| Subgenus Citrus is the most important part of the Citrus and it mainly includes Citrus medica?Citrus medica var.sarcodactylis,Citrus medica var.ethrog?,Citrus limon,Citrus aurantfolia,Citrus aurantium,Citrus sinensis,Citrus reticulate?Citrus retculate var.austera?,Citrus grandis,Citrus paradis,Citrus indica and Citrus tachibana.Sub.Citrus fruits contain a lot of polyphenols,which not only have good antioxidation and antifungal activity,but also have important research significance to the corresponding disease control of human body.At present,the studies on polyphenols of Sub.Citrus fruits mainly focused on the varieties of Citrus reticulate,Citrus limon,Citrus sinensis and Citrus grandis,etc.,which had less research on Citrus medica,Citrus aurantium,Citrus indica,and Citrus tachibana.This study took the peel of the twelve species of Sub.Citrus as objects,and optimized the extraction conditions of polyphenols.The contents of total phenol and total flavonoids in orange fruits were determined by ultraviolet spectrophotometer.Then,used high performance liquid chromatography?HPLC?in detecting various peel extractions of polyphenols.In addition,the antioxidant activities was evaluated by DPPH,FRAP and ABTS methods.The antifungal activities of twelve species of Sub.Citrus on the growth of Penicillium italicum,Penicillium digitatum and Colletorichun gloeosporioides were detected by the medium additive method.Finally,combined with the data analysis software to peel extractions of polyphenols and antioxidant,bacteriostatic action for correlation analysis to found out the main action factors of antioxidant and antifungal activity in Sub.Citrus.The main results were as follows:?1?The optimal conditions of the ultrasonic extraction process of polyphenols from Sub.Citrus were obtained as follows:100%methanol with 1 g:20 mL ratio of Sub.Citrus to solvent,extracting 30 minutes at 60?.?2?All of the twelve species of Sub.Citrus were rich in polyphenols and the total phenolic substance was range from?8.882±0.622?mg.g-11 DW to?52.241±2.148?mg.g-11 DW,the total flavonoid content was range from?15.389±0.302?mg.g-11 DW to?58.168±0.919?mg.g-11 DW.Phenolic acids mainly existed in the form of gallic acid and chlorogenic acid.Among them,the gallic acid?0.6143±0.1198 mg.g-11 DW?and chlorogenic acid?0.4765±0.0571 mg.g-11 DW?contents were highest in the extraction of Citrus tachibana.The main components of flavonoids were hesperidin,narirutin and diosmin.The content of hesperidin was the highest in Citrus reticulate var austera(51.3492±5.6819 mg.g-1 DW).The contents of narirutin(23.8087±2.7941 mg.g-1 DW)and diosmin(8.4432±1.0556 mg.g-1 DW)were the highest in Citrus aurantium.?3?All of the twelve species of Sub.Citrus had good antioxidant activity and the APC?antioxidant potency composite?composite index was range from 37.55%to100%.The comprehensive antioxidation ability of Citrus reticulate var austera was the strongest,followed by Citrus reticulate and the most weakest comprehensive antioxidant capacity was Citrus medica var.Sarcodactylis.?4?All of the twelve species of Sub.Citrus had good bacteriostatic effect on 3 kinds of pathogenic fungi?Penicillium italicum,Penicillium digitatum,Colletorichun gloeosporioides?.In the case of one single pathogenic fungi species,Citrus limon had the strongest inhibitory on Penicillium italicum?49.19±0.83%?,Citrus medica had the strongest inhibitory on Penicillium digitatum?35.23±1.12%?,and Citrus tachibana had the strongest inhibitory on Colletorichun gloeosporioides?32.74±1.23%?.As a whole,Citurs limon had the strongest overall resistance to the three pathogenic fungi?antifungal activity of composite index was 97.81%?,followed by Citrus tachibana?antifungal activity of composite index was 79.76%?,and Citrus medica var.sarcodactylis had the weakest overall resistance to the three pathogenic fungi?antifungal activity of composite index was 29.42%?.?5?The composition of the polyphenols in Sub.Citrus and the correlation analysis of antioxidant and antibacterial activity showed that different components of polyphenols had different antioxidation and antibacterial activity?P<0.05?.The main factors in the FRAP reaction system were chlorogenic acid?r=0.651?and tangeretin?r=0.595?.The main factors in DPPH reaction system were hesperidin?r=0.691?and total phenol?r=0.901?.The main factors in the ABTS reaction system were chlorogenic acid?r=0.673?,hesperidin?r=0.736?and total phenol?r=0.813?.The effects of gallic acid,chlorogenic acid,ferulic acid,eriodictyol and nobiletina had strong inhibitory effects on Colletorichun gloeosporioides,and eriodictyol also had strong inhibitory effects on Penicillium italicum. |
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