DFT investigation of the DDQ-catalytic mechanism for constructing C-O bonds.

In this study, we investigated the photo-catalytic mechanisms for the construction of C-O bonds from arenes (benzene, 2',6'-dimethyl-[1,1'-biphenyl]-2-carboxylic acid, or 2,4-dichloro-1-fluorobenzene), catalyzed by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). All the structures for the Gibbs free surfaces were calculated at the M06-2X-D3/ma-def2-SVP level in the SMD solvent model. Also, TDDFT calculations of DDQ were performed at the PBE1PBE-D3/ma-def2-SVP level in the SMD solvent model. The computational results indicated that DDQ, serving as a photo-catalyst, would be excited under visible light of 450 nm, aligning well with experimental observations as reflected in the UV-vis spectrum. Gibbs free energy surface analyses of the three reactions suggested that the path involving 3DDQ* activating the reactant (-COOH, H2O, or CH3OH) is favorable. Additionally, the role of O2 was investigated, revealing that it could facilitate the recycling of DDQ by lowering the energy barrier for the conversion of the DDQH˙ radical (not DDQH2) into DDQ. The use of ρhole and ρele can reveal the photo-catalytic reaction and charge transfer processes, while localized orbital locator isosurfaces and electron spin density isosurface graphs were employed to analyze structures and elucidate the single electron distribution. These computational results offer valuable insights into the studied interactions and related processes, shedding light on the mechanisms governing C-O bond formation from arenes catalyzed by DDQ.

[Effect of NaCl stress on physiological characteristics of Physalis alkekengi var. franchetii test-tube plantlet].

OBJECTIVE: To investigate the effect of NaCl stress on the growth and physiological characteristics of Physalis alkekengi var. franchetii, and to discuss the mechanism of salt tolerance. METHODS: The test-tube plantlet was cultured on the stress medium with NaCl (0.2%~1.0%), the content of proline, soluble sugar, soluble protein, chlorophyll and malondialdthyde (MDA), and membrane relative permeability, as well as the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were determined and analyzed. RESULTS: The average height, stem diameter, root length, number of root and chlorophyll content gradually decreased at salinity less than or equal 0.6% NaCl, then decreased rapidly at salinity greater than or equal 0.8% NaCl, while the root formation was significantly inhibited. The content of free proline and SOD activities always increased with NaCl concentration increasing (0.2%~ 1.0%). Nevertheless, the contents of soluble sugar, soluble protein and the activities of CAT and POD increased firstly and then decreased, but the contents of soluble sugar and soluble protein were higher than those of the control group, whereas the content of MDA and membrane relative permeability accumulated slowly at salinity less than or equal 0.6% NaCl, then increased rapidly at salinity greater than 0.8% NaCl. CONCLUSION: The test-tube plantlet has an adaptability to salty environment at salinity less than or equal 0.6% NaCl, and the test-tube plantlet can alleviate the salty injury by increasing the contents of osmotic regulation substances, such as soluble sugar and soluble protein, decreasing the osmotic potential, and increasing the activities of antioxidant enzymes.

[Study on the optimum combinations of plant hormone in callus culture of Thermopsis lanceolata].

OBJECTIVE: To explore the effects of different hormone combinations on callus induction of Thermopsis lanceolata. METHODS: The effects of different hormone concentrations and ratio on callus induction and subculture multiplication of Thermopsis lanceolata were investigated by orthogonal design methods. RESULTS: The optimal medium of callus induction for hypocotyls explants was MS + 2, 4-D (0.5 mg/L) + BA (1.0 mg/L) + NAA (1.0 mg/L) + IAA (0.5 mg/L). The best medium of callus subculture multiplication for hypocotyl explants was MS with 2,4-D (0.1 mg/L) + BA (0.1 mg/L) + NAA (0.2 mg/L) + IAA (0.5 mg/L) . In the process of callus subculture multiplication, the effect extent of four kinds of hormones for hypocotyl explants was BA > 2,4-D > IAA > NAA. The growth curve of callus culture optimal hormone combination was "S" curve. CONCLUSION: The rapid callus culture system for Thermopsis lanceolata is established for the first time. It provides a new way for protecting and utilizing Thermopsis lanceolata species resources through the modern biotechnology.

[Effects of different salt-alkaline stress on seed germination and seedling physiological characteristics of Codonopsis pilosula].

OBJECTIVE: To improve salt resistance of Codonopsis pilosula seeds and seedlings under different salt-alkaline stress, the seed germination and physiological characteristics of seedlings were studied. METHODS: Several physiological indexes of Codonopsis pilosula under different salt-alkaline stress were measured, such as the germination vigor, germination rate, relative germination rate and recovery germination rate,as well as others indexes like the contents of chlorophyll, soluble protein, water and MDA and the activities of POD and SOD. RESULTS: The inhibitory effects of three salts on seed germination were Na2 CO3 > NaCl + Na2 CO3 > NaCl with an increased salt concentration. The contents of chlorophyll, soluble protein and water were found significant different (P < 0.05) from the negative control group, along with the decreased of these indexes. However, positive correlation existed between MDA content and salt treatment concentration. In addition, the change trend of SOD and POD activity were similar. They were increased firstly, and then decreased as the stress intensity extended. CONCLUSION: The seeds and seedlings under different salt-alkaline stress were inhibited, with different inhibitory extent as Na2CO3 > NaCl + Na2 CO3 > NaCl.

[Specific anti-tumor effect of immune competent cell induced by HSP-70 of HeLa cells in vitro].

BACKGROUND & OBJECTIVE: Recent studies indicated that heat shock proteins (HSPs) are associated with antigenic peptides and participate in the antitumor T cell response in animals. This study was designed to investigate the mechanism of anti-tumor effect of immune competent cells (ICC) induced by HSP-70 of HeLa (cervical carcinoma) cells in vitro. METHODS: The normal peripheral blood mononuclear cells(PBMCs) stimulated with HSP-70 of HeLa cells in vitro. T cell phenotypes were analyzed before and after stimulated by PBMCs. HSP-70 primed the immune competent cells (ICCs) from PBMCs were tested for cytotoxic activity against HeLa cell. RESULTS: CD3+ cell was 85.73 +/- 1.44%, up from 57.68 +/- 1.46% before the amplification(P < 0.002). CD8+ cell was 48.06 +/- 1.66%, up from 23.56 +/- 1.86% before the amplification(P < 0.002). The ICCs induced by HSP-70 were shown significant cytotoxic activity (82.69 +/- 1.97%, 62.11 +/- 1.61%) against HeLa cells and cervical carcinoma cells, and the cytotoxic activity (31.05 +/- 2.09%) of the ICC against HeLa cells could be blocked by anti-HSP-70 antibody. CONCLUSION: The ICC can be induced selectively by PBMCs with HSP-70 of HeLa cells, and has specific cytotoxic activity against HeLa cell.