Regio-and Stereo-Selective Synthesis,Characterization And Biological Activity Of Some Sugar Stearic Acid Monoesters

It is studied in this thesis the regio-and stereo-selective synthesis, properties, structural characterization and antioxidant and antibacterial activity, of some sugar stearic acid monoesters based on glucose, galactose and lactose.Firstly, it is the preparation of glucose(galactose, lactose) stearic acid monoesters. Sugar monoesters were prepared in this work by esterification using acetyl as protecting group. The esterification using p-toluenesulfonic acid as catalyst was then optimized through single factor experiments. The optimal conditions of esterification were obtained as follows:reaction temperature120℃, reaction time5h, molar ratio of stearic acid to3a(b,c) is3:2, mass ratio of p-toluenesulfonic to3a(b,c) is1:99.A conversion ratio of5a,5b and5c up to73.5%,71.9%,76.8%was obtained, and all of them were light brown oily. Meanwhile, another method of esterification was tried at a lower temperature, but an additional experimental procedure was needed. At last, the conclusion that the catalytic reaction is efficient and simpler operation under general comparison can be obtained. The optimal conditions of deprotection were obtained through single factor experiments as follows:20℃,15min, sodium methoxide(0.O1M), methanol solvent. A conversion ratio to6a-a,6a-β,6b-α,6b-β,6c-α and6c-p up to6.7%,87.8%,85.2%,87.7%,84.6%and89.5%was obtained, and all of them were white floc.Second, it is the confirmation and analysis of physical and chemical characters of the compounds by TLC,[α]D’, IR, ESI-MS and NMR.IR spectra showed the intensity of peaks between2922-2926cm-1,2851-2853cm-1and1637-1735cm-1were enhanced, because CH3, CH2and ester bond formed after esterification. The IR spectra of compound6a(b,c) showed-OH stretching vibration peak appears between3400-3413cm-1after deprotection. These compounds were characterized by ESI-MS,’HNMR and13CNMR. As results of analysis shown, target compounds have been preparation successfully.Lastly, it is studying and comparing on the biological activities of these compounds by antioxidant in vitro and antibacterial test. The result showed that all of the sugar stearic acid monoesters have some antioxidant and antibacterial activity, compounds showed stronger activity if the removal of protecting groups and two different kinds of configuration of the same compound so as them.