Extraction Of Antibacterial Active Ingredients From The Leaves Of Psoralea Corylifolia And Preliminary Study On Its Wood Preservative Functio

Wood preservative treatment is an important means to alleviate the contradiction between supply and demand of wood at home and abroad.In view of the fact that the environmental protection of wood preservatives commonly used in the market has been questioned,the development of environmentally friendly and efficient new wood preservatives has become a hot spot in the field of wood protection research.In order to explore new and potential plant preservatives,the antibacterial activities of 10 plant extracts against 4 kinds of wood rot fungi were compared by mycelial growth rate method firstly,and it was determined that the leaves of Toddalia asiatica had better antibacterial effect.After that,the extraction solvent suitable for the leaves of Toddalia asiatica was selected,and the extraction process was optimized by single factor design and orthogonal test.The toxicity and EC₅₀value to the mycelium growth of wood rot fungus were determined,and the chemical composition of antibacterial active components was analyzed by GC/MS.Finally,the extracts of the leaves were prepared as preservatives with different concentrations,and the test materials of Pinus massoniana and Populus tomentosa were treated by vacuum immersion to explore their corrosion resistance.The main results are as follows:（1）At the test concentration of 20 mg/m L,the 50%ethanol extracts from 10 plants leaves had different inhibitory effects on white rot fungi and brown rot fungi.When the colonies were cultured for 7 days,the extracts of Toddalia asiatica and Cinnamomum camphora had strong inhibition against 4 kinds of wood decay fungi.And the bacteriostatic of effect Toddalia asiatica was better than that of Cinnamomum camphora,the bacteriostatic rate were higher than 70%.Cluster analysis also confirmed that the Toddalia asiatica was an efficient and broad-spectrum antibacterial plant,so the leaves of Toddalia asiatica were determined as the further research object.（2）There were significant differences in the extraction rate,colors and properties of the four solvent extracts extracted from the leaves of Toddalia asiatica by water,methanol,70%ethanol and absolute ethanol.The extraction rate was positively correlated with the polarity of the solvent.The water extracts had no inhibitory effect against four kinds of wood rot fungi.The total inhibitory effects of the other three extracts against wood rot fungi was anhydrous ethanol extracts,methanol extracts,70%ethanol extract,and the extracts of anhydrous ethanol had the best antibacterial effect.（3）Using anhydrous ethanol as solvent,the optimum technological parameters of water bath reflux extraction of antibacterial active components from Toddalia asiatica were as follows:liquid/solid ratio was 20:1 m L/g,extraction time was 110 min,extraction temperature was 60℃,and the extraction rate was 8.27%.（4）The virulence regression analysis of the absolute ethanol extracts from Toddalia asiatica found that with the increase of the concentration of the extracts,the inhibitory effect on four kinds of wood decay bacteria increased significantly.The EC₅₀values of the extracts on four kinds of wood decay bacteria from small to large were as follows:Phanerochaete chrysosporium<Gloeophyllum trabeum<Trametes versicolor<Poria vaporaria,the values were 2.475,2.866,2.953 and 3.481 mg/ml respectively.（5）Forty compounds of anhydrous ethanol extract from the Toddalia asiatica were identified by GC/MC analysis.The main monomer compounds and their contents were Scopoletin（37.97%）,Escoparone（11.61%）,Vitamin E（8.65%）,Spinacen（4.81%）,Prangenin（4.29%）,α-Amyrin（4.11%）,Heraclenin（3.86%）,β-Sitosterol（3.20%）,Oxypeucedanin（2.61%）,β-Caryophyllene（2.36%）,etc.The main antibacterial substances were scopoletin,Escoparone and other coumarin compounds probably.（6）The corrosion resistance of treated wood was tested with Gloeophyllum trabeum and Poria vaporaria.The results showed that when the concentration of ethanol extracts was 80mg/ml,the treated wood of Pinus massoniana could reach grade I that was the strong corrosion resistance,while the sapwood of Populus tomentosa could reached grade I when the concentration of extracts was 100 mg/ml.In summary,this paper explored the extraction process,virulence and chemical composition of antibacterial active components from the leaves of Toddalia asiatica,and preliminarily explored its application potential in wood preservation.The result could provided basic data reference for the preparation of Toddalia asiatica derived wood preservatives,which was expected to improve the utilization rate of leaf resources of Toddalia asiatica.