西洋参中酚酸及皂苷成分对病原菌的作用

为了探讨西洋参(PanaxquinquefoliumL.)中主要次生代谢产物在防御病原菌侵染中的作用，建立了西洋参根中3种酚酸（p-香豆酸、阿魏酸、苯甲酸）含量的HPLC测定方法，并根据测定数据及前期研究结果，设计酚酸和皂苷提取物的实验浓度。选取立枯丝核菌(Rhizoctoniasolani)、茄病镰刀菌(Fusariumsolani)、尖孢镰刀菌(F.oxysporum)、毁灭柱孢菌(Cylindrocarpondestructans)4株西洋参病原菌，采用生长速率法测定酚酸和皂苷提取物对菌丝生长的作用。测定结果表明，3年生西洋参根内p-香豆酸、阿魏酸、苯甲酸的含量分别为(1.37±0.07)、(2.80±0.04)、(6.07±0.24)mg/kg，此浓度下的3种酚酸对4株病原菌无明显作用。皂苷提取物浓度在对应根内浓度的范围下(4~40mg/mL)，对立枯丝核菌、尖孢镰刀菌、毁灭柱孢菌均有显著抑制作用(P＜0.05)；当浓度达到40mg/mL时，对立枯丝核菌、茄病镰刀菌、尖孢镰刀菌、毁灭柱孢菌的抑制作用分别达到100%、83%、77%、58%(P＜0.05)。由此推论，在西洋参抵御病原菌侵染中，所含的皂苷类成分是重要的化学防御物质。

Effect of Phenolic Acid and Ginsenosides in American Ginseng on the Growth of Pathogenic Fungi

This study aimed to investigate the roles of major secondary metabolites in American ginseng (Panax quinquefolium L.) defensing against pathogens infection. Contents of three kinds of phenolic acids in root of American ginseng, including p-coumaric acid, ferulic acid and benzoic acid, were determined by using high performance liquid chromatography (HPLC). Sensitivities of four pathogenic fungi, including Rhizoctonia solani, Fusarium solani, F. oxysporum and Cylindrocarpon destructans, to phenolic acid or ginsenosides were analyzed using flat growth restraint method. The results showed that contents of p-coumaric acid, ferulic acid and benzoic acid were (1.37±0.07), (2.80±0.04), and (6.07±0.24) mg/kg in three-year-old American ginseng root, respectively. All the three kinds of phenolic acids showed no effect on the growth of four pathogenic fungi under these concentrations. However, R. solani, F. oxysporum and C. destructans were significantly inhibited by ginsenosides at concentration of 4~40 mg/mL, which were corresponding to the concentrations of ginsenosides in roots (P<0.05). Inhibition ratio on R. solani, F. solani, F. oxysporum and C. destructans were 100%, 83%, 77% and 58% respectively compared to corresponding control groups when concentration of ginsenosides was 40 mg/mL (P<0.05). The results suggested that ginsenosides was important in inhibiting pathogenic fungi as a kind of chemical defense compounds.