Synthesis And Functional Study Of Novel Spin Trap And Nano-antioxidant

Reactive oxygen-centered radical (ROS) plays a key role in numerous physiological processes. The detection and scavenging of excess free radicals play an important role in biology and medicine. Although spin traps are widely used in free radical detection in vitro, there are still several limitations on its applications in vivo because of the low accumulation in the site of radical production area(s) . Antioxidants can effectively scavenge the the excess free radicals in vivo and play an important role in maintaining the redox balance. However, antioxidant has low oral bioavailability because of the dominated position of the efflux mechanism in digestive system. To solving these problems. we designed and systhesized two novel spin traps and two novel nano gold antioxidant.(1) Two novel nitrone spin-traps, DSC-PBN (N-(4-(((2, 5-dioxopyrrolidin-1–yloxy)carbonyloxy)methyl)benzylidene)-2-methylpropan-2-N-oxide) and L-tyr- EMPO(L-tyrosine methyl -pyrroline-N-oxide), was designed and synthesized in this work. The structure of the nitrone was characterized using UV, MS and 1H NMR. ESR results show that DSC-PBN can efficiently trap carbon centered free radicals and their ESR spectra can be readily recognized, but it could not detect the O2-. which is the most important in organism.Various radicals, including O2-., .OH , .OR, and .R, have been efficiently detected and characterized using L-tyr-EMPO. The half-life of the L-tyr-EMPO superoxide adduct was estimated to be 6.5min. This new way of covalent bonding can be applied to almost all proteins or peptides with the N-terminal modified. Above all, with mild condition, wouldn’t led to protein (or antibody) denaturation.(2) Two novel nano gold -antioxidant Au@PEG3danshensu and Au-danshensu-GA were designed, synthesized and characterized by IR, UV, TEM and XPS.. The transmission electron microscopy (TEM) image shows that the size of the nanoparticles is 4.5nm and 110nm. DPPH. (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging experiments revealed that the rate constant for the reaction of Au@PEG3danshenus with DPPH. was about 8.93 times greater than that of danshesu alone, the IC50 for .OH scavenging activity was 714μM. These two nano-antioxidant had high biocompatibility and no cytotoxicity thus paving the way for nano-antioxidant in the application of biomedicine.