Study On The Chemical Composition And Biological Activity Of The Peel Of Wendan Pomelo From 10 Places In China

Pomelo is the fruit of Citrus maxima(Burm.)Merr,a plant in genus of Citrus(Rutaceae)and is widely cultivated in China.Wendan[C.maxima(Burm.)Merr.cv.Wentan]is one of the three major cultivated pomelo varieties in China.It is an important crop in Fujian,Zhejiang,Guangxi and other southern provinces.The annual output of Wentan pomelo accounts for about 49.7%of China's total pomelo production,leading to about 0.9-1.2 million tons of peels.To the best of our knowledge,the studies on the secondary metabolites in the peel of Wendan pomelo are not enough.In this thesis,total flavonoids from the peels of Wendan from 10 areas in China were prepared by alcohol extraction,and the volatile oils were prepared by steam distillation respectively.The chemical composition and biological activities of the flavonoids and essential oils of peels in 10 wendan samples were investigated respectively in detail for the first time.The results are summarized in the following paragraph:The yield of total flavonoids in 10 samples ranged from 11.08%to 16.12%;the content of total flavonoids ranged from 9.84 to 19.81 mg RT/gDW.A total of 24 compounds were detected from 10 samples by liquid chromatography-mass spectrometry.Moreover,21 compounds were identified by mass spectrometry database search,literature data comparison,as well as NMR spectral analysis.Among them,Genipin-?-gentiobioside(CPF 12),Dimethylallyl-methoxycoumarin(CPF22)and Meranzin hydrate(CPF 16)were reported in pomelo for the first time.While Apiginin-O-(deoxyhexosyl)hexoside(CPF8),Hydroxy-methoxy(iso)flavone-O-hexoside(CPF10),Meranzin hydrate(CPF 16),Lucenin-24'-methylether(CPF 11),Genipin-?-gentiobioside(CPF F 12),Dimethylallyl-methoxycoumarin(CPF22),and Diosmetin-7-O-rutino side(CPF23)were reported for the first time in Wendan pomelo.The common compounds in 10 samples were chlorogenic acid(CPF6),rutin(CPF7),narirutin(CPF13),hesperidin(CPF14),neohesperidin(CPF15)and meranzin hydrate(CPF 16).The relative content of rutin(0.08-1.23 mgNA/gDW)?naringin(0.17-2.45 mgNA/gDW),hesperidin(0.11-2.22 mgHE/gDW)?neohesperidin(0.05-0.60 mg NA/gDW)and Meranzin hydrate(3-4.5 mgMH/gDW)were determined in the 10 samples.DPPH,ABTS and FRAP experiments were used to evaluate the samples antioxidant activity,while Fujian Putian(WF1)and Zhejiang Taizhou(WF7)exhibited antioxidant capacity.In DPPH test,WF1 showed SC5O value at 1.01 mg/mL,and WF7 showed SC50 value at 0.59 mg/mL.In the ABTS test,WF1 showed 67.65?mol TE/g,and WF7 showed 60.62 ?molTE/g.In FRAP test,WF1 showed 95.10 ?mol Fe2+/g,and WF7 showed 97.06 ?mol Fe2+/g.In the minimum inhibitory concentration(MIC)experiment,Putian WF1(MIC=31.25-125 ?g/mL),Zhangzhou WF2(MIC=125-500 ?g/mL),Nanping WF4(MIC=125-500?g/mL),and Zhejiang WF7(MIC=31.25-125 ?g/mL)showed good antibacterial activity.In the cytotoxicity experiment,Putian WF1(IC50=44.25-72.68 ?g/mL),Zhangzhou WF2(IC50=84.61-97.3 5 ?g/mL),and Taizhou WF7(IC50=43.39-75.278 ?g/mL)exhibited considerible inhibitory activity on humans cervical cancer,human breast cancer and human liver cancer cells respectively.In the ?-glucosidase inhibitition experiment,Putian WF1,Zhangzhou WF2 and Nanping sample WF4 showed inhibitory activity,with their IC50 values were 4.67mg/mL,7.99mg/mL and 6.44mg/mL respectively.The yield of essential oil from the 10 samples ranged from 0.69%to 1.45%.A total of 54 compounds were detected from the samples by gas chromatograohy-mass spectrometry,while the detection rate ranged detection from 95.48%to 98.49%.Then a total of 38 compounds were identified,and the abundant and characteristic compounds were?-myrcene(CP4,19.16%-27.95%),d-limonene(CP8,51.06%-57.77%)and nocardione(CP52,2.82%-6.16%).Based on the chemical composition,the ten samples were divided into three clusters by principal component analysis and cluster analysis.In detail,Putian Fujian WE1 and Zhejiang Taizhou WE7 were in cluster ?,Nanping Fujian WE4,Meizhou WE10,Ganzhou WE5,Guangxi Yulin WE9,Fujian Quanzhou WE3 and Fujian Zhangzhou WE2 were in cluster ?,whereas,Zhejiang Jiaxing WE8 and Jiangsu Xuzhou WE6 were in cluster ?.Furthermore,WE1(SC50=4.72 mg/mL)and WE7(SC50=5.67 mg/mL)showed free radical scavenging ability in DPPH test.In the experiment of minimum antibacterial activity,WE1 and WE7 showed good inhibitory activity,with the MIC values less than 625 ?g/mL.The results of cytotoxic activity showed that WE1(IC50=37.45 ?g/mL),WE2(IC50=87.55?g/mL),WE5(IC50=92.71?g/mL),and WE7(IC50=20.69 ?g/mL)with good inhibition effect on human liver cancer cells.Meanwhile,all of them showed good inhibitory activity on human cervical cancer cells with IC50 values at 43.13 ?g/mL(WE1),99.76 ?g/mL(WE2),and 85.69?g/mL(WE5)and 66.24 ?g/mL(WE7)respectively.The data in the thesis showed that the flavonoids and essential oils in the Wendan peels had good biological activities,showing the potential of being developed into natural antioxidants,antibacterial agents and food additives.The results of this thesis provide systematic and detailed data support for the further development and utilization of the Wendan peel in the food industrial products,such as spices,natural antioxidants,antibacterial agents and functional foods,which laid a scientific foundation for the utilization of natural plant resources in China.