| In this study, the physiological fallen and thinned fruits of13Chinese native citrus typs were studied. High performance liquid chromatography (HPLC) was used to analyse the main composition and content of phenolics of the samples.And the radical scavenging (2,2-diphenyl-1-picrylhydrazyl radicals, DPPH), free radical oxidation (2,2’-azino-bis (3-ethylbenzthiozoline-6)-sulhonic acid, ABTS) and reduction of iron ions (ferric reducing antioxidant power, FRAP) were used to evaluate their antioxidant activity. It was aimed to provide information for the development and further utilization of the fruits. The main results were as follows:1.The contents of total phenol and flavonoids in different citrus genotypes and the different physiological fallen and thinned fruits had significant differences (P<0.05). The total phenol and flavonoids contents in the first physiological fallen fruits period were the highest. The total phenol variation range of each genotype was from2.11±0.096mg GAE(gallic acid equivalent)/g DW (dry weight) to60.598±0.252mg GAE/g DW. Total phenol content of C. paradisi Macf. was the highest, it was60.598±0.252mg GAE/g DW. The content of the thinned fruits were the lowest, and the total phenol content of C. medica L. was the lowest, it was2.11mg GAE/g DW. Variation range of total flavonoids of each genotype was from2.478±0.05mg RE (rutin equivalent)/g DW to47.061±0.71mg RE/g DW. The content of C. aurantium L. was the highest, it was47.061±0.71mg RE/g DW.The content of the thinned fruits were the lowest, and the content of C. medica L.was the lowest, it was2.478±0.05mg RE/g DW.2.Flavanone and phenolic acids were the main phenolics of the germplasms. Hesperidin and naringin were the main flavanone.The hesperidin and naringin of each citrus genotype and fruits in different periods had significant differences (P<0.05).The hesperidin of the second physiological fallen fruits period was the highest, variation range was from ND to88.472±0mg/g DW. C. grandis Osbeck had the highest hesperidin, it was88.472±0mg/g DW. The naringin of the second physiological fallen fruits had the highest content, variation range was from ND to55.476±0.124mg/g DW. C. grandis Osbeck had the higest naringin, it was55.476±0.124mg/g DW. The type and content of the phenolic acids in different genotypes of citrus and different physiological periods were different (P<0.05).The second physiological fallen fruits of C. reticulata Blanco (1.114±0.079mg/g DW), C. paradisi Macf. (0.724±0.039mg/g DW) were rich in Chlorogenic acid.The thinned fruits of C. reticulata Blanco (0.71±0.126mg/g DW) was rich in Chlorogenic acid.The first fallen physiological fruits of C. limon Burm.f.(1.916±0.062mg/g DW), C. reticulata Blanco (0.932±0.065mg/g DW), C. medica L.(0.864±0.069mg/g DW), C. reticulata Blanco (0.849±0.05mg/g DW) were rich in Caffeic acid. The phenolic acids content of each genotype in different physiological fallen fruits and thinned fruits had significant differences (P<0.05). Caffeic acid and chlorogenic acid were the main phenolic acids in physiological fallen fruits and thinned fruits. The content of caffeic acid in the first physiological fallen fruits was the highest, and variation range was from ND to2.475±0.02mg/g DW. The content of caffeic acid in C. limonia Osbeck was the higest, it was2.475±0.02mg/g DW. The content of chlorogenic acid in the first physiological fallen fruits was the highest, variation range was from ND to1.607±0.031mg/g DW. C. limonia Osbeck had the higest content, it was1.607±0.031mg/g DW. The first physiological fallen fruits of C. paradisi Macf.(1.655±0.035mg/g DW), C. grandis Osbeck (1.327±0.131mg/g DW), C. limonia Osbeck (0.635±0.114mg/g DW), C. aurantium L.(0.634±0.014mg/g DW) were rich in Gallic acid. The first physiological fallen fruits of C. junos Sied.ex Tanaka (2.027±0.01mg/g DW), C. aurantium L.(0.307±0.089mg/g DW), C. reticulata Blanco (0.255±0.035mg/g DW) were rich in ferulic acid. The second physiological fallen fruits of C. junos Sied.ex Tanaka (0.483±0.023mg/g DW) were rich in ferulic acid.3.Each genotype and different periods of the physiological fallen fruits and thinned fruits had significant antioxidant activities (P<0.05), and the antioxidant capacity of physiological fallen fruits and thinned fruits in turn were as follows:the first physiological fallen fruits> the second physiological fallen fruits> thinned fruits. In general, the antioxidant capacity of the first physiological fallen fruits of C. reticulata Blanco, C. reticulata Blanco, C. aurantium L., C. paradisi Macf, C. sinensis Osbeck were significantly higher than other genotypes and their fallen fruits and thinned fruits.4.Correlation analysis results showed that the total phenol, flavonoids and DPPH, ABTS, FRAP were extremely significant positive correlation relationship (P<0.01). DPPH and ABTS, FRAP were extremely significant positive correlation (P<0.01). ABTS, DPPH and FRAP were also extremely significant positive correlation (P<0.01).In above,each genotype and different physiological fallen fruits and thinned fruits of Chinese native citrus species were rich in phenolic compounds, and the variation range was wide. The first physiological fallen fruits were rich in phenolic compounds.On the whole,Chinese native citrus species of C. reticulata Blanco, C. reticulata Blanco, C. aurantium L., C. paradisi Macf, C. sinensis Osbeck and so on were not only rich in phenolic compounds, but their antioxidant capacities were higher than other genotypes, therefore they could be used furtherly, phenolics were the main contributors of antioxidant capacity of Chinese native citrus species. |
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