Demeyer Marie, Wisztorski Maxence, Decroo Corentin, De Winter Julien, Caulier Guillaume, Hennebert Elise, Eeckhaut Igor, Fournier Isabelle, Flammang Patrick, Gerbaux Pascal
Organic Synthesis and Mass Spectrometry Laboratory, University of Mons-UMONS, 23 Place du Parc, 7000, Mons, Belgium.
Biology of Marine Organisms and Biomimetics, University of Mons-UMONS, 23 Place du Parc, 7000, Mons, Belgium.
Anal Bioanal Chem. 2015 Nov;407(29):8813-24. doi: 10.1007/s00216-015-9044-0. Epub 2015 Sep 28.
Saponins are secondary metabolites that are abundant and diversified in echinoderms. Mass spectrometry is increasingly used not only to identify saponin congeners within animal extracts but also to decipher the structure/biological activity relationships of these molecules by determining their inter-organ and inter-individual variability. The usual method requires extensive purification procedures to prepare saponin extracts compatible with mass spectrometry analysis. Here, we selected the sea star Asterias rubens as a model animal to prove that direct analysis of saponins can be performed on tissue sections. We also demonstrated that carboxymethyl cellulose can be used as an embedding medium to facilitate the cryosectioning procedure. Matrix-assisted laser desorption/ionization (MALDI) imaging was also revealed to afford interesting data on the distribution of saponin molecules within the tissues. We indeed highlight that saponins are located not only inside the body wall of the animals but also within the mucus layer that probably protects the animal against external aggressions. Graphical Abstract Saponins are the most abundant secondary metabolites in sea stars. They should therefore participate in important biological activities. Here, MALDI imaging is presented as a powerful method to determine the spatial distribution of saponins within the animal tissues. The inhomogeneity of the intra-organ saponin distribution is highlighted, paving the way for future elegant structure/activity relationship investigations.
皂苷是在棘皮动物中丰富多样的次生代谢产物。质谱法不仅越来越多地用于鉴定动物提取物中的皂苷同系物，还通过确定其器官间和个体间的变异性来解读这些分子的结构/生物活性关系。常规方法需要广泛的纯化程序来制备与质谱分析兼容的皂苷提取物。在这里，我们选择海星红斑海盘车作为模型动物，以证明可以在组织切片上直接分析皂苷。我们还证明了羧甲基纤维素可以用作包埋介质以促进冷冻切片程序。基质辅助激光解吸/电离（MALDI）成像也被证明可以提供有关皂苷分子在组织内分布的有趣数据。我们确实强调，皂苷不仅位于动物的体壁内，还存在于可能保护动物免受外部侵害的黏液层中。图形摘要 皂苷是海星中最丰富的次生代谢产物。因此，它们应该参与重要的生物活动。在这里，MALDI成像被展示为一种确定皂苷在动物组织内空间分布的强大方法。突出了器官内皂苷分布的不均匀性，为未来精细的结构/活性关系研究铺平了道路。
