Study Of Plant-derived Antibacterial Agent For Ginkgo Biloba Exocarp

Ginkgo biloba L.has high scientific research and ornamental value.In recent decades,the medicinal value of Ginkgo biloba has become a hot topic in the field of medicine worldwide.Ginkgo biloba exocarp contains a large number of active ingredients,with antiinflammatory,anti-allergic,antitumor,insecticidal and antibacterial pharmacological effects.In this study,Ginkgo biloba exocarp(Zhong nanlinl)was used as the experimental material to optimize the combined extraction technology of total ginkgo acid and Ginkgo biloba biflavones as the active ingredients in Ginkgo biloba exocarp;the extracts of Ginkgo biloba exocarp extracts were separated,and the different active ingredients were subjected to plant pathogens inhibition experiments;the components with good bacterial inhibition effects were selected through the screening of green solvents and emulsifiers to prepare botanical antimicrobial agent of emulsifiable concentrate.The main results are as follows.(1)The optimal technology for the combined extraction of total Ginkgo biloba acids and biflavones from the Ginkgo biloba exocarp:90%ethanol,material-to-liquid ratio(g/mL)1:20,time 40 minutes,temperature 40℃,and extraction three times.The total ginkgolic acids extraction rate is 98.41 mg/g and the biflavones extraction rate is 285.22 μg/g,and the extraction rate of ginkgetin,isoginkgetin and sciadopitysin in ginkgo biloba biflavones are 79.48 μg/g,65.54 μg/g and 141.20 μg/g,respectively.(2)Extraction and separation of different components of Ginkgo biloba exocarp:5.5 g of Ginkgo biloba extract(S1)could be extracted from 10 g of dried Ginkgo biloba exocarp,and then the components of Ginkgo biloba exocarp extract were extracted and separated according to different physicochemical properties.5.5 g of Ginkgo biloba exocarp extract(S1)could be extracted and separated to obtain 3.6 g of aqueous phase A(S2),1.9 g of organic phase(S3),0.3 g of solid phase(S4),1.2 g of petroleum ether phase(S5)and 0.4 g of aqueous phase B(S6),respectively.(3)Antibacterial experiment of different components of Ginkgo biloba exocarp extracts:In the bacterial inhibition experiments,Si,S3 and S5 showed inhibition activity against Staphylococcus aureus and Pseudomonas aeruginosa,and the inhibition effect of S1,S3,S5 and total ginkgo acid standard solution at the concentration of lmg/mL is moderately sensitive against Staphylococcus aureus and Pseudomonas aeruginosa.For Pseudomonas aeruginosa and Staphylococcus aureus,the minimum inhibitory and bactericidal concentrations were 1mg/ml and 2mg/ml for S1,0.5mg/ml and 1mg/ml for S3,and 0.25mg/ml and 0.5mg/ml for S5.In the fungal inhibition experiment,5mg/mLS5 showed 44.16%inhibition against Streptomyces aegypti,and 10mg/mLS5 showed 60%inhibition against Streptomyces aegypti,S5 has good inhibition activity against Streptomyces aegypti,and the other components have no significant inhibition effect on the selected fungi.The content of ginkgo acid in S5 was 55.90%.The content of biflavones in S5 was detected to be very low and negligible,and(4)The optimum formulation of botanical antimicrobial agent of emulsifiable concentrate:petroleum ether fraction(S5)obtained from the separation of Ginkgo biloba exocarp extract as raw material,methyl oleate as solvent,BDS-Ca and 600#as emulsifier.The formulation was 3.5%S5,5%BDS-Ca,2%600#and 89.5%methyl oleate.(5)Botanical antimicrobial agent of emulsifiable concentrate antibacterial effect:the minimum inhibitory concentration and the minimum bactericidal concentration of the emulsifiable concentrate diluted 100 times and 50 times,respectively.In the experiment of tobacco leaf infection inhibition,Pseudomonas solanacearum as indicator bacteria,the pathogenic bacteria group had the largest degree of damage,followed by the blank group,the third was the emulsified concentrate diluted 100 times sterile group and diluted 50 times sterile group,and finally the emulsified concentrate diluted 100 times antibacterial group and the emulsified concentrate diluted 50 times antibacterial group.Both emulsified concentrate diluted 100 times and 50 times have antibacterial activity on Pseudomonas aeruginosa,and the latter have better antibacterial activity.