Anti-PAK1/2/3 (E417) Antibody (A25595)

Ruscogenin, a natural steroidal sapogenin, presents in both food and medicinal plants. It has been found to exert significant anti-inflammatory activities. Considering that activation of neutrophil is a key feature of inflammatory diseases, this study was performed to investigate the inhibitory effect of ruscogenin and its underlying mechanisms responsible for neutrophil activation. Ruscogenin displayed potent antioxidative effects against Formyl-Met-Leu-Phe (FMLP)-induced extra- and intracellular superoxide generation in mouse bone marrow neutrophils, with IC50 values of 1.07±0.32 μM and 1.77±0.46 μM, respectively. Phorbol myristate acetate (PMA)-elicited extra- and intracellular superoxide generation were also suppressed by ruscogenin, with IC50 values of 1.56±0.46 μM and 1.29±0.49 μM, respectively. However, ruscogenin showed weak inhibition in NaF-induced response. Inhibition of superoxide generation was mediated neither by a superoxide-scavenging ability nor by a cytotoxic effect. Furthermore, ruscogenin inhibited the membrane translocation of p47phox and p67phox. It reduced FMLP-induced phosphorylation of cytosolic phospholipase A2 (cPLA2) and p21-activated kinase (PAK). The cellular cyclic adenosine monophosphate (cAMP) levels and protein kinase A (PKA) expression were increased by ruscogenin. Moreover, ruscogenin inhibited phosphorylation of protein kinase B (Akt), p38 mitogen-activated protein kinase (p38MAPK), extracellular signal-regulated kinase 1 and 2 (ERK1/2), and c-Jun N-terminal kinase (JNK). In addition, the inhibitory effects of ruscogenin on superoxide production and the phosphorylation of Akt, p38MAPK, and ERK1/2 were reversed by PKA inhibitor (H89), suggesting a PKA-dependent mechanism. In summary, our data suggest that ruscogenin inhibits activation of neutrophil through cPLA2, PAK, Akt, MAPKs, cAMP, and PKA signaling pathways. Increased PKA activity is associated with suppression of the phosphorylation of Akt, p38MAPK, and ERK1/2 pathways.

Diosgenin possesses anti-inflammatory and anticancer properties. Activated neutrophils produce high concentrations of the superoxide anion which is involved in the pathophysiology of inflammation-related diseases and cancer. In the present study, the inhibitory effect and possible mechanisms of diosgenin on superoxide generation were investigated in mouse bone marrow neutrophils. Diosgenin potently and concentration-dependently inhibited the extracellular and intracellular superoxide anion generation in Formyl-Met-Leu-Phe (FMLP)- activated neutrophils, with IC50 values of 0.50 ± 0.08 μM and 0.66 ± 0.13 μM, respectively. Such inhibition was not mediated by scavenging the superoxide anion or by a cytotoxic effect. Diosgenin inhibited the phosphorylation of p47phox and membrane translocation of p47phox and p67phox, and thus blocking the assembly of nicotinamide adenine dinucleotide phosphate oxidase. Moreover, cellular cyclic adenosine monophosphate (cAMP) levels and protein kinase A (PKA) expression were also effectively increased by diosgenin. It attenuated FMLP-induced increase of phosphorylation of cytosolic phospholipase A (cPLA2), p21-activated kinase (PAK), Akt, p38 mitogen-activated protein kinase (p38MAPK), extracellular signal-regulated kinase (ERK1/2), and c-Jun N-terminal kinase (JNK). Our data indicate that diosgenin exhibits inhibitory effects on superoxide anion production through the blockade of cAMP, PKA, cPLA2, PAK, Akt and MAPKs signaling pathways. The results may explain the clinical implications of diosgenin in the treatment of inflammation-related disorders.