Studies On The Antifungal Effects And Chemical Constituents Of The Extracts Of Bauhinia Purpurea L.Barks

Bauhinia purpurea L.,Bauhinia family,is a Chinese herbal medicine used by people.the plant resources and bioactive ingredients are rich.On the basis of previous studies,the growth rate method,modem chromatography and spectroscopy methods were used to study the antifungal active ingredients in the barks of Bauhinia purpurea L.in this paper.The main results described are as following:1.Bauhinia purpurea L.was extracted with 70%ethyl alcohol,the extract was extracted with different polar organic solvents and to give the ethyl acetate extract and the n-butyl alcohol extract.the antifungal activities of these extracts against 18 common pathogenic fungis such as Alternaria solani,Botrytis cinerea,and Colletotrichum gloeosporioides had been tested.The results showed that the 70%ethyl alcohol extract,the ethyl acetate extract and the n-butyl alcohol extract of Bauhinia purpurea L.barks all had antifungal effects at the concentration of 2 mg mL-1.The antifungal effect of the ethyl acetate extract was the best and the inhibition rates of this extract were over 60.00%against Alternaria solani,FusaHum graminearum Sehw,Gliocladium catenulatum,Helminthosporium maydis,Rhizoctoniasolani Kuehn and Valsa malimiyabe.The result of toxicity test showed that the EC50 value of the ethyl acetate extract against Alternaria solani,FusaHum graminearum Sehw,Gliocladium catenulatum,Helminthosporium maydis,Rhizoctoniasolani Kuehn and Valsa malimiyabe were 4.011,1.266,2.589,1.859,2.058 and 2.482 mg·mL-1,respectively.2.17 compounds were isolated from the ethyl acetate extract of Bauhinia purpurea L.barks by common column chromatographies and preparation of high performance liquid chromatography.By using spectroscopic methods,the structures of 17 compounds were identified as7S,8R,8R’-(-)5-methoxylariciresinol 4’-O-β-D-glucopyranoside(1),(6S,9S)-roseoside(2),(6R,9R)-3-O-a-ionol-β-D-glucopyranside(3),(6R,9S)-3-O-α-ionol-β-glucopyranside(4),(+)-dehydrovomifoliol(5),loliolide(6),betulinic acid(7),3,4,5-trimethoxy-phenyl-O-β-D-glucopyranside(8),phenyl-O-β-D-glucopyranoside(9),methyl-2-O-β-D-glucopyransyl-benzoaye(10),benzyl-α-rhamnopyranosyl-(1→6)-β-D-glucopyranoside(11),luteolin(12),quercitrin(13),3-(4-hydroxy-3-methoxy-)-phenyl-1,2-propandiol(14),benzoic acid-4-(hydroxymethyl)-methyl ester(15),dibutyl phthalate(16),diisobutyl phthalate(17).Except for compounds betulinic acid(7),quercitrin(13)and 3-(4-hydroxy-3-methoxy-)-phenyl-1,2-propandiol(14),the other 14 compounds were for the first time isolated from Bauhinia family.3.The antifungal effects of compounds 1～17 against Alternaria solani,FusaHum graminearum Sehw,Gliocladium catenulatum,Helminthosporium maydis,Rhizoctoniasolani Kuehn and Valsa malimiyabe had been tested.The result showed that compounds 7S,8R,8R’-(-)5-methoxylariciresinol 4’-O-β-D-glucopyranoside(1),loliolide(6),methyl-2-O-β-D-glucopyransylbenzoaye(10)and quercitrin(13)exhibited significant inhibiting effect against 6 pathogenic fungis,with inhibitory rates between 32.08%～69.31%at the concentration of 0.02 mg·mL-1.The antifungal effect of compound methyl-2-O-β-D-glucopyran-sylbenzoaye(10)was the best,the inhibition rate of it against Alternaria solani,FusaHum graminearum Sehw,Gliocladium catenulatum,Helminthosporium maydis,Rhizoctoniasolani Kuehn and Valsa malimiyabe were 67.12%,68.37%,54.69%,54.29%,50.24%and 69.31%,respectively.Preliminary antifungal mechanism test results showed that the compound 7S,8R,8R’-(-)5-methoxylariciresinol 4’-O-β-D-glucopyra-noside(1)made a difference to the mycelia shapes of FusaHum graminearum Sehw and Valsa malimiyabe under the microscope,compared to control groups,the mycelias of treatment groups were swelled,disorderly arranged and fractured.