cid substitutions responsible for their diversity (Supplementary Table S1). Even so, these peptides do not possess a completely systematic nomenclature, which can make it difficult to identify them as a member of a certain group of oligopeptides with equivalent struc-Toxins 2021, 13,6 ofture. This truth just isn’t particular to Anabaenopeptins, but cyanopeptides in general, as their denominations are often referring towards the taxon or geographic locality from which the oligopeptide had been isolated, and also details relating to molecular weight, particular residues, or even the strain number is often employed as a suffix, and a few example may be observed applied to APs [11]. 1 instance of a variant with a distinct name would be the Schizopeptin 791 (Figure 3), which was named following the terrestrial cyanobacteria Schizothrix sp. IL-2082-2 (Schizo-), its peptide nature (-peptin) and its molecular weight of 791 Da (791) [46]. Lyngbyaureidamides A and B are Anabaenopeptins named following their isolation in the filamentous freshwater cyanobacterium Lyngbya sp. SAG 36.91. These anabaenopeptin-like peptides also have an uncommon feature as a result of presence of a D-Phenylalanine within the exocyclic position, HIV-1 custom synthesis getting the only APs bearing an amino acid in D-configuration within this position [47]. Obtained in the marine Lyngbya confervoides, Pompanopeptin B is an anabaenopeptin-type peptide bearing in the fifth position the N-methyl-2-amino-6-(4 hydroxyphenyl)hexanoic acid (N-Me-Ahpha), a methylated kind of a residue located in Largamide C [23]. Nodulapeptins are also anabaenopeptin-like peptides and they were initial identified by Fujii and co-workers [48] in the toxic Nodularia spumigena AV1. Amongst the distinctive nomenclature of this class of cyclic hexapeptide, Nodulapeptin is among the most applied and it is often linked using the presence of Methionine (Met) or Serine (Ser) residues in position six of anabaenopeptin-like structures [49]. Isolated in the cyanobacteria Tychonema sp., Brunsvicamides A-C share a higher resemblance to anabaenopeptin-like peptides obtained from sponges, hence indicating their achievable cyanobacterial origin. These peptides obtained from a Tychonema sp. strain did not possess any homoamino acid and have a L-Lys apart from D-Lys, additionally, Brunsvicamide C has an N-methyl-N’-formyl-Dkynurenine unit in position 5 [50]. In addition to these distinct nomenclatures and structures for Anabaenopeptins obtained from cyanobacteria, this class of peptides may also be identified in sponges, which had been the initial organisms to become identified the first anabaenopeptin-related compound, not in a cyanobacterium [31,32]. Konbamide and Keramide A (Table 1 and Figure four) had been isolated from the marine sponge Theonella sp., which showed distinct options from cyanobacterial anabaenopeptins getting a cyclic hexapeptide structure as well as the presence of an ureido bond. Each variants have L-Lys residue as well as they contain a modified Tryptophan (Trp) residue at position six. Konbamide had 2-bromo-5-hydroxytryptophan (2’Br-Trp) in position 6; in comparison, Keramide A possessed a 6-chloro-5-hydroxy-N-methyltryptophan (5’OH6’ClTrp) in position 5 [31,32]. Keramide L was 5-HT Receptor Purity & Documentation detected in Theonella sp. SS-342 with each other with Keramide K (a thiazole-containing cyclic peptide not belonging to anabaenopeptin-class). Keramide L shared similar features to Konbamide and Keramide A, possessing a modified Trp residue in position 5: a 6-chloro-N-methyltryptophan (NMe-6’ClTrp) residue [30]. In addition to, the marine sponge Theonella sw