High purity polysaccharide of pachyman was isolated from the powder of Poria cocos sclerotium with an yield of 77.8%. The intrinsic viscosity of polysaccharide was found to be 78.95 mL/g in DMSO solution at 25℃. The ...High purity polysaccharide of pachyman was isolated from the powder of Poria cocos sclerotium with an yield of 77.8%. The intrinsic viscosity of polysaccharide was found to be 78.95 mL/g in DMSO solution at 25℃. The isolated polysaccharide was reacted with chlorosulfonic acid to obtain pachyman sulfate using the improved Wolfrom method. The results of the orthogonality experiment on the sulfation reaction identified that the effectiveness of the reaction conditions on the degree of sulfation and the value of intrinsic viscosity is in the following order： molar ratio of chlorosulfonic acid to glucoside （3-5） 〉 reaction temperature （60-80℃） 〉 reaction time （1 2 h）, The kinetic studies of the pachyman sulfation indicated that the hydrolysis is accompanied with the sulfation process. The decrease in intrinsic viscosity of the sulfated pachyman is proportional to the increase in the degree of sulfation under the mild reaction conditions of 〈 80℃, chlorosulfonic acid/glucoside mole ratio 〈 5, and reaction time 〈 2 h. Beyond the above reaction conditions, excessive loss of --OH group occurs during hydrolysis. The NMR results indicated a complete sulfation on C-6 and a partial sulfation on the C-2 and C-4 of glucoside.展开更多
Pachyman based nanoparticles loading salicylic acid as model drug （SA-PNPs） were prepared by an inverse microemulsion crosslinking approach using epichlorohydrin （ECH） as crosslinker. The effects of crosslinking r...Pachyman based nanoparticles loading salicylic acid as model drug （SA-PNPs） were prepared by an inverse microemulsion crosslinking approach using epichlorohydrin （ECH） as crosslinker. The effects of crosslinking reaction time, initial volume ratio of oil to aqueous phase and dosage of crosslinker on the particle size of SA-PNPs were optimized by orthogonal experimental design. SA-PNPs prepared under the optimal conditions had the average size of 230 nm and high encapsulation efficiency of 90%. The in vitro drug release was also investigated and the release data were analyzed using zero order, first order and Higuchi＇s kinetics model. According to the determined coefficients, release data fitted to Higuchi＇s model, which suggested that the release of SA from SA-PNPs in phosphate buffer （pH 7.4） was diffusion controlled release. The experimental results indicated that pachyman possesses a promising potential to be applied as nanocarriers for controlled drug release.展开更多
文摘High purity polysaccharide of pachyman was isolated from the powder of Poria cocos sclerotium with an yield of 77.8%. The intrinsic viscosity of polysaccharide was found to be 78.95 mL/g in DMSO solution at 25℃. The isolated polysaccharide was reacted with chlorosulfonic acid to obtain pachyman sulfate using the improved Wolfrom method. The results of the orthogonality experiment on the sulfation reaction identified that the effectiveness of the reaction conditions on the degree of sulfation and the value of intrinsic viscosity is in the following order： molar ratio of chlorosulfonic acid to glucoside （3-5） 〉 reaction temperature （60-80℃） 〉 reaction time （1 2 h）, The kinetic studies of the pachyman sulfation indicated that the hydrolysis is accompanied with the sulfation process. The decrease in intrinsic viscosity of the sulfated pachyman is proportional to the increase in the degree of sulfation under the mild reaction conditions of 〈 80℃, chlorosulfonic acid/glucoside mole ratio 〈 5, and reaction time 〈 2 h. Beyond the above reaction conditions, excessive loss of --OH group occurs during hydrolysis. The NMR results indicated a complete sulfation on C-6 and a partial sulfation on the C-2 and C-4 of glucoside.
基金Funded by the Chen Guang Foundation of Scientif ic and Technologic Council of Wuhan (20055003059-21)the Fundamental Research Funds for the Central Universities (3082014)
文摘Pachyman based nanoparticles loading salicylic acid as model drug （SA-PNPs） were prepared by an inverse microemulsion crosslinking approach using epichlorohydrin （ECH） as crosslinker. The effects of crosslinking reaction time, initial volume ratio of oil to aqueous phase and dosage of crosslinker on the particle size of SA-PNPs were optimized by orthogonal experimental design. SA-PNPs prepared under the optimal conditions had the average size of 230 nm and high encapsulation efficiency of 90%. The in vitro drug release was also investigated and the release data were analyzed using zero order, first order and Higuchi＇s kinetics model. According to the determined coefficients, release data fitted to Higuchi＇s model, which suggested that the release of SA from SA-PNPs in phosphate buffer （pH 7.4） was diffusion controlled release. The experimental results indicated that pachyman possesses a promising potential to be applied as nanocarriers for controlled drug release.
