Extraction Of Flavonoids In Bamboo Leaves With Graphene Oxide-assisted Ethanol Reflux And Its Application In Cigarettes

Flavonoids in bamboo leaves have of many effects such as anti-free radicals, anti-aging, antioxidant and immunomodulatory. In present work, graphene oxide-assisted ethanol reflux extraction (GERE) was used to extract flavonoids in bamboo leaves, and extracts were used for cigarettes flavoring. The research provides a theoretical basis for developing a new natural tobacco spice.Firstly, the content of total flavonoids in bamboo leaves was determined using UV spectrophotometry, Al(NO3)3 colorimetry and AICl3 colorimetry, respectively. And the condition of AICl3 colorimetry was optimized. The results showed that the AICl3 colorimetry is simple, accurate and stable relatively. A good linear relationship was found at the Isoorientin content range of 0.0032-0.016mg/mL with R2 of 0.9996. The average recovery and RSD was 101.05% and 2.71%, respectively.Then, GERE was used to extract flavonoids in bamboo leaves. The parameters of GERE were optimized by the fractional factorial-response surface method, the optimal conditions were ethanol 80%(v/v), 17 mL/g ratio of liquid to solid, 1.5 mg GO/g dry raw material at 82? for 86minutes. Under optimized conditions, the yield of total flavonoids was 88.4%, about 10.6% higher than ethanol reflux extraction (ERE). SEM,FT-IR and XRD results revealed that GO can lead to the destruction of the cell wall,the reduction of the crystallinity and the grain sizes of cellulose, which improved the extraction rate of flavonoids in bamboo leaves.The sensory evaluation indicated that the bamboo leaves extracts could improve smoking quality, reduce the irritancy, and make tobacco smoke sweet and smooth.Among them, the volatile oils had only single effect, so its test quality was inferior to flavonoids. The extract obtained by GERE for improving tobacco flavor is better than that by ERE, and the resin separation has little effect on the cigarettes flavoring of the GERE extract. In addition, the flavonoids in P.heterocycla leaves from Lu'an and P.bambusoides leaves from Anqing performed well in cigarettes flavoring. The HPLC of bamboo leaves extracts indicated that there were variety flavonoids in P.heterocycla leaves from Lu'an, and P.bambusoides leaves from Anqing. However, the composition of extracts in P.viridis leaves from Lu,an was mainly Isoorientin and Orientin. The species and contents of flavonoids in bamboo leaves were well reserved during the process of resin purification. The results of pyrolysis showed that the major compounds in pyrolysis products were benzene and its homologues, polycyclic aromatic hydrocarbons and the minor compounds were acids and esters. The factors of flavonoids in bamboo leaves on cigarettes flavoring are ascribed to those phenols and higher fatty acid esters.GERE method improved the extraction rate of flavonoids in bamboo leaves, and its extracts performed better smoking quality of the cigarettes. So it is an efficient, green,novel method for extraction of flavonoids in bamboo leaves.