Studies On The Fungicidal Ingredients Of Psoralea Corylifolia L. And Its Formulations Preparation

In this dissertation,Psoralea corylifolia L.was selected as plant material through antifungal activity screening.The active ingredients in Psoralea corylifolia L.extract were systemically isolated and 5 components were achieved,and their fungicidal activities was firstly reported in this dissertation.The mechanism of action was also preliminarily studied. The optimized formulation of 0.4%Buguzhi emulsion and soluble was prepared,and 0.4% Buguzhi emulsion was applying in field.This research provides theoretical proofs for the development of Psoralea corylifolia L.as a botanical fungicide.1.Psoralea corylifolia L.was selected as target plants for further studies through antifungal tests on 105 herbal plant extracts.Spore germinating inhibition test,hypha growth inhibition test and potted plant test were used for the bio-activity evaluations.Test results demonstrated that Psoralea corylifolia L.extract showed＞50%hyphae growth inhibition against 15 pathogens at 1g/L.It has specific inhibition activities against Valsa mali Miygabe et Yamada.,Pyricularia grisea Sacc.,Colletotrichum orbiculare(Berk.et mont.),Fusarium graminearum Schw.,Colletotrichum coccodes(Wallr.)Hughes with EC50 values of 23.027mg/L,40.55mg/L,69.729mg/L,80.244 mg/L and 91.699mg/L respectively。2.An optimized preparation process of Psoralea corylifolia L.extract was get through single factor trials as follows:70%ethanol was selected as extracting solvent,the ratio between plant material and solvent was 1:5(w/v),extracted in room temperature for 3 h,and combine filtered solution for more than 2 times.Through test-tube test and circle filter paper method,the chemical components were preliminarily determined that phenols,flavones, lactones,coumarins,sterols terpenes and essential oils may exist in Psoralea corylifolia L. extract.3.The active ingredients in Psoralea corylifolia L.extract were systemically isolated and 5 components were achieved and identified as bakuchiol,bavachalcone,bavachin,bakuchicin, and psoralidin.Their fungicidal activity were tested against Valsa mali Miygabe et Yamada. and the result showed that these 5 compounds have good inhibition activity,with EC₅₀values of 6.117 mg/L,3.420 mg/L,6.144 mg/L,60.441 mg/L and 36.815 mg/L respectively,with EC₉₀values of 204.480mg,15.334mg/L,89.631mg/L,97.795mg/L,221.860 mg/L respectively.It suggested that bavachalcone and bavachin are the main active ingredients in Psoralea corylifolia L..4.Microscopic observations showed that Psoralea corylifolia L.extract has obvious effects on the hyphae morphorlogy of plant pathogens on PDA growth media.Deformed growth of hyphae of Valsa mali with agglomerated protoplasm,faint outlines and ramulose was induced.For Colletotrichum orbiculare,its hyphae was condensed and yielded a large number of cystids.In liquid culture condition,the inhibition on hyphal dry weight of Valsa mali was increased with the enhancement of test concentration and inhibition ratio was 98.3% under 80 mg/L after 3 hours treatment with Psoralea corylifolia L.extract.Tests on the cell wall formation related substrates and hydrolysis related enzymes in Valsa mali showed that after treatment with 50 mg/L Psoralea corylifolia L.extract for 3 hours,activities of chitinase andβ-1,3-glucanase were significantly increased to 3.62 and 9.98 folds of the check,resulted in the degradation of cell walls and the deformation and autolysis of hyphal cells.The content of soluble protein and reductive glucose kept at lower level than check resulted in the decrease of metabolism and growth inhibition.5.Effects of Psoralea corylifolia L.extract on the defensive enzymes on cucumber were studied and the results showed that activities of peroxidase(POD),polyphenol oxidase(PPO), phenylalanine ammonialyase(PAL)of cucumber leaves were increased to highest level after 7 to 9 days at 40 mg/L and 400 mg/L.Activities of chitinase achieved at peak level after 2 to 3 days and were 1.64 and 1.5 fold of check,then deceased gradually and resumed to normal level after 7 to 9 days.Forβ-l,3-glucanase,its activity increased to peak level after 2 to 5 days and was 2.02 and 1.34 folds of check,then decreased rapidly and resumed to normal level after 5 and 9 days.Generally Psoralea corylifolia L.extract may enhance the activities of chitinase andβ-l,3-glucanase in cucumber leaves,then induce the enhancement of activities of defensive enzymes.So it can be deduced that Psoralea corylifolia L.can induce the resistance of cucumber against the plant diseases.6.An optimized formulation of 0.4%Buguzhi emulsion(EW)was prepared as follows (w/w):Bavachalcone 0.4%,Triton-1600 7%,Tween-20 2%,Emulsifier S-20 1%, cyclohexanone 3%;ethylene glycol 5%and add water to 100%.An optimized formulation of 0.4%Buguzhi soluble(SL)was prepared as follows(w/w):Bavachalcone 0.4%,emulsifier 0201B 5%,emulsifier 0203B 3.3%,Triton-500 1.7%,water 10%,ethylene glycol 10%and add N,N-dimetylformamide to 100%。Quality assessment tests showed that these two formulations had good dispersibility,suspensibility storage properties.After stored under 54±2℃for 14 days,the degradation ratio of active ingredients in these two formulation were both less than 5%.Field try indicate that 0.4%Buguzhi emulsion have good control effect on Apple rot,scraping effect is better than cutting effect,scraping method should dilute 100 times when applying in field,cutting metod should dilute 50 times when applying in field.