Compositions,Separation And Purification Of Flavonoids In The Peels Of Sweet Oranges Cultivated In Chongqing

Sweet Oranges?Citrus sinensis?L.?Osbeck?are one of the important cultivars of citrus,eaten freshly or processed as orange juice.After processing,there are lots of by-products which caused a serious waste of resources.Many studies have shown that sweet oranges peel were rich in flavonoids,which have a lot of bioactivities such as of antioxidant,anti-inflammatory,anti-aging,and preventing chronic diseases.In this study,the flavonoids of 13 sweet orange peel major Cultivated in Chong Qing were analyzed,and the content of flavonoids were also determined by high performance liquid chromatography?HPLC?.The effects of extraction parameters on the content of flavanone and polymethoxyflavones?PMFs?in sweet orange peel were studied to optimum the suitable extraction conditions.Besides,the total flavonoids from sweet orange peel extracts were purified by macroporous resins.Its dynamic adsorption conditions were optimized to determine the optimal process parameters.The results were summarized as follows:?1?The total flavonoid contents and total phenolic content were determined by NaNO₂-Al?NO₃?₃ and Folin-Ciocalteus colorimetric methods.The results showed that the average content of total flavonoid in the peel?9.28 mg/g?were lower than the total phenolic content?14.86 mg/g?.Among them,the total flavonoids content of Bamfild Navel Orange was the highest,and the highest total phenolic content is Powell navel orange.?2?The flavonoids of orange peel were analyzed by HPLC.The results showed that the flavonoids in the sweet orange peels were flavanones and PMFs,and hesperidin was the predominant flavanones,which was up to more than 80%.The higest content of hesperidin in Bamfild Navel Orange was up to 28.13 mg/g,and the lowest content of hesperidin in Tongshui 72-1 Jincheng was only 11.72 mg/g.Nobiletin was the highest PMFs,the highest content of methoxyflavones was S26 jincheng,Cuba Liuyecheng,and lane late navel orange.The content of PMFs of Washington Sanquine was only 0.57 mg/g,which is the lowest.?3?The antioxidant activity of peels of the 13 cultivars fruits had measured by DPPH,FRAP and ABTS methods,and the antioxidant potency composite index?APC?was used to evaluate the fruits antioxidant activity.The peel of cultivar that had the strongest comprehensive antioxidant capacity was Citrus sinensis Osbeck cv.Lane late Navel orange.?4?In the present study,the extraction efficiency of flavanones and methoxyflavones has been investigated with respect to four parameters,including solvent concentration,temperature,time,and solid-liquid ratio.Results show that the ethanol concentration and extraction temperature are the most important extraction parameters,and also there was a significant difference between the regularity of the change in the content of the flavanones andmethoxyflavones with the same extraction factor.The optimal extraction of flavanones were:70%ethanolconcentration,solid-liquid ratio of 1:20,90?extraction 4 h,the content of total flavanones can reached 24.74±0.42 mg/g;The optimum conditions of methoxyflavones were determined as follow:80%ethanolconcentration,and solid-liquid ratio of 1:10,60?extract 2 h,the yield of total methoxyflavones was 2.83±0.08 mg/g.?5?The extraction of crude flavonoids was only 3.60%by extraction with the highest content of total flavonoids.The adsorption and desorption properties of AB-8,NKA-9 and D101 of were investigated;the results indicated that the adsorption capacity of AB-8 was the highest and the desorption performance was appropriate to purify the total flavonoids.To optimize the separation process,the static and dynamic of adsorption and desorption experiments were carried out,the optimal adsorption conditions were:initial concentrations in sample solution of 0.75 mg/m L,pH of 3.0,sample loading amount of 3.5 BV,flow rate of 2BV/h.The optimal desorption parameters were 80%ethanol 5 BV,flow rate of 2 BV/h,the desorption ratio was 90.73%.After purification;the content of flavonoids in product was increased from 36.04 mg/g to 334.54 mg/g,and the total flavonoid content was 8.3 times higher than that before purification.HPLC analysis results found that the flavonoids profiles were not changed after adsorption and desorption by AB-8 macroporous resin.The main flavonoids were narirutin and hesperidin,the percentage content to the total flavonoids was91.14%.