Nonenzymatic Stereoselective S-Glycosylation of Polypeptides and Proteins.

Here we report a nonenzymatic glycosylation reaction that builds axial S-glycosidic bonds under biorelevant conditions. This strategy is enabled by the design and use of allyl glycosyl sulfones as precursors to glycosyl radicals and exploits the exceptional functional group tolerance of radical processes. Our method introduces a variety of unprotected glycosyl units to the cysteine residues of peptides in a highly selective fashion. Through developing the second-generation protocol, we applied our method in the direct glycosylation of complex polypeptides and proteins. Computational studies were performed to elucidate the reaction mechanism.

Cobalt-Catalyzed Umpolung Alkylation of Imines To Generate α-Branched Aliphatic Amines.

Here we report a general and mild approach to prepare α-branched aliphatic amines from imines. This method capitalizes on a cobalt-catalyzed umpolung alkylation of imines, employs easily available reaction partners, and demonstrates a broad substrate scope. Mechanistic studies suggest this transformation occurs by a radical pathway.

Enantioselective Propargylation of Polyols and Desymmetrization of meso 1,2-Diols by Copper/Borinic Acid Dual Catalysis.

A copper/borinic acid dual catalytic reaction enabled the enantioselective propargylation of aliphatic polyols. Readily available reagents and catalysts were used in this transformation, which displayed good to excellent chemo- and stereoselectivity for a broad array of substrates. The method was also applicable to the desymmetrization of meso 1,2-diols to furnish products with three stereogenic centers and a terminal alkyne group in one operation.

Enhanced antitumor effect of curcumin liposomes with local hyperthermia in the LL/2 model.

Curcumin previously was proven to inhibit angiogenesis and display potent antitumor activity in vivo and in vitro. In the present study, we investigated whether a combination curcumin with hyperthermia would have a synergistic antitumor effect in the LL/2 model. The results indicated that combination therapy significantly inhibited cell proliferation of MS-1 and LL/2 in vitro. LL/2 experiment model also demonstrated that the combination therapy inhibited tumor growth and prolonged the life span in vivo. Furthermore, combination therapy reduced angiogenesis and increased tumor apoptosis. Our findings suggest that the combination therapy exerted synergistic antitumor effects, providing a new perspective fpr clinical tumor therapy.

[Analysis of effects of salt stress on absorption and accumulation of mineral elements in Elymus spp. using atomic absorption spectrophotometer].

Salinization contributes significantly to soil degradation and the growth and survival of plants. A high level of salts imposes both ionic and osmotic stresses on plants, resulting in an excessive accumulation of sodium (Na) in plant tissues. Na toxicity disrupts the uptake of soil nutrients. Plant uptake and absorption of macro-elements under salt stress have been studied in plants, but there is little literature addressing the effect of salt stress on plant accumulation and absorption of micro-elements. Species in Elymus genus are among the most important forage plants on high-salinity soils in China An experiment was conducted to study the effect of salt stress on accumulation and absorption of both macro- and micro-elements by wild plants of Elymus genus. Plant samples taken from two populations with different salt tolerance were tested and the level of 4 macro-elements, namely Na, K, Ca and Mg, and 4 micro-elements, namely Cu, Fe, Mn, Zn was determined using atomic absorption spectrophotometer. The relationship between the selection of elements in the process of absorption and accumulation and salt tolerance was also analyzed. The results showed that the level of Na in root and leaf tissues increased with increasing salt stress. The level of Na in leaf tissue of plants with high salt tolerance (HS) was significantly higher than that in plants with low salt tolerance (P<0.05). The level of K and Ca decreased in response to increasing salt stress, while that in HS was higher than in LS. The level of Fe and Zn in the tissues of both roots and leaves increased. No significant difference was detected between HS and LS samples in the level of Cu in root tissues, while that of Cu in leaf tissue of both samples increased. The level of Mn decreased with increasing salt stress, but was higher in HS than in LS. Fe and Zn in roots and leaves of HS were lower than in those of LS.