitor of the FMLP receptor, which may have the potential to be developed into a useful new therapeutic agent for treating neutrophilic inflammatory diseases.
Hwang
Tsong-Long
TL
Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan. htl@mail.cgu.edu.tw
Wang
Chien-Chiao
CC
Kuo
Yao-Haur
YH
Huang
Hui-Chi
HC
Wu
Yang-Chang
YC
Kuo
Liang-Mou
LM
Wu
Yi-Hsiu
YH
D002118:Calcium; D000242:Cyclic AMP; D016166:Free Radical Scavengers / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D018375:Neutrophil Activation / Q000187:drug effects*; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D010196:Pancreatic Elastase; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species; D044042:Receptors, Formyl Peptide / Q000037:antagonists & inhibitors*; D032127:Sapindus / Q000737:chemistry; D012503:Saponins / Q000737:chemistry* / Q000494:pharmacology*
D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D044042:Receptors, Formyl Peptide; D012503:Saponins; C552533:hederagenin 3-O-(3,4-O-diacetylarabinopyranoside)-1-3-rhamnopyranosyl-1-2-arabinopyranoside; D009828:Oleanolic Acid; D000242:Cyclic AMP; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D051057:Proto-Oncogene Proteins c-akt; D020929:Mitogen-Activated Protein Kinase Kinases; D010196:Pancreatic Elastase; C025763:hederagenin; D002118:Calcium