cid substitutions responsible for their diversity (Supplementary Table S1). Having said that, these peptides do not possess a fully systematic nomenclature, which can make it tough to recognize them as a member of a certain group of oligopeptides with similar struc-Toxins 2021, 13,6 ofture. This truth just isn’t specific to Anabaenopeptins, but cyanopeptides generally, as their denominations are often referring to the taxon or geographic locality from which the oligopeptide had been isolated, as well as details regarding molecular weight, specific residues, or even the strain number can be used as a Caspase 8 web suffix, and a few instance could be noticed applied to APs [11]. One particular example of a variant using a distinct name may be the Schizopeptin 791 (Figure three), 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 right after their isolation from the filamentous freshwater cyanobacterium Lyngbya sp. SAG 36.91. These anabaenopeptin-like peptides also have an uncommon feature due to the presence of a D-Phenylalanine within the exocyclic position, being the only APs bearing an amino acid in D-configuration within this position [47]. Obtained from the marine Lyngbya confervoides, Pompanopeptin B is definitely an anabaenopeptin-type peptide bearing inside the fifth position the N-methyl-2-amino-6-(four hydroxyphenyl)hexanoic acid (N-Me-Ahpha), a methylated kind of a residue found in Largamide C [23]. Nodulapeptins are also anabaenopeptin-like peptides and they were 1st identified by Fujii and co-workers [48] inside the toxic Nodularia spumigena AV1. Amongst the various nomenclature of this class of cyclic hexapeptide, Nodulapeptin is amongst the most utilised and it can be usually connected together with the presence of Methionine (Met) or Serine (Ser) residues in position 6 of anabaenopeptin-like JNK3 Compound structures [49]. Isolated in the cyanobacteria Tychonema sp., Brunsvicamides A-C share a high resemblance to anabaenopeptin-like peptides obtained from sponges, therefore indicating their achievable cyanobacterial origin. These peptides obtained from a Tychonema sp. strain did not possess any homoamino acid and have a L-Lys besides D-Lys, in addition, Brunsvicamide C has an N-methyl-N’-formyl-Dkynurenine unit in position 5 [50]. Apart from these distinct nomenclatures and structures for Anabaenopeptins obtained from cyanobacteria, this class of peptides can also be found in sponges, which were the initial organisms to be identified the very first anabaenopeptin-related compound, not in a cyanobacterium [31,32]. Konbamide and Keramide A (Table 1 and Figure four) were isolated in the marine sponge Theonella sp., which showed distinct characteristics from cyanobacterial anabaenopeptins possessing a cyclic hexapeptide structure and also 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 six; in comparison, Keramide A possessed a 6-chloro-5-hydroxy-N-methyltryptophan (5’OH6’ClTrp) in position 5 [31,32]. Keramide L was 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 options to Konbamide and Keramide A, getting a modified Trp residue in position five: a 6-chloro-N-methyltryptophan (NMe-6’ClTrp) residue [30]. Besides, the marine sponge Theonella sw