Anabaenopeptins from Cyanobacteria in Freshwater Bodies of Greece

Abstract

Cyanobacteria are photosynthetic microorganisms that are able to produce a large number of secondary metabolites. In freshwaters, under favorable conditions, they can rapidly multiply, forming blooms, and can release their toxic/bioactive metabolites in water. Among them, anabaenopeptins (APs) are a less studied class of cyclic bioactive cyanopeptides. The occurrence and structural variety of APs in cyanobacterial blooms and cultured strains from Greek freshwaters were investigated. Cyanobacterial extracts were analyzed with LC–qTRAP MS/MS using information-dependent acquisition in enhanced ion product mode in order to obtain the fragmentation mass spectra of APs. Thirteen APs were detected, and their possible structures were annotated based on the elucidation of fragmentation spectra, including three novel ones. APs were present in the majority of bloom samples (91%) collected from nine Greek lakes during different time periods. A large variety of APs was observed, with up to eight congeners co-occurring in the same sample. AP F (87%), Oscillamide Y (87%) and AP B (65%) were the most frequently detected congeners. Thirty cyanobacterial strain cultures were also analyzed. APs were only detected in one strain (Microcystis ichtyoblabe). The results contribute to a better understanding of APs produced by freshwater cyanobacteria and expand the range of structurally characterized APs.

Lake Avernus Has Turned Red: Bioindicator Monitoring Unveils the Secrets of “Gates of Hades”

“…A manual in-depth analysis of HRMS/MS spectra allowed identification of compounds 5 and 6 as anabaenopeptin F and anabaenopeptin 820 [ 22 ], respectively. These latter two compounds were not annotated by Dereplicator+.…”

Anabaenopeptins from Nostoc edaphicum CCNP1411

“…The main reasons for a wide interest in anabaenopeptins are their frequent occurrence in various taxonomic groups of cyanobacteria and their biological activity [23,24,40,51,56,77,84]. The promising activity of APs with respect to pharmaceutical application was documented for TAFIa [56].…”

“…The structure of APs comprises a five-membered peptide ring linked through the ureido bond with one amino acid side chain. The general formula of this class of peptides is X 1 -CO-[Lys 2 -X 3 -X 4 -MeX 5 -X 6 ], where Lys 2 in D-configuration is the only conservative amino acid in the structure [35,50,51]. Positions 4 and 5 are often occupied by homoamino acids (e.g., Hph, Hty) and N-methylated amino acids (e.g., MeAla, MeHty, MeAsn or MeHph).…”

“…Peptides with typical AP structural features were named arbitrarily, so their nomenclature is not systematic. Among the 155 identified APs [51], there are structural variants of the compounds named nodulapeptins [15], brunsvicamides [32], ferintoic acids [52], lyngbyaureidamides [20], nostamides [4,6], oscillamides [21,24], pompanopeptins [19], schizopeptin [44], mozamides [48], paltolides [53] and psymbamide [54]. Of these, 38 are produced by cyanobacteria of the genus Nostoc, isolated mainly from terrestrial environments (Tables 1 and S1).…”

Effect of abiotic factors on the stability of chosen oligopeptides isolated from the freshwater cyanobacterium Woronichinia naegeliana

“…Cyanopeptides contain unusual amino acids and are structurally classified as linear (aeruginosins, microginins), cyclic (anabaenopeptins, cyanopeptolins, cyclamides) or multicyclic (microviridins) (Welker and von Döhren 2006). Among them, anabaenopeptins and cyanopeptolins are frequently detected in freshwater bodies at concentrations up to 10 µg L −1 that may exceed 1000 µg L −1 during blooms (Gkelis et al 2015;Janssen 2019;Zervou et al 2022). These cyclic nonribosomal oligopeptides have been identified in cyanobacteria of the genera Anabaena, Microcystis, Planktothrix, Lyngbya, Nodularia, Schizotrix, Nostoc Planktothrix, Scytonema, Symploca and Woronichinia (Le Manach et al 2019;Bober et al 2021).…”