Sabatier Phenomenon in Hydrogenation Reactions Induced by Single-Atom Density.

The Sabatier principle is a fundamental concept in heterogeneous catalysis that provides guidance for designing optimal catalysts with the highest activities. For the first time, we here report a new Sabatier phenomenon in hydrogenation reactions induced by single-atom density at the atomic scale. We produce a series of Ir single-atom catalysts (SACs) with a predominantly Ir1-P4 coordination structure with densities ranging from 0.1 to 1.7 atoms/nm2 through a P-coordination strategy. When used as the catalysts for hydrogenation, a volcano-type relationship between Ir single-atom density and hydrogenation activity emerges, with a summit at a moderate density of 0.7 atoms/nm2. Mechanistic studies show that the balance between adsorption and desorption strength of the activated H* on Ir single atoms is found to be a key factor for the Sabatier phenomenon. The transferred Bader charge on these Ir SACs is proposed as a descriptor to interpret the structure-activity relationship. In addition, the maximum activity and selectivity can be simultaneously achieved in chemoselective hydrogenation reactions with the optimized catalyst due to the uniform geometric and electronic structures of single sites in SACs. The present study reveals the Sabatier principle as an insightful guidance for the rational design of more efficient and practicable SACs for hydrogenation reactions.

Synergistic Neuroprotective Effects of Two Herbal Ingredients via CREB-Dependent Pathway.

As two natural oligosaccharide esters, 3,6'-Disinapoyl sucrose (DISS) and tenuifolisideA (TFSA) are originating from the root of Polygala tenuifolia Willd, a traditional Chinese medicine used in treatment of mental disorders. Previous reports have shown that both of them possess in vitro neuroprotective effects by stimulating different upstream pathways related with cyclic AMP-responsive element-binding protein (CREB). In the present study, we investigated the additive neuroprotective effects of DISS and TFSA on Glu-induced damage of SY5Y cells and purposed the possible underlying mechanism. The interaction between DISS and TFSA showed a clear-cut synergistic effect as evidenced by combination index (CI). Additional evidence from biochemical (NOS activity) assays confirmed their additive inhibition on the Glu-induced NOS hyperactivation. Moreover, we showed that co-treatment of DISS and TFSA resulted in an additively up-regulated phosphorylation of CREB as well as increased expressions of CRTC1 and BDNF. Neuroprotective effects of DISS and TFSA on Glu-induced decrease in cell viability were blocked by MAPK/ERK1/2 inhibitor (U0126) and PI3-K inhibitor (LY290042). Nevertheless, the CRTC1 or BDNF expression induced by these two compounds was significantly reduced in the presence of either ERK or PI3-K inhibitor, indicating that the two oligosaccharide esters shared some common pathways in the regulation of CREB-BDNF pathway. Taken together, we, for the first time, showed that DISS and TFSA exerted the additive neuroprotective effects on CREB-BDNF signaling pathway through complementary mechanisms.

[Anti-radiation effect and mechanism studies of ethanol extracts from Spatholobus suberectus and its active component catechin].

To study the anti-radiation effect and mechanism of ethanol extracts from Spatholobus suberectus and its active component catechin, ICR mice were exposed to 6Gy irradiation and randomly divided into normal group, model group, positive control group (amifostine, 43.6 mg•kg⁻¹, iv 30 min before irradiation), SSD group (10, 20, 40 g•kg⁻¹) and catechin group (50, 100, 200 mg•kg⁻¹). The mice were administered the appropriate drugs once a day after irradiation for 28 consecutive days. Blood samples were collected from the tail end and the number of peripheral blood cells was counted before irradiation and on day 1, 3, 7, 14, 21 and 28 using a microcell counter. Changes of thymus and spleen index of mice on day 7 were observed. The serum SOD, GSH-Px activity and MDA level were detected by the colorimetric method. The colony forming ability of bone marrow hematopoietic progenitor cells on day 7 was detected by semi solid culture method. The HE staining was adopted to observe the pathological changes. The apoptosis of bone marrow cells was detected by flow cytometry. The expression of cleaved caspase-3 and Bax of bone marrow cells were measured separately by western-blotting and immunohistochemistry method. SSD and catechin can both significantly revert the irradiated-induced decline in hematological parameters (RBC, WBC, PLT, Hb), improve thymus and spleen index, significantly enhance serum SOD and GSH-Px activity and decrease the MDA level. The proliferation and differentiation of hematopoietic progenitor cells in bone marrow were promoted, the apoptosis of bone marrow cells was significantly up-regulated and the expression of cleaved caspase-3 and Bax was significantly reduced in SSD and catechin group. SSD and catechin have significant anti-radiation effect and its mechanism may be related to hematopoietic promoting, antioxidant and anti-apoptotic effects.

[Effect of six class of Kaixin San formulas on pharmacological and preliminary mechanism of Alzheimer's disease mice].

The efficacy of Chinese herbal formulas in treating Alzheimer has been proved in many studies. In this study, six different Kaixin San formulas were compared to investigate their effects on learning and memory decline, brain-derived neurotrophic factor (BDNF) in the hippocampus, tau protein, acetylcholinesterase (AChE) and N-terminal pro-brain natriuretic peptide (NT-proBNP). Kunming mice were selected and established a mouse model of Alzheimer's by intraperitoneal injection of D-galactose and sodium nitrite, continued intragastric 4 weeks, using the ability of learning and memory in Morris water maze test to evaluate the animals in each group; the content of BDNF in the hippocampus of mice with Western blotting detected; ELISA method for the detection of each group of mice hippocampal tau protein,p-Tau protein, Aß,Ach,AchE and serum NT-proBNP levels. The results showed that, Kaixin San of Qianjin Yaofang three dose recorded significantly improved learning and memory ability of mice; increased the content of BDNF and Ach in the hippocampus; decreased the content of Aß, Tau protein, p-Tau protein in the hippocampus; high, middle dose significantly decreased the serum NT-proBNP and AchE in hippocampus, the effect is most significant. Part dose of Kaixin San of Yixin Fang, Kaixin Wan of Yimen Fang, Dingzhi Xiaowan of Beji Qianjin Yaofang and Dingzhi Wan of Guji Luyan could improve the learning and memory ability evaluation indicators, significantly increased BDNF and Ach in the hippocampus of AD model mice, reduced the Aß, Tau protein, p-Tau protein in hippocampus of AD model mice, decreased the NT-proBNP and AchE in serum of AD mice, the effect is more significant. Three does of Buxin Tang of Qianjin Yi had no effects of treatment in Alzheimer's disease. The results showed the treatment in AD of Kaixin San of Qianjin Yaofang is the most significant.