The hederagenin saponin SMG-1 is a natural FMLP receptor inhibitor that suppresses human neutrophil activation |
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Authors: | Tsong-Long Hwang Chien-Chiao Wang Hui-Chi Huang Liang-Mou Kuo |
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Institution: | a Graduate Institute of Natural Products, Chang Gung University, Taoyuan 333, Taiwan b Division of Herbal Drugs and Natural Products, National Research Institute of Chinese Medicine, Taipei 112, Taiwan c School of Chinese Medicine Resources, China Medical University, Taichung 404, Taiwan d Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 807, Taiwan e Department of General Surgery, Chang Gung Memorial Hospital at Chia-Yi, Taiwan |
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Abstract: | 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 (O2 −) 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-α-l-arabinopyranoside)-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-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 O2 − generation and elastase release in N-Formyl-Met-Leu-Phe (FMLP)-activated human neutrophils. Furthermore, SMG-1 reduced membrane-associated p47phox 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 O2 − 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. |
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Keywords: | AC adenylyl cyclase Akt protein kinase B ARDS acute respiratory distress syndrome BAPTA-AM 1 2-bis(2-aminophenoxy)ethane-N N N&prime N&prime -tetraacetic acid tetrakis(acetoxymethyl ester) cAMP cyclic adenosine 3&prime 5&prime -monophosphate CB cytochalasin B COPD chronic obstructive pulmonary disease ERK extracellular regulated kinase FMLP N-Formyl-Met-Leu-Phe GPCR G protein-coupled receptor H89 N-(2-((p-bromocinnamyl)amino)ethyl)-5-isoquinolinesulfonamide IBMX 3-isobutyl-1-methylxanthine JNK c-Jun N-terminal kinase LDH lactate dehydrogenase MAPK mitogen-activated protein kinase O2 els-cdn &minus" target="_blank">com/sd/entities/rad" class="glyphImg">&minus superoxide anion PDE phosphodiesterase PKA protein kinase A PKC protein kinase C PMA phorbol myristate acetate Ro318220 3-(1-(3-(amidinothio)propyl-1H-indol-3-yl))-3-(1-methyl-1H-indol-3-yl)maleimide ROS reactive oxygen species SOD superoxide dismutase WST-1 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2 4-disulfophenyl)-2H-tetrazolium monosodium salt |
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