Saponins from Panax japonicus attenuate age-related neuroinflammation via regulation of the mitogen-activated protein kinase and nuclear factor kappa B signaling pathways

Neuroinflammation is recognized as an important pathogenic factor for aging and related cognitive disorders. Mitogen-activated protein kinase and nuclear factor kappa B signaling pathways may mediate neuroinflammation. Saponins from Panax japonicus are the most abundant and bioactive members in rhizomes of Panaxjaponicus, and show anti-inflammatory activity. However, it is not known whether saponin from Panaxjaponicus has an anti-inflammatory effect in the aging brain, and likewise its underlying mechanisms. Sprague-Dawley rats were divided into control groups （3-, 9-, 15-, and 24-month-old groups） and saponins from Panaxjaponicus-treated groups. Saponins from Panaxjaponicus-treated groups were orally administrated saponins from Panaxjaponicus at three doses of 10, 30, and 60 mg/kg once daily for 6 months until the rats were 24 months old. Immunohistochemical staining and western blot assay results demonstrated that many microglia were activated in 24-month-old rats compared with 3- and 9-month-old rats. Expression of interleukin-1β, tumor necrosis factor-a, cyclooxygenase-2, and inducible nitric oxide synthase increased. Each dose of saponins from Panaxjaponicus visibly suppressed microglial activation in the aging rat brain, and inhibited expression levels of the above factors. Each dose of saponins from Panax japonicus markedly diminished levels of nuclear factor kappa B, IKBa, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38. These results confirm that saponins from Panaxjaponicus can mitigate neuroinflammation in the aging rat brain by inhibition of the mito- gen-activated protein kinase and nuclear factor kappa B signaling pathways.

Accelerated oxygen evolution kinetics on Ir-doped SrTiO_(3) perovskite by NH_(3) plasma treatment

Exploring low-cost and high-performance catalysts for oxygen evolution reaction(OER)remains to be a great challenge.Iridium-based perovskite oxide has large potential in OER because of its intrinsic activity and outstanding physicochemical properties.In this study,iridium-doped strontium titanate(Ir-STO)solution is brushed on a Ti sheet by the traditional method to obtain the Ir-STO/Ti electrodes after being calcined at a high temperature.The microstructure and electrocatalysis properties of the Ir-STO are further modified by a facile and scalable NH_(3)-plasma strategy.In addition to the doping of Ir,the NH_(3) plasma treatment further results in N-doping into Ir-STO,which enriches active species and causes oxygen vacancies near doped sites.The resulting N,Ir-STO/Ti electrode reveals excellent acidic OER activity with the lowest overpotential of 390 m V at 10 m A/cm^(2) and the smallest Tafel slope of 140 mV/dec after 10-min plasma treatment.Therefore,the great potential of activated N,Ir-STO/Ti is regarded as a catalyst for the OER,and thus making a new opportunity for developing other perovskite catalysts via NH_(3) plasma treatment.