采用多重柱层析和重结晶的方法从甘草（Glycyrrhiza uralensis Fisch.）根中提取和分离6个黄酮类化合物，并通过结构修饰获得3个乙酰化衍生物，然后使用核磁共振和旋光技术进行结构鉴定；在此基础上，分别采用菌丝生长速率法和比浊法测定9个化合物在10 μg·mL^-1时对植物病原真菌和细菌的抑制率，并进一步测定了具有抑菌活性化合物的EC₅₀（有效中浓度）和EC₉₀（抑制率90%时的化合物浓度）值。结果表明：甘草根中6个黄酮类化合物及3个乙酰化衍生物分别为4′-O-甲基光甘草定、hispaglabridin B、光甘草定、甘草素、异甘草素、甘草苷、4，4′-O-二乙酰基异甘草素、4-O-乙酰基异甘草素和4′-O-乙酰基甘草素。在10 μg·mL^-1时，4′-O-甲基光甘草定、hispaglabridin B和光甘草定对大部分供试病原菌的抑制率较高，异甘草素对水稻白叶枯病菌（Xanthomonas oryzae pv. oryzae）的抑制率达到76.25%，而4，4′-O-二乙酰基异甘草素和4-O-乙酰基异甘草素对部分病原菌的抑制率高于30.00%。4′-O-甲基光甘草定对油菜菌核病菌（Sclerotinia sclerotiorum）、黄瓜灰霉病菌（Botrytis cinerea）和稻瘟病菌（Magnaporthe oryzae）的EC50值均小于10.00 μg·mL^-1，对黄瓜灰霉病菌的EC50和EC90值显著（P＜0.05）低于对照药剂甲基硫菌灵，对水稻纹枯病菌（Rhizoctonia solani）的EC₅₀和EC₉₀值与甲基硫菌灵总体上无显著差异。Hispaglabridin B对黄瓜灰霉病菌的EC₅₀和EC₉₀值显著低于甲基硫菌灵。光甘草定的抑菌活性最强，除了对枸杞炭疽病菌（Colletotrichum gloeosporioides）的EC₅₀值为48.90 μg·mL^-1外，对其他供试病原菌的EC₅₀值均小于10.00 μg·mL^-1，并且对水稻纹枯病菌、香蕉枯萎病菌（Fusarium oxysporum）、黄瓜灰霉病菌和小麦赤霉病菌（Fusarium graminearum）的EC₅₀和EC₉₀值总体上显著低于甲基硫菌灵。异甘草素对水稻白叶枯病菌的EC50值仅为2.98 μg·mL^-1，与对照药剂噻枯唑无显著差异。综上所述，4′-O-甲基光甘草定、hispaglabridin B和光甘草定具有广谱抑菌活性，可作为新型生物农药先导化合物进行开发；异甘草素对水稻白叶枯病菌具有较高的抑菌活性，可作为先导化合物开发细菌病害防治药剂。

 Six flavonoids were extracted and isolated from root of Glycyrrhiza uralensis Fisch. by using multi-column chromatography and recrystallization methods， three acetyl derivatives were obtained by structural modification， and then nuclear magnetic resonance and optical rotation technology were employed to confirm their structures； on the basis， inhibition rates of nine compounds at 10 μg·mL^-1 against plant-pathogenic fungi and bacteria were determined by using mycelial growth rate method and turbidity method， and EC₅₀（median effective concentration） and EC₉₀（compound concentration at the inhibition rate of 90%） values of compounds with anti-microbial activities were further assayed. The results show that six flavonoids isolated from root of G. uralensis and three acetyl derivatives are 4′-O-methylglabridin， hispaglabridin B， glabridin， liquiritigenin， isoliquiritigenin， liquiritin， 4，4′-O-diacetylisoliquiritigenin， 4-O-acetylisoliquiritigenin， and 4′-O-acetylliquiritigenin. At 10 μg·mL-1， 4′-O-methylglabridin， hispaglabridin B， and glabridin exhibit high inhibition rates against most test pathogens， inhibition rate of isoliquiritigenin against Xanthomonas oryzae pv. oryzae reaches 76.25%， while those of 4，4′-O-diacetylisoliquiritigenin and 4-O-acetylisoliquiritigenin against some pathogens are greater than 30.00%. The EC₅₀ values of 4′-O-methylglabridin against Sclerotinia sclerotiorum， Botrytis cinerea， and Magnaporthe oryzae are all smaller than 10.00 μg·mL^-1， and its EC₅₀ and EC₉₀ values against B. cinerea are significantly （P<0.05） lower than those of control fungicide thiophanate-methyl， but those against Rhizoctonia solani are not significantly different from those of thiophanate-methyl in general. The EC₅₀ and EC₉₀ values of hispaglabridin B against B. cinerea are significantly lower than those of thiophanate-methyl. The anti-microbial activity of glabridin is the strongest， and except for the EC₅₀ value against Colletotrichum gloeosporioides， which is 48.90 μg·mL^-1， the EC₅₀ values against other test pathogens are all smaller than 10.00 μg·mL^-1， meanwhile its EC₅₀ and EC₉₀ values against R. solani， Fusarium oxysporum， B. cinerea， and Fusarium graminearum are generally significantly lower than those of thiophanate-methyl. The EC₅₀ value of isoliquiritigenin against X. oryzae pv. oryzae is only 2.98 μg·mL^-1， which is not significantly different from that of control bactericide bismerthiazol. It is suggested that 4′-O-methylglabridin， hispaglabridin B， and glabridin possess broad-spectrum anti-microbial activities， and can be developed as leads of novel bio-pesticide； isoliquiritigenin possesses potent anti-microbial activity against X. oryzae pv. oryzae， and can be used as a lead for developing control agents against bacterial disease.