Antioxidant Capacities And Inhibitory Effects Of Phenolic Compounds Of Main Jin Cheng Cultivars Of Chongqing

Citrus sinensis Osbeck cv JinCheng belonging to the Rutaceae citrus plants is one of the sweet orange(Citrus sinensis(L.)Osbeck)varieties.JinCheng is rich in polyphenols,such as flavonoids,phenolic acids,etc.,which have functions of antioxidant,anti-inflammatory,prevention of cardiovascular disease,diabetes and other effects.Phenolics are kinds of natural plant biological antistaling agent,which have good inhibition effect on the pathogenic bacteria such as P.digitatum and P.italicum.At present,there are few studies on the phenolic composition and contents,antioxidant activity and antibacterial effects of different parts of local Jincheng fruits.This study took the peel and pulp of 5 main Jincheng cultivars of Chongqing as objects.Phenolic compounds in the peel and pulp of cultivars were extracted by methanol with ultrasonic assisted.The total phenolic and the total flavonoid contents were determined using ultraviolet spectrophotometer.Phenolic composition and content were detected by high performance liquid chromatography(HPLC),then standard chromatography maps were used for the qualitative and quantitative analysis.Their antioxidant capacities were comparative analysised using DPPH,FRAP,ABTS methods.The inhibitory effect of phenolics in peel and pulp of various cultivars were tested by toxic medium assays.At the same time,mycelium growth rate method was used to determine the minimum inhibitory concentration.The main results were as follows:(1)The total flavonoids average contents(12.77 mg/g)in peel of the 5 cultivars were higher than the total phenolic contents(7.12 mg/g).The total flavonoids contents were highest in Citrus sinensis Osbeck cv.Jin Ch ?Pengan 100‘ and the total phenolic contents were highest in Citrus sinensis Osbeck cv.Jin Ch ?Fuling‘.The total flavonoids average contents(5.47 mg/g)in pulp of the 5 cultivars were higher than the total phenolic contents(4.22 mg/g).The total phenolic contents and the total flavonoid contents were highest in Citrus sinensis Osbeck cv.Jin Ch ?Fuling‘.(2)A total of 10 flavonoids compounds were tested from peels of 5 local cultivars.Hesperidin(75.52 mg/g DW),naringenin(3.46 mg/g DW),nobiletin(3.12 mg/g DW)and diosmetin(2.61 mg/g DW)were the main compositions among 10 flavonoids in peels of different local cultivars.Citrus sinensis Osbeck cv.Jin Ch ?Pengan 100‘ had the highest hesperidin and naringenin contents.Citrus sinensis Osbeck cv.Jin Ch ?Beibei 447‘ had the highest nobiletin contents.Citrus sinensis Osbeck cv.Jin Ch ?Tongshui 72-1‘ had the highest nobiletin contents.Howere,there were 8 flavonoids compounds which detected in the pulp.The main ingredients of flavonoids in pulps of different local cultivars were naringenin(4.54 mg/g DW)and hesperidin(38.40 mg/g DW).Citrus sinensis Osbeck cv.Jin Ch ?Pengan 100‘ had the highest hesperidin and Citrus sinensis Osbeck cv.Jin Ch ?Fuling‘ had the highest naringenin contents.A total of 4 phenolic acids compounds were tested from peels and pulps of 5 local cultivars.4 phenolic acids contained gallic acid,chlorogenic acid,ferulic acid and caffeic acid.The highest content among 4 kinds of phenolic acids was gallic acid.The peel of Citrus sinensis Osbeck cv.Jin Ch ?Fuling‘ and the pulp of Citrus sinensis Osbeck cv.Jin Ch ?Kaixian‘ all had the highest gallic acid contents.(3)The phenolics in the peel and pulp of the 5 cultivars fruits had antioxidant activity measured by DPPH,FRAP and ABTS methods.The DPPH value comparison of peel were lower than of pulp about 5 cultivars,but the FRAP and ABTS value comparison of peel were higher than of pulp.The peel of cultivar who had the strongest comprehensive antioxidant capacity was Citrus sinensis Osbeck cv.Jin Ch ?Pengan 100‘.Howerer,the pulp of cultivar who had the strongest comprehensive antioxidant capacity was Citrus sinensis Osbeck cv.Jin Ch ?Fuling‘.(4)The phenolic extracts in peel and pulp of different cultivars had strong inhibitory effects on mold.The peel of Jin Ch ?Pengan 100‘ and the pulp of Jin Ch ?Fuling‘ had strong inhibitory effects on P.digitatum and P.Italicum.The MIC of P.digitatum was 2.6 mg/mL that was lower than of P.Italicum(5.2 mg/mL).Thus the sensitivity of P.digitatum was stronger than P.Italicum.