Study On Antioxidation And Anti-diabetic And Lipid-lowering Activity Of Olive Leaf

Biological activity of olive leaves was closely related to the type and content of active substances;The types and contents of active substances of olive leaves were affected by olive varieties,environment and harvest time and so on,while they were also affected by post-processing such as treatments of drying and extraction;Biological activity evaluation results were affected by activity evaluation methods and mechanisms.In this paper,antioxidant activity of 19 kinds of olive leaf with same location and age of the trees was collected,firstly,the antioxidant activity was evaluated comprehensively using chemical and cytology method;the inhibition activity ofɑ-amylase was also assessed;secondly,the content of active substance of 19kinds of olive leaf was analyzed,and the relationship between content and activity was studied.Lastly,the anti-diabetic and Lipid-lowering activity of olive leaf extracts was further studied in T2DM rats.This study will provide experimental data and theoretical basis for the development and utilization of olive leaf and its related products.Main research contents as follows:（1）Scavenging DPPH·and iron reduction abilityWith VC and oleuropein as positive control.19 kinds of olive leaves had the ability of scavenging DPPH·and iron reduction.The order of ability to scavenge the DPPH·was VC>oleuropein>19 kinds of olive leaf extracts,the IC₅₀0 was 9.66μg/ml,43.65μg/ml,0.24 mg/ml-0.69 mg/ml,respectively,with Kenxin Franfoio had the highest scavenging DPPH·activity with the IC₅₀0 was 0.24 mg/ml while Beila had the lowest scavenging DPPH·activity with the IC₅₀0 was 0.69 mg/ml among 19 kinds of olive leaves;The order of iron reduction ability was VC>oleuropein>19 kinds of olive leaf extracts.The iron reduction ability of the VC and oleuropeint was equal to Fe SO₄ with 142.09μmol/L and 106.00μmol/L respectively at the concentration of 16μg/ml;The iron reduction ability of olive leaf was108.90μmol/L-282.23μmol/L FeSO₄ equivalent at the concentration of 0.3 mg/ml,with Patrini-3had the highest iron reduction activity while Arbosana had the lowest.The ability of scavenging DPPH·and iron reduction of 19 kinds of olive leaves was difference significantly,RSD%was25.83%and 25.28%respectively.（2）Inhibition the hemolysis activity of erythrocyteWith VC and oleuropein as positive control.19 kinds of olive leaves had the inhibition activity of erythrocyte hemolysis.The IC₅₀0 was23.56μg/ml,39.52μg/ml,0.75 mg/ml-2.41 mg/ml,respectively,with Qiemulaer had the highest activity with IC₅₀0 was 0.75 mg/ml while Beila had the lowest.The inhibition ability of erythrocyte hemolysis of 19 kinds of olive leaves was difference significant,RSD%was 30.79%.（3）Inhibition the activity ofɑ-amylaseWith acarbose as positive control,the inhibitory rate of acarbose onα-amylase was 50%at the concentration was 0.8 mg/ml.19 kind of olive leaf extracts could inhibiteα-amylase activity at the concentration of 20 mg/ml,the inhibitory rate was1.32%-46.95%,with Kenxin Franfoio had the highest activity while Arbosana had the lowest.The inhibition ability ofα-amylase activity of 19 kinds of olive leaves was difference significantly,RSD%was 73.17%.（4）Active ingredient analysisThe content of oleuropein in 19 kinds of olive leaves was1.69 g/kg-33.65 g/kg,with Chenggu 32 had the highest content while Beila had the lowest;The content of total flavonoids was 4.98 g/kg-9.44 g/kg,with Ezhi 8 had the highest while Leccino had the lowest;The content of cynaroside was 0.43 g/kg-1.51 g/kg,with Ezhi 8 had the highest while Kenxin Franfoio had the lowest;The content of Apigenin-7-O-β-D-glucopyranoside was（33.32-317.87）×10^-33 g/kg,with Huaou 9 had the highest while Keji had the lowest;The content of Apigenin-7-O-β-D-glucopyranoside,oleuropein,cynaroside and total flavonoids in 19 kinds of olive leaves was difference significantly,the RSD%was 64.98%,63.50%,35.76%and 16.93%respectively.The effects of varieties on the content of apigenin-7-O-β-D-glucopyranoside and oleuropein were significant.A multiple linear relationship between the scavenging rate of DPPH·and the oleuropein,total flavonoids and the interaction was found（R²=0.5314,P<0.05）;The multiple linear relationship between the iron reduction ability and the oleuropein,total flavonoids was found（R²=0.7,P<0.05）;The linear relationship between the inhibition ability of erythrocyte hemolysis and the oleuropein,total flavonoids and the interaction was found（R²=0.4301,P<0.05）;A weak linear relationship between the inhibitory rate ofα-amylase and the oleuropein was found（R²=0.2109,P<0.05）;A linear relationship between the scavenging rate of DPPH·and the inhibitory rate ofα-amylase was found（R²=0.4764,P<0.05）.（5）Effects of olive leaf extracts on blood glucose and lipid in type 2 diabetes mellitus（T2DM）rats.Metformin as a positive drug.After intragastric administration of olive leaf extracts（500,250,125 mg/kgBW）in rats,the blood glucose of T2DM rats decreased significantly（P<0.05）.The olive leaf extracts significantly improved glucose and insulin tolerance and enhanced insulin sensitivity of T2DM rats（P<0.05）.The olive leaf extracts can regulate blood lipid by reducing the content of TG,TCHO,NEFA,LDL-C and GSP in blood of T2DM rats.Compared with metformin group,the high dose group（500 mg/kgBW）of olive leaf extracts could increase the content of HDL-C（P<0.05）.The experimental results showed that the olive leaf extracts had the effect of reducing sugar and lipid.