The Extraction And Separation Of Flavone In Hibiscus Manihot Flower And The Investgation Of Its Activities

Hibiscus manihot L is an annual or perennial herbage plant of malvaceous Abelmosk.It is widely cultivated in the domestic and the whole plant can be used as medicines.Hibiscus manihot flowers contain a plenty of bioactive components,among which the content of flavonoids is as high as 6%.Flavonoids have strong antioxidant activity.They can enhance antioxidant function in metabolism,have prominent functions in against anoxia of heart and brain,protect liver injury,and so on.Though there are abundant flavonoids in Hibiscus manihot flowers,few activities of the flavonoids have been reported.We extracted the total flavonoids from Hibiscus manihot flowers and the content was determined as high as 4.31% using 70% ethanol as solvent.Hibiscus manihot flower total flavonoids were separated with chloroform and methanol gradient elution?90:10-0:100?and the components were collected.According to the fluorescent UV color reaction,we identified the collect components with 2% nitric acid alcohol solution of aluminum.The results show that the flavonoids are washed out when the eluent chloroform: methanol for 80:20 and it is ran out when the eluent chloroform: methanol as 40:60.The total flavonoids in the Hibiscus manihot flower was extracted using 70% ethanol and the content of total flavonoids was measured.The total flavonoids of Hibiscus manihot was separated by using column chromatography on silica gel.The bacteriostatic activity and antioxidant activity of the Hibiscus manihot flower total flavonoids have been studied.Main results as follows:The antimicrobial activity of total flavonoids in Hibiscus manihot flower was investigated through paper diffusion method against the tested of Staphylococcus aureus,Escherichia coli,Bacillus subtilis,Bacillus cercus and Saccharomyces cerevisiae.The results show that the Hibiscus manihot flower total flavonoids plays a stronger antimicrobial activity against the tested bacterial than 70% ethyl alcohol and the Hibiscus manihot flower total flavonoids do not have antimicrobial activity to fungus such as yeast.The results of MIC of the four bacterial are: Escherichia coli 0.25 mg/mL,Bacillus cercus 0.25 mg/mL,Staphylococcus aureus 0.125 mg/mL,Bacillus subtilis 0.125 mg/mL.The total flavonoids stability to temperature,acid and ultraviolet were also studied.The results showed that the bacteriostatic activity is very stable to temperature and ultraviolet.It is strong antibacterial activity under acid condition,but when pH passed 8,the extract showed less of antibacterial activity.The antioxidation activities of the total flavonoids in Hibiscus manihot flower were studied inclduding scavening of?·OH?,DPPH,?O₂-·?and reducing capacity.The results showed that when solution concentration is as high as 180mg/L,the clearance rate to the?·OH?and DPPH is highest with the eluent from chloroform:methanol as 70:30,the clearance rate to the?·OH?reached 71.3%,the clearance rate to the DPPH reached 82.6%.The clearance rate to the?O₂-·?is 70.9% with the eluent chloroform: methanol as 80:20.