大蒜白斑病菌SS-毒素的结构鉴定

Structural identification of SS-toxin produced by Stemphylium solani causing garlic leaf blight

大蒜白斑病是由Stemphylium solani引起的一种重要的大蒜病害,病菌可产生致病毒素SS-毒素。本文采用薄层层析和高效液相色谱法对该毒素进行分离纯化,结合化学鉴定、紫外可见吸收光谱、红外光谱、质谱、元素分析以及核磁共振等方法鉴定毒素结构。通过化学反应可初步判断该毒素是一种酚类物质;毒素在215、264和458 nm处有紫外可见吸收峰;在红外光谱中可看出,毒素结构中有酚-OH(3 400 cm-1)、-CH3(2 946 cm-1、1 449 cm-1、1 395 cm-1)、芳香环(3 092 cm-1、1 595 cm-1)、-CO(1 670 cm-1)和酮-C=O(1 640 cm-1)存在的伸缩振动;根据电喷雾质谱和元素分析结果得到SS-毒素的分子式为C16H16O8;进一步结合毒素的核磁共振氢谱和碳谱将SS-毒素鉴定为7-甲氧基-2-甲基-1,2,3,4-四氢-1,2,3,4,5-五羟基蒽醌。本文是首次对S.solani致病毒素的化学结构进行鉴定。

Garlic leaf blight caused by Stemphylium solani is an important garlic disease. A phytotoxin, SS-toxin from culture filtrate of S. solani was extracted and purified by using TLC and HPLC methods. SS-toxin gave a positive ferric chloride test and exhibited UV absorption maxima at 215, 264 and 458 nm, which indicated an aromatic structure is present in the toxin. Characteristic absorptions of the toxin for hydroxyl groups （3 400 cm-1 ）, methyl groups （2 946 cm-1, 1 449 cm-1 and 1 395 cm-1 ）, aromatic rings （3 092 cm-1 and 1 595 cm-1）, unchelated CO （1 670 cm-1） and conjugated CO （1 640 cm-1） were displayed with IR spectrum. The results of ESI-MS together with elemental analysis suggested that the molecular formula of SS-toxin is C16H1608. The structure of SS-toxin was further identified as 7-methoxy-2-methyl-1,2,3,4-tetrahydro-1,2,3,4,5-penta- hydroxyanthraquinone based on the data of UV, IR, 1H-NMR and 13C-NMR spectra. This is the first report on identification of the chemical structure of a phytotoxin isolated from S. solani.