Study On The Construction And Application Of Cellular Antioxidant Activity Evaluation Model For Minor Components In Edible Vegetable Oil

Tocopherols,sterols,squalene,phenolics,and oryzanol are minor components of vegetable oil,which are both nutrients and natural antioxidants that directly affect the function and oxidative stability of the oil.Existing methods for evaluating antioxidant capacity,like chemical scavenging radicals,do not reflect the ability of minor components in regulating the redox state of cells.In this regard,the present study builds a cellular antioxidant activity(CAA)assay for the minor components of vegetable oil.The antioxidant capacity of rice bran oil during refining process and 15 kinds of common vegetable oil were evaluated by CAA model.The main research content were shown as follows:Firstly,the maximum tolerance concentration of quercetin and oil methanol extracts in HepG2 cell was determined by methylene blue assay.The standard curve of quercetin concentration-CAA value and oil methanol extracts concentration-CAA value of were established,then the effectiveness of CAA model to evaluate the antioxidant ability of vegetable oil was confirmed.The results showed that the maximum tolerated concentrations of quercetin and olive oil methanol extracts were 32μM and 5 mg/mL,respectively;the standard curves of quercetin and olive oil methanol extracts were y=22.57ln(x)-32.28(R~2=0.9811,effective range 0~32μM),y=15.58ln(x)+37.61(R~2=0.9891,effective range 0~5mg/mL),respectively;the quercetin and olive oil methanol extracts showed high correlations with the CAA values evaluated by the model(R~2>0.98).Secondly,oil samples from three different rice bran oil refineries were collected.The basic indicators of acid value(AV),peroxide value(PV)and fatty acid composition of rice bran oil were examined and discussed.The minor components including tocols,squalene,phytosterols,phenolics and oryzanol were determined to observe the concentration changes during refining process.Moreover,the effect of refining rice bran oil on antioxidant capacity was evaluated by four chemical methods(ABTS,FRAP,ORAC and DPPH)and CAA method.Besides,Pearson correlation statistics were used to study the relationships between the minor components contents and antioxidant capacity of rice bran oil.The results showed that the minor components losses were at different degree levels during refining process,and the radical scavenging activity by four chemical methods showed a corresponding decreasing trend.The results determined by ABTS,ORAC,and DPPH methods were significantly correlated with phenolics,squalene,sterol and oryzanol content(P<0.01).No significant cytotoxicity activities were observed in the 0~200 mg/mL methanol extracts of rice bran oil during the refining process.The results of CAA method of methanol extracts of rice bran oil during refining process were significantly correlated with the sterol content(P<0.05).The result of CAA method not significantly correlated with the results of four chemical methods(P>0.05).Finally,15 kinds of fresh vegetable oils(such as rice bran oil,soybean oil,olive oil,flaxseed oil,and sesame oil)without adding antioxidants were collected,and the contents of tocopherols,squalene,sterols,and phenolics were analyzed.The ORAC method and the CAA method were used to evaluate antioxidant activity of vegetable oil.Pearson correlation statistics were used to study the relationship between the minor components contents and antioxidant capacity of vegetable oil.The results showed that among the 15 kinds of vegetable oil,high-phenolic olive oil,sesame oil,and low-phenolic olive oil had the highest total phenolic contents,33.12±0.21,21.13±0.66,and 8.17±0.26 mg GAE/100 g oil,respectively;high-phenolic olive oil,sesame oil,and flaxseed oil had the highest ORAC value,which were 1778±42,1587±32 and 1092±3μmol TE/100 g,respectively.Significant cytotoxicity and anti-proliferation were observed in the 0~200 mg/mL methanol extracts of high-phenolic olive oil,low-phenolic olive oil,sesame oil and flaxseed oil.And CAA values of the four kinds vegetable oil were also significantly higher than other 11 kinds of vegetable oil(P<0.01).The correlation analysis showed that the ORAC and CAA values were significantly correlated with the phenolic content(P<0.05).There was a significant correlation between ORAC and CAA method(P<0.01).