Extraction Of Gannan Navel Orange Essential Oil And Its Antibacterial And Anticancer Activities

Citrus essential oil was an important food additives and fragrance materials and widely used in food,beverage and daily chemical products.In addition,citrus essential oil has various functional effects such as bacteriostatic,anti-inflammatory,analgesic,anti-oxidation and anti-cancer activities,and its research and development as a natural active substance has received wide attention.Gannan is China's largest navel orange industry,Newhall navel orange is the main cultivar in Ganan.Gannanzao is an early-maturing variety selected from the Newhall navel orange bud,which has excellent quality.In this paper,the composition and characteristics of essential oil components in different organs of Newhall and Gannanzao navel orange were studied.We optimized the hydrodistillation conditions for extracting essential oil from Gannan navel orange peel by response surface design and explored its antibacterial and anticancer activities.Our main research results were as follows:1.A total of 72 constituents were identified on the essential oils of peel,leaf and flower of Newhall and Gannanzao navel orange.27,44 and 39 compounds were identified in peel,leaf and flower essential oil of Newhall navel orange,respectively;38,39 and 42 compounds were identified in peel,leaf and flower essential oil of Gannanzao navel orange,respectively.Limonene was the prominent component of the peel oil of both oranges,accounting for 81.62% and 88.07% of the total composition,respectively.There were no dominant components in the leaf and flower essential oils.Sabinene,limonene,linalool,and citronellal were abundant components of leaf essential oils.Sabinene,linalool,and nerolidol were main components in flower essential oils.The components of the same organs of these two navel oranges showed certain similarities,but some differences in content with different organs.2.The essential oil of Gannanzao orange peel(GOEO)was extracted by hydrodistillation,and the extraction conditions were optimized by Box–Behnken response surface methodology.Three important factors were selected: liquid material ratio,sodium chloride concentration and distillation time.The results of single factor test and response surface design optimization showed that three factors had a highly significant effect on the yield of GOEO.The distillation time had the greatest influence on the response value of the yield,followed by NaCl concentration and the liquid material ratio.The optimal extraction conditions were as follows: liquid material ratio of 8.4:1(mL/g),sodium chloride concentration of 5.3%,and distillation time of 3.5 h,and the extraction rate was 2.14% under this condition.3.The antibacterial activity of Gannan navel orange essential oil and several individual components was studied.Both essential oils and some of individual constituents showed good antimicrobial activity on Saccharomyces cerevisiae,Escherichia coli,Staphylococcus aureus,and Bacillus subtilis,and the minimum inhibitory concentration were 0.20~15.48 ?L/mL.After heat treatment in 25~100?,the antibacterial activity of essential oil has no significant difference on Saccharomyces cerevisiae,Escherichia coli and Staphylococcus aureus.However,the antibacterial activity decreased after treatment at 121?.The essential oil showed less inhibitory activity against Bacillus subtilis after treatment at 100? and 121?.The pH value of the culture medium has a great influence on the antibacterial activity of the essential oil.When the pH value was 7.0,the antibacterial activity was the highest.4.The Cell Counting Kit-8 assay showed that Gannan navel orange peel essential oil had good dose-dependent inhibition effect on the proliferation of HepG2 hepatoma cells and HCT116 colorectal cancer cells.When the concentration of the essential oil was 0.6 ?L/mL or higher,the viability rate of both cancer cells became lower than 15.0%.The transwell assay indicated the essential oil can inhibit migration of both cancer cells at the concentration of 0.3 ?L/mL.In short,Gannan navel orange essential oils were a kind of natural product with high value.The research on the development and utilization of Gannan navel orange essential oils were not only conducive to improving the industrial chain and raising the value of Gannan navel orange,but also provide scientific reference and theoretical basis for the identification,quality evaluation of the navel orange variety and the development of novel antimicrobial and anticancer agents from navel orange essential oil.