Study On Extraction And Bacteriostasis Of Ginkgo Acid From Ginkgo Biloba Testa

In recent years,Ginkgo biloba testa extract and its related preparations are one of the most popular natural plant preparations.Moreover,Ginkgolic acid shows good antibacterial activity as an important bioactive ingredient in Ginkgo biloba testa.However which has not been fully utilized because of its sensitization toxicity.At present,the bacteriostatic study about Ginkgolic acid only focuses on antibacterial activity,and its antibacterial mechanism has not been further studied.The aim of the paper is mainly about extraction and purification of ginkgolic acid from Ginkgo biloba testa,and bacteriostatic activity and antibacterial mechanism of ginkgolic acid on foodborne bacteria and epiphyte.Then resources of Ginkgo biloba will be more developed further.The results were as follows:1.Ginkgolic acid was extracted from Ginkgo biloba testa and extracted by solvent extraction.Then ginkgolic acid was purified by macroporous resin and silica gel.After purification,the purity of ginkgolic acid was increased from 20.07% to 69.18%.2.There were 5 main peaks in Ginkgolic acid analysis by HPLC,They were C13:0,C15:1,C17:2,C15:0 and C17:1.Among them,the content of C15:1 is the highest.Results of infrared spectrum showed that Ginkgolic acid contained phenolic hydroxyl,-CH3,-C=O,benzene and other functional groups.3.The inhibitory effects of Ginkgolic acid on Salmonella,Escherichia coli,Listeria monocytogenes,Vibrio parahaemolyticus,S.aureus,Sarcina and Bacillus subtilis.Ginkgolic acid showed a strong inhibitory effect on Gram-positive bacteria such as S.aureus,Sarcina and Bacillus subtilis.By measuring the diameter of bacteriostasis and minimum inhibitory concentration,the inhibition ability of S.aureus was the strongest among the test strains,the diameter of bacteriostasis circle was 12.8± 0.15 mm,and the minimum inhibitory concentration was 31.25 μg/m L.4.Ginkgolic acid can increase the conductivity of S.aureus bacteria and cause a large number of protein and nucleic acid leaks out of thebacterium.Which indicated that ginkgolic acid acted on the cell membrane of S.aureus,increased its cell membrane permeability and destroyed the cell membrane integrity.5.Ginkgolic acid had different inhibitory effects on pathogenic fungi Alternaria,Nigrospora sphaerica and P.expansum.It alsoexhibited the strongest inhibitory effect on Alternaria and Nigrospora sphaerica.At a concentration of 5mg/m L,the inhibition rate of Nigrospora sphaerica and Alternaria was 65.82%and 56.96% respectively.6.Results of inhibitory mechanism of ginkgolic acid on Nigrospora sphaerica were as follows:(1)Ginkgo acid had the ability to cleavage the cell membrane,which made the cell membrane permeabilityhigher and the electrical conductivity of the mycelium rise,damagedcell membrane damage and made the mycelial protein leak out.(2)Ginkgolic acid reduced the activity of SOD and CAT in the mycelium of Nigrospora sphaerica,and weakened the protective effect of the resistant enzyme to the mycelium of the Nigrospora sphaerica,which showed the inhibition effect of ginkgo acid on Nigrospora sphaerica.7.The results of leaf puncture test were as follows: the order according to the degree of leaf disease was: Nigrospora sphaerica group > Ginkgolic acid bacteriostasis group > Blank group > Ginkgolic acid group.It indicated that Ginkgo acid can effectively prevent and control plant diseases from Nigrospora sphaerica.