[Study on chemical constituents from branches and leaves of Polyalthia nemoralis].

OBJECTIVE: To investigate the chemical constituents of the branches and leaves of Polyalthia nemoralis. METHOD: The compounds were isolated and purified by silica gel, macroporous adsorption resin and Sephadex LH-20 column chromatographic methods. Their chemical structures were elucidated on the basis of physicochemical properties and spectral data. RESULT: Fourteen compounds were isolated and identified as syringic acid (1), 3-methoxy-4-hydroxycinnamic acid (2), vanillic acid (3), 4-hydroxybenzoic acid (4), mauritianin (5), (+)-xylopinidine (6), (+)-oblongine(7), (+)-tembetarine (8), eythritol (9), D-mannitol (10), ethyl-beta-D-glucopyranoside (11), (+)-magnoflorine (12), stepharanine (13), (2S, 4R)-4-hydroxy-2-piperidine-carboxylic acid (14), respectively. CONCLUSION: All the compounds were isolated from the genus Polyalthia for the first time; compounds 6 and 13 showed inhibitation activities against multi tumor cell lines.

[Chemical constituents of Ammopiptanthus mongolicus].

OBJECTIVE: To study the chemical constituents of aerial parts of Ammopiptanthus mongolicus. METHOD: Isolation and purification were carried out on silica gel, Sephadex LH-20 and HPLC column chromatography. The structures of the compounds were identified by physico-chemical properties and spectral analysis. RESULT: Nine compounds were isolated and identified as (+)-maackiain (1), brevifolin (2), 7-hydroxy-4'-methoxy isoflavanone (3), daidzein 4',7-diglucoside (4), genistein 4', 7-di-O-beta-D-glucoside (5), isolupalbigenin (6), ononin (7), beta-sitosterol (8), beta-daucosterol (9). CONCLUSION: Compounds 2, 4 - 6 were obtained from the genus Ammopiptanthus for the first time.

Mixed-mode retention mechanism for (-)-epigallocatechin gallate on a 12% cross-linked agarose gel media.

The adsorption behaviour of (-)-epigallocatechin gallate (EGCG), the major polyphenolic substance in green tea extracts, on the cross-linked agarose gel Superose 12 HR 10/30, has been studied using a variety of solvent systems and shown to be based on a mixture of hydrogen bonding and hydrophobic interaction. The hydrogen bonding was studied in acetonitrile in the presence of different co-solvents possessing varying hydrogen bond donor (HBD) and/or hydrogen bond acceptor (HBA) characteristics. The HBA-value of the co-solvent had the highest effect whereas the HBD-value played a subordinate role. Retention due to hydrophobic interaction could be demonstrated when mobile phases containing high water content were applied. The retention of EGCG, and its analogues (-)-epigallocatechin (EGC) and (-)-catechin (C) were thus shown to be dependent on the polarity of the organic modifiers added. However, the elution order of EGC and C, was inversed to that observed in reversed phase chromatography, indicating that some hydrogen bonding was still in effect. The retardation of EGCG in the presence of a wide concentration range of acetonitrile in water confirmed the interpretation that the retention mechanism is of mixed-mode character based on both hydrogen bonding and hydrophobic interaction.

Purification and characterisation of an extracellular fructan beta-fructosidase from a Lactobacillus pentosus strain isolated from fermented fish.

Lactobacillus pentosus B235, which was isolated as part of the dominant microflora from a garlic containing fermented fish product, was grown in a chemically defined medium with inulin as the sole carbohydrate source. An extracellular fructan beta-fructosidase was purified to homogeneity from the bacterial supernatant by ultrafiltration, anion exchange chromatography and hydrophobic interaction chromatography. The molecular weight of the enzyme was estimated to be approximately 126 kDa by gel filtration and by SDS-PAGE. The purified enzyme had the highest activity for levan (a beta(2-->6)-linked fructan), but also hydrolysed garlic extract, (a beta(2-->1)-linked fructan with beta(2-->6)-linked fructosyl sidechains), 1,1,1-kestose, 1,1-kestose, 1-kestose, inulin (beta(2-->1)-linked fructans) and sucrose at 60, 45, 39, 12, 9 and 3%, respectively, of the activity observed for levan. Melezitose, raffinose and stachyose were not hydrolysed by the enzyme. The fructan beta-fructosidase was inhibited by p-chloromercuribenzoate, EDTA, Fe2+, Cu2+, Zn2+ and Co2+, whereas Mn2+ and Cu2+ had no effect. The sequence of the first 20 N-terminal amino acids was: Ala-Thr-Ser-Ala-Ser-Ser-Ser-Gln-Ile-Ser-Gln-Asn-Asn-Thr-Gln-Thr-Ser-Asp-Val-Val. The enzyme had temperature and pH optima at 25 degrees C and 5.5, respectively. At concentrations of up to 12% NaCl no adverse effect on the enzyme activity was observed.

Determination of the distribution of selenium between glutathione peroxidase, selenoprotein P, and albumin in plasma.

A chromatographic method is described to determine the distribution of selenium between selenoprotein P, glutathione peroxidase (GSH-Px), and albumin in plasma, using two small columns of heparin-Sepharose and reactive blue 2-Sepharose linked together in tandem. One milliliter of plasma was diluted to 12 ml with 0.02 M sodium phosphate buffer, pH 7.0 (the equilibration buffer), applied to the heparin-Sepharose column, and eluted at a flow rate of 30 ml per hour. GSH-Px was not retained by either of these columns but selenoprotein P was retained by heparin-Sepharose and albumin by reactive blue. After the two columns were separated, selenoprotein P was eluted with heparin from heparin-Sepharose and albumin eluted from reactive blue with high salt. Analytical work confirmed the presence of selenoprotein P, GSH-Px, and albumin in the respective fractions. When rats were injected with 75Se as either selenite or selenomethionine most of the radioactivity was incorporated into the selenoprotein P fraction, with the next greatest amount into GSH-Px, and the least amount into albumin. Slab gel electrophoresis was used to determine that most of the selenium in each of the three fractions was associated with each of these selenium containing proteins. This method indicated that the majority of the selenium in plasma is associated with selenoprotein P, and the only time this was found not to be true was with high levels of dietary selenomethionine.

Separation of human IgA1 and IgA2 using jacalin-agarose chromatography.

A lectin isolated from the tropical jackfruit, jacalin, previously reported to precipitate human immunoglobulin A (IgA), and conjugated to agarose was used to separate the two subclasses of IgA from secretions. Jacalin-agarose binds specifically to the D-galactose moiety of IgA1 but not to IgA2 which has a different carbohydrate content and structure. IgA2 passed through the jacalin-agarose column and was collected in the void volume. IgA1 was eluted from the lectin by 0.8 M galactose. Of a representative diluted anti-alpha chain-purified colostral IgA preparation containing 50.2 micrograms IgA1 and 55.8 micrograms IgA2, 40.3 micrograms IgA1 (80.3% of the original) and 49.6 micrograms IgA2 (88.9%) was collected following jacalin-agarose chromatography. The jacalin-purified IgA1 fraction contained 8.0% IgA2 and the IgA2 fraction contained no IgA1. In addition, the IgA1 and IgA2 fractions had naturally occurring antibody activity to a normal oral bacterium. The method is easy, reproducible and specific and has many applications to mucosal immunological investigations.