Separation and purification of 9,10-dihydrophenanthrenes and bibenzyls from Pholidota chinensis by high-speed countercurrent chromatography.

Stilbenoids are the main components of leaves and stems of Pholidota chinensis. In the present investigation, high-speed counter-current chromatography was used for the separation and purification of two classes of stilbenoids, namely, bibenzyls and 9,10-dihydrophenanthrenes, on a preparative scale from whole plants of P. chinensis with different solvent systems after silica gel column chromatography fractionation. n-Hexane/ethyl acetate/methanol/water (1.2:1:1:0.8, v/v/v/v) was selected as the optimum solvent system to purify 1-(3,4,5-trimethoxyphenyl)-1',2'-ethanediol (1), coelonin (2), 3,4'-dihydroxy-5,5'-dimethoxybibenzyl (3), and 2,​7-​dihydroxy-​3,​4,​6-​trimethoxy-​9,​10-​dihydrophenanthrene (4). While 2,7-dihydroxy-3,4,6-trimethoxy-​9,​10-​dihydrophenanthrene (5), batatasin III (6), orchinol (7), and 3'-O-methylbatatasin III (8) were purified by n-hexane/ethyl acetate/methanol/water (1.6:0.8:1.2:0.4, v/v/v/v). After the high-speed counter-current chromatography isolation procedure, the purity of all compounds was over 94% assayed by ultra high performance liquid chromatography. The chemical structure identification of all compounds was carried out by mass spectrometry and (1)H and (13)C NMR spectroscopy. To the best of our knowledge, the current investigation is the first study for the separation and purification of bibenzyls and 9,10-dihydrophenanthrenes by high-speed counter-current chromatography from natural resources.

Immunogenicity and immunoprotection of recombinant PEB1 in Campylobacter-jejuni-infected mice.

AIM: To construct a prokaryotic expression vector carrying Campylobacter jejuni peb1A gene and express it in Escherichia coli. Immunoreactivity and antigenicity of rPEB1 were evaluated. The ability of rPEB1 to induce antibody responses and protective efficacy was identified. METHODS: peb1A gene was amplified by PCR, target gene and prokaryotic expression plasmid pET28a (+) was digested with BamHI and XhoI, respectively. DNA was ligated with T4 DNA ligase to construct recombinant plasmid pET28a(+)-peb1A. The rPEB1 was expressed in E. coli BL21 (DE3) and identified by SDS-PAGE. BALB/c mice were immunized with rPEB1. ELISA was used to detect the specific antibody titer and MTT method was used to measure the stimulation index of spleen lymphocyte transformation. RESULTS: The recombinant plasmid pET28a (+)-peb1A was correctly constructed. The expression output of PEB1 protein in pET28a (+)-peb1A system was approximately 33% of total proteins in E. coli. The specific IgG antibody was detected in serum of BALB/c mice immunized with rPEB1 protein. Effective immunological protection with a lower sickness incidence and mortality was seen in the mice suffering from massive C. jejuni infection. CONCLUSION: rPEB1 protein is a valuable candidate for C. jejuni subunit vaccine.