基于质谱成像技术的独活鲜根中香豆素类成分的空间分布特征研究

Spatial distribution of coumarins in Angelica pubescens fresh roots byMALDI-MSI

目的 基质辅助激光解吸质谱成像技术是一种新型的分子成像和原位检测技术,具有免标记,高灵敏度和高通量等优势。采用质谱成像技术研究独活Angelica pubescens中香豆素类化合物的空间分布特征。方法 以蛇床子素和二氢欧山芹醇当归酸酯等为对照品分别在正、负2种离子检测模式下对基质2,5-二羟基苯甲酸、9-氨基吖啶和α-氰基-4-羟基肉桂酸进行筛选。根据质谱信号确定α-氰基-4-羟基肉桂酸为基质,并在正离子模式下进行成像分析。以收获期独活作为研究对象,将基质喷涂于25μm的独活根组织切片上进行质谱成像分析,研究了根和根皮中香豆素类化合物的空间分布信息及特征。结果 通过质谱成像分析,在独活根和根皮中分别鉴别出25和28个香豆素类成分。其中蛇床子素、东莨菪内酯、白花前胡醇、紫花前胡素、佛手酚和川白芷素6种成分主要分布在韧皮部分泌腔和分泌道等分泌组织中,二氢欧山芹醇乙酸酯、二氢欧山芹醇当归酸酯、白当归素和新比克白芷内酯4种主要分布在除分泌腔以外的木质部和韧皮部,其他成分在根中均匀分布,无明显特征。结论 建立的质谱成像方法能简便、快速和直接的对独活中的香豆素类活性成分进行原位分析,对观察植物组织中代谢物的空间分布具有独特的效果。

Objective Matrix assisted laser desorption mass spectrometry imaging(MALDI-MSI)is a new molecular imaging and in-situ detection technology,which has the advantages of label free,high sensitivity and high throughput.In this study,the spatial distribution characteristics of coumarins in Angelica pubescens roots were studied by MALDI-MSI.Methods In this study,osthol and columbianadin were used as the control substances to detect matrixα-cyano-4-hydroxycinnamic acid(CHCA),2,5-dihydroxybenzoic acid(DHB)and 9-aminoacridineare(9-AA)were screened under positive and negative modes.CHCA was used as the matrix and imaging analysis was carried out in positive ion mode,which were determined by mass spectrum signal.In this paper,A.pubescens in harvest period was taken as the research object,and the substrate was sprayed on root tissue section(25μm)for mass spectrometry imaging,and the spatial distribution information and characteristics of coumarins in roots and root bark were obtained.Results By mass spectrometry imaging analysis,25 and 28 coumarins were identified in root and root bark of A.pubescens,respectively.Among them,osthol,scopolactone,ulopterol,decursin,bergamol and angelicol are mainly distributed in the secretory tissues of phloem,such as secretory cavities and secretory ducts,while dihydroparsley acetate,dihydroparsley angelic acid ester,angelicin leucin and neobik angelicolide are mainly distributed in xylem and phloem except secretory cavities.Other components are evenly distributed in roots without obvious characteristics.Conclusion The established mass spectrometry imaging method could be used for simple,rapid and direct in-situ analysis of coumarins in A.pubescens roots,and has a unique effect on observing the spatial distribution of metabolites in plant tissues.