Preparation And Bioactivity Study Of Inulin Derivatives Of Coumarin

Inulin is a kind of natural polysaccharide widely existing in nature.It is a kind of renewable plant polysaccharide.Because of its good physicochemical properties and biological functions,as well as its biocompatibility,low cost and easy availability,it is widely used in feed,food health care,chemical industry,bioenergy and medicine and other fields.It is of great scientific significance for the utilization and exploitation of inulin as a renewable biological resource.Although the development of chrysanthemum in our late,although has been widely used in food processing industry,but some fields of research just started,the future development potential is still huge.Coumarin is an important medicinal product with many biological activities,especially its antioxidant and antibacterial activities,while inulin has good biocompatibility and other characteristics,but some of its activities are poor.At present,derivatives of inulin can effectively expand its application range,and it is also a research hotspot in recent years.In this paper,based on natural inulin,combined with the cutting-edge technology and methods related to polysaccharides in the academic field,the theory of activity superposition,targeted chemical modification,and according to the different access methods of coumarin,three series of coumarin-based inulin derivatives were designed and synthesized to make them have different biological activities and enhance the application range and use value of inulin.The first type of inulin derivatives uses affinity substitution reaction to directly connect coumarin to inulin molecules,and the second type of inulin derivatives uses long chains to connect coumarin to inulin molecules,and long chains are conducive to the exposure of active groups to improve the activity of inulin derivatives.The third is to use the Click reaction to form triazole to add coumarin to the inulin molecule.The conditions of these three synthesis methods are mild and the products are single.The prepared derivatives were characterized and identified by infrared spectroscopy and nuclear magnetic resonance spectroscopy,and then the biological activity was tested to study their antioxidant activity and antibacterial activity,and the cytotoxicity of some derivatives was determined in vitro.Firstly,the antioxidant activities of three coumarin derivatives were determined by DPPH free radical scavenging experiment,PTIO free radical scavenging experiment,superoxide anion free radical scavenging experiment and reducing capacity determination experiment.The test results showed that the antioxidant activity of raw inulin was poor,and the antioxidant capacity was all below 20%.Compared with it,the antioxidant activity of the three target derivatives was improved,and there was a positive correlation between the antioxidant activity of the target derivatives and the sample concentration,which increased with the increase of the sample concentration,among which the antioxidant activity of the second and third derivatives was significantly increased.At the highest concentration,the scavenging capacity of some inulin derivatives can reach 100%.This may be because the long chain and triazole are more conducive to the exposure of the active groups of coumarin.The second type of inulin derivatives were tested for antifungal activity and cytotoxic activity,and the tested strains were Fusarium oxysporum and Fusarium graminearum.The experimental results showed that after chemical modification,its derivatives showed significantly higher inhibitory activity against fungi than inulin,and they had almost no toxicity to cells,and had good biocompatibility.Bacteriostatic activity of Class I and Class III inulin derivatives was tested.Two common bacteria,Escherichia coli and Staphylococcus aureus,were selected,and MIC and MBC values of inulin were both >16 mg/mL,which could not inhibit bacteria,while the antibacterial activity of the first type of inulin derivatives was improved to a certain extent,and the third type of inulin derivatives had strong antibacterial activity.Therefore,it can be inferred that the access of coumarin could improve the antibacterial activity of inulin.Triazole can better expose the active groups,so that the antibacterial activity of inulin is significantly improved.