Feather Keratin Metal Complex Antioxidant Performance Study

Superoxide dismutases （SOD）, as the first antioxidant enzymes, which works inthe process of scavenging the reactive oxygen species （ROS）, plays an important rolein keeping dynamic balance between generation and elimination of the superoxideanion radical (O₂^·-). SOD can protect cells against destruction of its structure andfunction, which keep cells free from oxidative damage. At present, works on SODmimic are mostly focused on the enzyme activity center which are on the basis ofquasi-porphyrin metal complexes. Some of these small molecule metal complexes hadexcellent ROS scavenging activity, while most of them were bad biocompatibility andpoor water solubility or even harmful for organism. Their application was limited.Thus, SOD mimic undergo the steps from small molecules metal complexes tomacrocyclic and macromolecules conjugation. Now, it has shifted from active centresimulation to whole function mimic. The enzyme mimics which are on the basis ofpolymers not only modeled the core structure of natural enzyme but also modeled themicroenvironment of natural enzyme. In order to overcome the shortcoming, featherkeratin were used as scaffold. Small molecular oxygen-free radical scavengers, suchas amino acids and metal salts, were combined as active centre. In this way, a kind offeather keratin-metal complex conjugation was prepared. Their oxidant scavengingactivity was investigated.Firstly, this paper reviews the achievement on the macromolecules SOD mimics,including proteins and peptide, polysaccharide, micelle and liposome, syntheticpolymers.Secondly, a new kind of feather keratin binding metal complexes（FKM, M=Zn^Ⅱ，Cu^Ⅱ，Mn^Ⅱ，Ni^Ⅱ） were prepared. Feather keratin/metal complexes（FKM） werecharacterized by UV-Vis spectra and circular dichroism spectra. The superoxide anionradical (O₂^·-) scavenging activity of FKM complexes was investigated. The result ofradical scavenging activity was compared with natural Cu,Zn-SOD. FKCu complexesshowed excellent scavenging activity.Thirdly, a new kind of feather keratin-amino acid composite binding metalcomplex compounds（FK-GlyM, M=Zn^Ⅱ，Cu^Ⅱ，Mn^Ⅱ，Ni^Ⅱ） were prepared. The superoxide anion radical (O₂^·-) scavenging activity of FK-GlyM complex compoundswas investigated. The result of radical scavenging activity was compared with naturalCu,Zn-SOD. FK-GlyCu complexes showed excellent scavenging activity.Finally, a different kind of feather keratin-amino acid composite binding metalcomplex compounds（FK-HisM, M=Zn^Ⅱ，Cu^Ⅱ，Mn^Ⅱ，Ni^Ⅱ） were prepared. Thesuperoxide anion radical (O₂^·-) scavenging activity of FK-HisM complex compoundswas investigated. The result of radical scavenging activity was compared with naturalCu,Zn-SOD. FK-HisCu complexes showed excellent scavenging activity.In summary, a new kind of biopolymer O₂^·- scavenging complexes was prepared.The complexes had excellent O₂^·- scavenging activity and water solubility. Theresults give us a new idea for research on biopolymer antioxidant reagents. Studies ofthe simulation strategies will provide a new idea of designing and exploiting anew-type biocompatible and high reactive antioxidants.