| Rosemary(Rosmarinus officinalis L.)is a kind of plant belonging to the genus Rosmarinus of the family Labiatae and native to Mediterranean coastal regions and now mainly has been cultivated with large area in Yunnan,Guizhou,Hainan in China recent years.Rosemary has been used as spices and for seasoning for table and pickled,smoked foods.Its components mainly include flavonoids,terpenoids,and essential oils.However,most of the existing reports only focus on the studies of several active components in rosemary,such as rosmarinic acid.This article focuses on study the components and antioxidant activities of rosemary flavonoids systematically,then guides its application as natural antioxidants in food.This study consists of four parts:(1)The optimal conditions for microwave-assisted extraction of flavonoids from rosemary established by using single factor experiments(consist of five factors including ethanol concentration,ratio of liquid to solid,microwave temperature,initial microwave power and extraction time)and response surface methodology were as follows:ethanol concentration 45%,ratio of liquid to solid 40:1(mL:g),microwave temperature 77℃,initial microwave power 500 W,and extraction time 7 min.The yield of total flavonoids was7.88%under these conditions.(2)The rosemary flavonoids were purified by D101 macroporous resin and the purification conditions were as follows:concentration of sample solution 1.0 mg/mL,pH value 4,flow 2 BV/h,elution agent(ethanol)concentration 50%.The purification effect was evaluated by HPLC method and the purity of flavonoids increased from 30%to 70%under these conditions,2.3 times purer than before.(3)Qualitative and quantitative analysis of rosemary flavonoids were carried out by using high performance liquid chromatography coupled with tandem mass spectrometry with electrospray ionizationand negative ion detection(HPLC-ESI-MS/MS).Based on the relative molecular weight,retention times and MS~2 fragmentation pattern compared with standard substances,twelve flavonoids were determined including gallocatechin,Geniposide,dihydrosyringin,luteolin-7-glucoside,luteolin-7-O-b-D-glucuronide,hesperidin,quercetin-3-O-glucuronide,rosmarinicacid,apigenin-7-O-glucoside,luteolin-5-O-glucuronide,luteolin-3’-O-glucuronide,and rosmanol.(4)The abilities of scavenging DPPH free radicals and OH free radicals of each component from rosemary flavonoids were evaluated by two off-line high performance liquid chromatography(HPLC)coupled with chemical methods.The results showed that rosmarinic acid had the strongest scavenging activities in 2,2-diphenyl-1-picrylhydrazyl(DPPH?)and hydroxyl free radicals(?OH),and the scavenging rate was up to 86.5%and83.9%,respectively,while other components had various scavenging activities in the two free radicals.Meanwhile,the cellular antioxidant activity of rosemary flavonoids was preliminarily evaluated by cell model.The results indicated that rosemary flavonoids with concentration ranges from 1 to 100μg/mL did not significantly affect the cell viability of human cervical cancer cells(Hela)and the ability of rosemary flavonoids in reducing the ROS in Hela was higher than rosmanol and lower than rosmarinic acid.However,cell viability reduced to 62.3%when the concentration increased to 1000μg/mL,which indicated that rosemary flavonoids had the ability in killing Hela.(5)Potassium-cyclodextrin metal organic frameworks(K-CD-MOF)inclusion complex of rosemary flavonoids(RF-K-CD-MOF)was prepared and the flavonoids inclusion rate of RF-K-CD-MOF was 87.9%.The result showed that thermal and acid-basic stabilities of RF-K-CD-MOF were better than rosemary flavonoids.Moreover,rosemary flavonoids and RF-K-CD-MOF were added to marinate meat to study the lipid oxidation behavior during processing,the results indicated that rosemary flavonoids exhibited lower peroxide value(POV)and malondialdehyde(MDA)content than that of the control,and the groups with RF-K-CD-MOF displayed better effect in inhibiting lipid oxidation. |
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