Research On Antioxidant Activity And Anti-proliferative Activity Against Hep G2 Cells Of Three Varieties Of Blueberry

Blueberry is a perennial shrub-type small berry of Ericaceae and Vaccinium spp.that with a very high nutritional value and rich in various antioxidant bioactive compounds.In this paper,the content of bioactive compounds,antioxidant activity and anti-proliferative activity against Hep G2 cells of wild blueberry（Vaccinium uliginosum L.）from Greater Khingan Mountains（hereinafter referred to as the wild blueberry）,Guizhou blueberry（Vaccinium ashei Reade）and Chilean blueberry（Vaccinium corymbosum L.）were studied and the results were as follows:1.Comparison of bioactive compounds of three blueberriesThe moisture content,fresh weight,diameter,soluble solids,titratable acid and total polyphenol,total flavonoid content of wild blueberry,Guizhou blueberry and Chilean blueberry were analyzed,and their anthocyanin contents were analyzed by high performance liquid chromatography.The results showed that the average weight and diameter of wild blueberry were significantly lower than that of Guizhou blueberry and Chilean blueberry（p<0.05）,but there was no significant difference in water,soluble solids and titratable acid content of the three blueberries（p>0.05）.Wild blueberry had the highest contents of total polyphenol,total flavonoid and total anthocyanin.The order of total polyphenol contents was wild blueberry（1998.34±54.65 mg GAE/100 g DW）,Guizhou blueberry（1319.26±24.01 mg GAE/100 g DW）and Chilean blueberry（958.69±40.87 mg GAE/100 g DW）.The order of total flavonoid contents was wild blueberry（2065.56±38.46 mg RE/100 g DW）,Guizhou blueberry（1303.87±60.81 mg RE/100g DW）and Chilean blueberry（1037.67±25.52 mg RE/100 g DW）.The order of total anthocyanin contents was wild blueberry（14923.13±23.04μg/g DW）,Guizhou blueberry（14648.20±28.12μg/g DW）and Chilean blueberry（8063.58±18.90μg/g DW）（p<0.05）.2.Evaluation of antioxidant activity of three blueberriesThe antioxidant activities of wild blueberry,Guizhou blueberry and Chilean blueberry extracts were evaluated by in vitro chemical antioxidant methods（DPPH assay,ABTS assay,FRAP assay,ORAC assay）and cellular antioxidant method（CAA assay）.The results showed that the wild blueberry had the strongest antioxidant activity among the three blueberries.Wild blueberry（342.82±14.82μmol TE/g DW）had the highest DPPH value,followed by Guizhou blueberry（184.88±9.83μmol TE/g DW）and Chilean blueberry（159.65±11.34μmol TE/g DW）.Wild blueberry（342.48±10.33μmol TE/g DW）had the highest FRAP value,followed by Guizhou blueberry（204.51±9.37μmol TE/g DW）and Chilean blueberry（171.88±13.22μmol TE/g DW）.And wild blueberry had the highest ABTS value（276.41±7.84μmol TE/g DW）and ORAC value（488.86±17.13μmol TE/g DW）.There was no significant difference between the ABTS value of Guizhou blueberry（183.28±16.43μmol TE/g DW）and Chilean blueberry（167.86±10.76μmol TE/g DW）（p>0.05）.Similarly,there was no significant difference between the ORAC value of Guizhou blueberry（281.46±9.37μmol TE/g DW）and Chilean blueberry（221.65±14.20μmol TE/g DW）（p>0.05）.The CAA results showed that in the“No PBS wash”protocol,the wild blueberry had the highest CAA value（1349.99±42.19μmol QE/100 g DW）,while there was no significant difference between Guizhou blueberry（579.36±21.03μmol QE/100 g DW）and Chilean blueberry（602.24±30.88μmol QE/100 g DW）（p<0.05）.In the“PBS wash”protocol,the order of CAA value was the same as“No PBS wash”protocol.In the“No PBS wash”protocol,the EC₅₀values were as follws:Guizhou blueberry（3.25±0.07 mg/mL）≈Chile blueberry（3.17±0.05mg/mL）>Wild blueberry（1.26±0.05 mg/mL）.In the“PBS wash”protocol,the order of EC₅₀value was the same as“No PBS wash”protocol.The correlation coefficients of total polyphenols and total flavonoids with DPPH values were 0.975 and 0.991（p<0.01）,respectively.The correlation coefficients with ABTS values were 0.970 and 0.984（p<0.01）,respectively.The correlation coefficients with ORAC values were 0.939 and 0.967（p<0.01）,respectively.The correlation coefficients of total polyphenols,total flavonoids and total anthocyanins with FRAP values were 0.985,0.996（p<0.01）and0.670（p<0.05）,respectively.In the“No PBS wash”protocol,the correlation coefficients of total polyphenols and total flavonoids with CAA values were 0.930 and 0.962（p<0.01）,respectively.In the“PBS wash”protocol,the correlation coefficients of total polyphenols and total flavonoids with CAA values were 0.970 and 0.986（p<0.01）,respectively.3.Anti-proliferative activity against Hep G2 cells of three blueberriesThe proliferation inhibitory activities of wild blueberry,Guizhou blueberry and Chilean blueberry extract on Hep G2 cells were compared.The results showed that the extracts of three blueberries could significantly inhibit the proliferation of Hep G2 cells.At the test concentrations（5,10,15,20,25,30,35,40 mg/mL）,the inhibition rate of Hep G2 cell proliferation of the three blueberry extracts increased with increasing concentration.Wild blueberry extract had the strongest proliferation activity(EC₅₀=21.36±1.07 mg/mL),while there was no significant difference between Guizhou blueberry(EC₅₀=31.29±2.03 mg/mL)and Chilean blueberry(EC₅₀=30.08±1.87 mg/mL)（p>0.05）.The correlation coefficients of total polyphenols,total flavonoids and EC₅₀0 values were–0.825 and–0.868（p<0.01）,respectively,and the correlation coefficients of total anthocyanins and EC₅₀ values was–0.411（p>0.05）.