红车轴草对莴苣生长抑制作用研究

Inhibitory effect of Trifolium pratense on the growth of Lactuca sativa seedlings

采用活体生物试验方法,首次比较研究了红车轴草根乙醇提取物及不同极性溶剂萃取物对莴苣的生长抑制作用,并在此基础上分离鉴定了活性化合物的化学结构,进一步对其活性作用机理进行了研究。试验表明,红车轴草根乙醇提取物对莴苣种子萌发和幼苗生长具有较强的抑制作用,4种萃取物表现出不同程度的抑制效应,其中氯仿和乙酸乙酯萃取部位抑制强度最大,是红车轴草根植物毒活性有效部位。为明确红车轴草抑制莴苣幼苗生长的活性化学物质基础,采用活性跟踪分离方法,从氯仿萃取物中分离得到1种黄酮苷类化合物,运用波谱学技术确定了其化学结构,鉴定为(6aR,11aR)-三叶豆紫檀苷。活性测定发现,该苷类化合物能够显著降低莴苣幼苗的鲜重和根长,低浓度处理使莴苣体内的抗氧化酶SOD和CAT含量升高,随着处理浓度增加,SOD、CAT含量显著降低,导致植物体内活性氧升高,造成细胞膜脂过氧化伤害,影响植物生长相关的生理过程。

The inhibitory effects on Lactuca sativa of the root extracts and fractions prepared with different solvents from Trifolium pratense were tested and compared by living-bioassay methods.The ethanol extract showed a significant inhibitory effect on the germination and growth of L.sativa seeds and seedlings.The chloroform and ethylacetate extracts of the root showed stronger inhibitory effects and were determined as the effective phytotoxic fractions of T.pratense.The bioactivity-driven fractionation of the chloroform extract led to the purification of a flavonoid glycoside,which was characterized（mainly by NMR spectral elucidation） as（6aR,11aR）-trifolirhizin.This compound led to significant reductions of fresh weight and root length of L.sativa seedlings and stimulated the activity of SOD and CAT at lower concentrations but inhibited the activity of the enzymes at higher concentrations.Reactive oxygen species increased and the peroxidation of membrane lipid was induced by（6aR,11aR）-trifolirhizin at higher concentrations to affect the related physiological processes for the growth and development of plants.