Department of Chemistry, Carleton University, Ottawa, Ontario, Canada.
London Research and Development Center, Agriculture and Agri-Food Canada, London, Ontario, Canada.
Environ Toxicol Chem. 2021 Apr;40(4):1087-1097. doi: 10.1002/etc.4941. Epub 2021 Feb 1.
Cyanobacteria are ubiquitous photosynthetic prokaryotes that produce structurally diverse bioactive metabolites. Although microcystins are extensively studied, other cyanopeptides produced by common bloom-forming species have received little attention. Cyanopeptolins are a large cyanopeptide group that contain a characteristic 3-amino-6-hydroxy-2-piperidone (Ahp) moiety. In the present study we used diagnostic fragmentation filtering (DFF), a semitargeted liquid chromatography-tandem mass spectrometry (MS/MS) product ion filtering approach, to investigate cyanopeptolin diversity from 5 Microcystis strains and 4 bloom samples collected from lakes in Ontario and Quebec, Canada. Data processing by DFF was used to search MS/MS data sets for pairs of diagnostic product ions corresponding to cyanopeptolin partial sequences. For example, diagnostic product ions at m/z 150.0912 and 215.1183 identified cyanopeptolins with the NMe-Tyr-Phe-Ahp partial sequence. Forty-eight different cyanopeptolins, including 35 new variants, were detected from studied strains and bloom samples. Different cyanopeptolin profiles were identified from each sample. We detected a new compound, cyanopeptolin 1143, from a bloom and elucidated its planar structure from subsequent targeted MS/MS experiments. Diagnostic fragmentation filtering is a rapid, easy-to-perform postacquisition metabolomics strategy for inferring structural features and prioritizing new compounds for further study and dereplication. More work on cyanopeptolin occurrence and toxicity is needed because their concentrations in freshwater lakes after blooms can be similar to those of microcystins. Environ Toxicol Chem 2021;40:1087-1097. © 2020 SETAC.
蓝藻是普遍存在的光合原核生物，能产生结构多样的生物活性代谢物。尽管微囊藻毒素的研究较为广泛，但常见水华形成物种产生的其他环肽却鲜少受到关注。环缩肽是一个大型的环肽组，含有特征性的 3-氨基-6-羟基-2-哌啶酮（Ahp）部分。在本研究中，我们使用诊断性片段过滤（DFF），一种半靶向液相色谱-串联质谱（MS/MS）产物离子过滤方法，来研究来自加拿大安大略省和魁北克省的 5 株微囊藻和 4 个水华样本中的环缩肽多样性。通过 DFF 对数据进行处理，用于在 MS/MS 数据集内搜索与环缩肽部分序列相对应的一对诊断性产物离子。例如，质荷比为 150.0912 和 215.1183 的诊断性产物离子可鉴定出具有 NMe-Tyr-Phe-Ahp 部分序列的环缩肽。从研究的菌株和水华样本中检测到 48 种不同的环缩肽，其中包括 35 种新变体。从每个样本中鉴定出不同的环缩肽图谱。我们从一个水华样本中检测到一种新化合物，环缩肽 1143，并通过随后的靶向 MS/MS 实验阐明了其平面结构。诊断性片段过滤是一种快速、易于执行的代谢组学后获取策略，用于推断结构特征，并为进一步研究和去重优先级排序新化合物。由于水华后在淡水湖中它们的浓度与微囊藻毒素相似，因此需要对环缩肽的发生和毒性进行更多研究。 Environ Toxicol Chem 2021;40:1087-1097. © 2020 SETAC.
