Structural Characterization of Polysaccharides of a Productive Strain of the Culinary-Medicinal King Oyster Mushroom, Pleurotus eryngii (Agaricomycetes), from Italy

A preliminary biological investigation of the dry basidiomata of strain C-142-c of Pleurotus eryngii has shown significant antioxidant activity. Two different polysaccharides (PEPS-A1 and PEPS-A2) were isolated from the cultivated edible mushroom, P. eryngii C-142-c strain. Based on acid hydrolysis, methylation analysis, and nuclear magnetic resonance experiments (1H, 13C, distortionless enhancement by polarization transfer, double quantum filtered correlation spectroscopy, total correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear singlequantum correlation spectroscopy, and heteronuclear multiple-bond correlation spectroscopy), the structures of the repeating unit of PEPS-A1 and PEPS-A2 were established as follows: (1) PEPS-A1 (a-glucan): [\u21926)-a-D-Glcp-(1\u21926)- a-D-Glcp-(1\u2192]n; and (2) PEPS-A2 (b-glucan): [\u21926)-b-D-Glcp-(1\u21926)-b-D-Glcp-(1\u2192]n. The antioxidant activity of PEPS-A1 and PEPS-A2 was evaluated as hydroxyl radical scavenging activity. PEPS-A1 and PEPS-A2 showed SC50 values of 400 \ub5g/mL and 122 \ub5g/mL, respectively, suggesting their possible use as a dietary supplement in functional foods. The polysaccharides were tested for their activity on cell viability using a colorectal adenocarcinoma cell line (HT29). Both polysaccharides affected cell viability after 48 and 72 hours of treatment, inducing the death of 50% of HT-29 cells between 0.25 and 1 \ub5g/mL and between 0.5 and 1 \ub5g/mL, respectively, for PEPS-A1 and PEPS-A2. These results are promising for future applications of these mushroom-derived polysaccharides as antioxidants and antitumor agents

Application of Chiral Amine-Imine Ligands in Palladium-Catalyzed Polyketone Synthesis: Effect of Ligand Backbone on the Polymer Stereochemistry

Two pairs of enantiomerically pure chiral bidentate nitrogen-donor ligands (N*-N) featuring one sp3 and one sp2 nitrogen atom have been applied to the CO/vinyl arene copolymerization reaction catalyzed by the corresponding monocationic palladium(II) complexes [Pd(CH3)(CH3CN)-(N*-N)][PF6]. The ligand fragment containing the sp2 nitrogen atom is a 2-pyridinyl or an 8-quinolinyl building block, while the chiral framework of the ligand derives from (S)-(+)-2,2\u2019 -(2-azapropane-1,3-diyl)-1,1\u2019-binaphthalene or from trans-2,5-dimethylpyrrolidinyl. Ligands with the binaphthyl moiety generate catalysts showing a moderate activity, while ligands having the pyrrolidinyl fragment result in very low activity species. The stereochemistry of the synthesized polyketones depends on the sp2 nitrogen-containing fragment: ligands with the 2-pyridinyl group lead to atactic copolymers, whereas those with the quinolinyl moiety give an isotactic polyketone. The effect of the nature of the quinone, added to the reaction mixture as oxidant, has been investigated. MALDI-TOF analysis reveals the formation of several polymeric chains, differing in the presence of various end-groups

Application of Chiral Amine-Imine Ligands in Palladium-Catalyzed Polyketone Synthesis: Effect of Ligand Backbone on the Polymer Stereochemistry

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