Optimization Of Extraction Technology Of Crude Extract Of Schisandra Chinensis(Turcz.) Baill And Its Inhibitory Effect On Pathogenic Bacteria Of Three Cucurbitacae Vegetables

Schisandra chinensis（Turcz.）Baill.is a deciduous woody vine of Magnoliaceae.As a medicinal plant,it is mostly distributed in Liaoning,Heilongjiang,Jilin,Ningxia and other places.Its fruit,stem and root can be used as medicine,and it has the functions of astringing lung and nourishing kidney,promoting salivation and arresting sweating,and relieving diarrhea and sweating.Fructus schisandrae L.leaves and fruits can also be extracted from aromatic oil and fatty oil by pressing,which can also be used as industrial raw materials and lubricating oil.Yanbian Prefecture of Jilin Province is located at the foot of Changbai Mountain.Due to the rich resources of Schisandra chinensis,there are a large number of planting bases and retail investors in Dunhua,Antu and other counties and cities,and the relevant county and municipal governments have also included the exhibition of Chinese medicinal materials into the regional economic key projects,but its intensive and deep processing needs to be extended.With the continuous expansion of watermelon,muskmelon,cucumber and other cucurbits in the open and protected fields,the occurrence and damage degree of various diseases of cucurbits are rising,and there are also new diseases,which have increasingly serious impact on the yield and quality of cucurbits.The high-dose and high-frequency chemical control in the production also leads to the problems of drug resistance and pesticide residues.Therefore,it is urgent to study botanical fungicides against cucurbits diseases.In this paper,based on the above outstanding problems,the extraction process of crude extract of Schisandra chinensis was optimized by response surface methodology,and the inhibitory effects of crude extract of Schisandra chinensis on acidophagocytes,Pseudomonas watermelon and bacterial keratosis of cucumber were studied.The results are as follows:1.Single factor random block design was adopted to study the effects of four factors on the extraction yield of crude extract of Schisandra chinensis.The optimal single factor extraction conditions were as follows:ethanol volume fraction 67%,liquid/solid ratio 23:1 ml/g,ultrasonic extraction time 56min,ultrasonic extraction temperature 46℃.2.The mathematical model and regression equation of the interaction between ethanol volume fraction,liquid-solid ratio,ultrasonic extraction time,ultrasonic extraction temperature and extraction rate were established.（1）Coding equation of extraction rate of crude extract of Schisandra chinensis:Y_A=13.75-1.02X₁+0.57X₂+0.4X₃-0.043X₄+0.22X₁X ₂-0.81X₁X ₃-1.27X₁X₄+2.50X₂X ₃+0.26X₂X ₄+0.21X₃ X₄-1.48X₁ ²-1.43X₂ ²-2.20X₃ ²-1.42X₄²（2）Actual equation for true value of crude extract of Schisandra chinensis:Y_B=-189.04529+2.94534X₁-1.01907X₂+2.43757X₃+1.99417X₄+0.0022X₁X₂-0.008.15X₁X ₃-0.012675X₁X ₄+0.025X₂X ₃+0.002625X₂X ₄+0.002125X₃X₄-0.014803X₁ ²-0.014278X₂ ²-0.022028X₃ ²-0.014228X₄²3.The optimal extraction parameters were as follows:ethanol volume fraction 69%,liquid-solid ratio 27.6:1 ml/g,ultrasonic extraction temperature 49℃,and ultrasonic extraction time 55 min.Under these conditions,the maximum extraction rate was expected to be 14.41%.After five validation tests,the average extraction rate was 14.06%,and the reliability reached97.53%.The effect of each factor on the extraction rate from high to low was as follows:ethanol volume fraction>liquid ratio>ultrasonic extraction temperature>ultrasonic extraction time.4.The inhibitory effect,effective inhibitory medium concentration(EC₅₀)and minimum inhibitory concentration（MIC）of crude extracts of Schisandrae chinensis against three kinds of cucurbits pathogenic bacteria were measured by AGAR plate diffusion method and plate coating method.At 36h,the inhibitory rates of 100mg/ml Schisandrae chinensis extract against acid phagocytes,Pseudomonas watermelon and bacterial keratosis of cucumber were 44.04%,55.94%and 60.84%,respectively.The EC₅₀ and MIC of the three pathogens were 136.87mg/ml,71.03mg/ml and 46.56mg/ml,respectively.25mg/ml,12.5mg/ml,1.563mg/ml.In the indoor inoculation test of cucumber bacterial keratosis,the control effect of crude extract of Schisandra chinensis with the concentration of 2EC₅₀ or above could reach more than 50%,and there was a high concentration of high control effect,low concentration of low control effect.5.The crude extract of Schisandra chinensis had the best bacteriostasis effect on cucumber bacterial keratosis.By measuring the indoor control effect,peroxidase（POD）activity and superoxide dismutase（SOD）activity,it was found that the crude extract of Schisandra chinensis had certain prevention and control effect on cucumber bacterial keratosis.In the laboratory inoculation experiment on the control effect of cucumber bacterial keratosis,the phenomenon of high concentration and low concentration had high control effect,when the crude extract of Schisandrae chinensis reached 2EC₅₀（93.12mg/ml）or above,the control effect was more than54.08%.The analysis of enzyme activity showed that in the range of this experiment,the activities of POD and SOD were significantly increased under different concentrations of crude extract of Schisandra chinensis,and there was a positive correlation between the activities of POD and SOD and the disease resistance.