It has been shown that acrylic monomer is easily grafted to cellulose by sodium periodate. The apparent activation energy of graft copolymerization is found to be 10.5 Kcal./mole, which indicates that polymer radicals formed by the attack of sodium periodate on cellulose initiate the graft copolymerization. The rate of the reaction increases with increasing reagent concentration of the reagent up to a certain concentration. At higher concentrations, sodium periodate produces more aldehyde groups in the graft copolymer and the grafted chains become shorter. The apparent number of graft‐initiating points is almost constant and independent of the sodium periodate concentration. Studies of homogeneous polymerization indicate that sodium periodate seems not to terminate the reaction of growing polymer radicals. On the other hand, when dialdehyde cellulose prepared previously by sodium periodate oxidation is grafted with methyl methacrylate, the grafted chain is shorter in the range of high content of aldehyde. The above observation indicates that the aldehyde groups formed in cellulose during the grafting reaction are likely to terminate the growing graft chains. The chain transfer constants for several sugars and alcohols with acrylonitrile as monomer were measured. The constants for sugars were found to be always higher than those for alcohols. The x‐ray diffraction patterns of the grafted cellulose with acrylonitrile give, in addition to the typical patterns of crystalline cellulose, lattice distances of 5.2 and about 3 A. which are attributed to the grafted polyacrylonitrile. The intensity distribution curve along the Debye‐Scherrer ring at the lattice distance of 5.2 A. leads to the conclusion that the crystallites of grafted polyacrylonitrile might be oriented along the direction of the fiber axis of the preexisting stock polymer. Studies on samples of cellulose of different fine structure would support the inference that, in the range of relatively low per cent grating the growing grafted chains on the surface of cellulose crystallites are oriented with the formation of crystallites along the lamellar plane of cellulose crystallites.
We conducted the novel synthesis of middle molecular weight heparinyl amino acid derivatives (MHADs) to reduce the adverse effect of heparin (HE) based on its anticoagulant activity. Subsequently, we investigated the radical scavenging effects of 12 kinds of MHAD on cultured human umbilical vein endothelial cells (HUV-ECs) damaged by oxygen free radicals using xanthine and xanthine oxidase in vitro. As a result, middle molecular weight heparinyl phenylalanine, middle molecular weight heparinyl leucine, and middle molecular weight heparinyl tyrosine showed significant protective effects on HUV-ECs. In conclusion, these three HE derivatives might be candidates for therapeutic agents to treat diseases attributed to peroxidation.
We have developed an analytical method for mucopolysaccharides (MSs) and a simple method for removing their impurities from un-fractionated heparin (UFH) preparations. An over-sulfated chondroitin sulfate standard (OSCS-STD) was de-polymerized with nitrous acid, as were UFH sodium salt containing OSCS and other MSs (OSHP-SH), OSCS reference standards containing heparin (CSMS-CE1 and CSMS-CE2), and various UFH products. Following de-polymerization, the molecular weight distributions of these samples were analyzed by gel permeation HPLC. The molecular weight distribution of OSCS-STD remained unchanged before and after nitrous acid depolymerization, and the molecular weight distribution of OSCS-STD was similar to that of OSHP-SH de-polymerized with nitrous acid. On the other hand, the molecular weight distributions of CSMS-CE1 and CSMS-CE2 were similar to that of standard chondroitin sulfate B. UFH sodium salt and several drug substances containing heparin and other MSs were then purified by ethanol precipitation. After nitrous acid de-polymerization, gel permeation HPLC and 1 H-NMR spectroscopy revealed that MSs resistant to de-polymerization with nitrous acid were concentrated in the supernatant and heparin was concentrated in the colloidal precipitate.
Background/Aim: We investigated the inhibitory action of medium molecular weight heparinyl phenylalanine (MHF) on type I hypersensitivity in comparison with medium molecular weight heparinyl arginine (MHR). Materials and Methods: MHF and MHR were synthesized from heparin (HE) to decrease the side-effect of HE based on its anticoagulant action and used in this study. Results: MHF demonstrated a significant inhibitory action on 48-h homologous passive cutaneous anaphylaxis in rats. Although MHF did not affect the death of mice injected with a lethal dose of histamine, it significantly prolonged the survival time of mice administered a lethal dose of compound 48/80. On the other hand, MHR did not inhibit type I hypersensitivity. Conclusion: The inhibitory action of MHF on the type I allergic reaction was due to a reduction or delay in histamine release from mast cells. MHF may be a potent anti-allergic agent.
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