Nostosin G and Spiroidesin B from the Cyanobacterium Dolichospermum sp. NIES-1697

Abstract

Chemical investigation of the cyanobacterium Dolichospermum sp. NIES-1697 afforded nostosin G (1), a linear tripeptide, spiroidesin B (2), and two known compounds, anabaenopeptins I (3) and J (4). Planar structures and absolute configurations for 1 and 2 were determined by 2D NMR, HRMS, Marfey’s methodology, chiral-phase HPLC, and enzymatic degradation. Nostosin G (1) is a unique example of a linear peptide containing three subunits, 4-hydroxyphenyllactic acid (Hpla), homotyrosine (Hty), and argininal, with potent trypsin inhibitory properties. The biosynthetic gene clusters for nostosin G (1) and spiroidesin B (2) were investigated based on the genome sequence of Dolichospermum sp. NIES-1697.

Noducyclamides A1–A4, B1, and B2 from the Cyanobacterium Nodularia sp. NIES-3585

“…The hydrophilic fraction was further separated by octadecylsilyl (ODS) column chromatography, and the fractions were monitored by liquid chromatography−mass spectrometry (LC-MS) analysis. The major compounds noducyclamides A1 (1), A2 (2), and B1 (5) and minor compounds noducyclamides A3 (3), A4 (4), and B2 (6) eluted in the 80% MeOH fraction. Noducyclamide A1 (1) was acquired as a white amorphous powder, and the structure was determined by NMR, MS, and Marfey's methodology (Table 1 and Figures The 1 H and 13 C NMR spectra in DMSO-d 6 (Table 1) showed eight signals for the Cα methines of α-amino acids, one Cα methylene, Cα and Cβ positions of a β-amino acid (δ C 44.1, 39.3; δ H 4.29, 1.81, 1.72), and 10 signals for NH protons, suggesting a cyclic decapeptide.…”

“…Natural products from cyanobacteria frequently show interesting biological activities such as antimicrobial, biosurfactant, cytotoxic, and enzyme inhibitory activities. − Cyanobacteria are known to produce diverse cyclic lipopeptides that often contain β-amino fatty acids and form macrolactone or macrolactam rings . These cyclic lipopeptides can be categorized into different structural classes; among them the cyclic peptides containing 8–12 amino acids with long saturated β-amino fatty acids are limited to the hormothamnins, , hassallidins, , puwainaphycins/minutissamides, , and laxaphycins .…”

Natural Products That Contain Higher Homologated Amino Acids

“…All of them contain at least one hTyr or hPhe except for grassystatin B that contains a hAla residue. They exhibited protease inhibitory activity [19j,29–30] except for schizotrin A derivatives, such as lyngbyazothrins A–D, pahayokolides A and B, and tychonamides A and B that were not tested for protease inhibitions. Lyngbyazothrins A–D were evaluated for antibacterial activity, and only the combination of lyngbyazothrins C and D showed significant activity against Bacillus subtilis , Escherichia coli , Pseudomonas aeruginosa , and Serratia marcescens [32] .…”

“…The backbone structure of RiPPs is synthesized by the ribosome, and each residue is modified by tailoring enzymes [117] . All homoAA‐containing NPs whose biosynthesis is known or proposed are NRPs [16b,17a,18a,c,d,24d,25a,28c,30,43b,51a,56–57,58c,59,63–64,65c,70,72,84l,91a,c,93c,118] with a few exceptions, including phaseolotoxin (Figure 14), [119] ophthalmic acid (Figure 20), [112] and fungal compounds 7 and 8 (Figure 17). [98] As many of the proposed or characterized homologation pathways require the modification of the backbone structure, it would be more reasonable that the NRP structure is assembled after homologation happens to the amino acid.…”

Absolute Stereochemistry Determination of Bioactive Marine-Derived Cyclopeptides by Liquid Chromatography Methods: An Update Review (2018–2022)

“…In some cases, a combination of both methods are found to be necessary for the absolute configurations assessment of all the amino acid residues [ 110 ]. In addition, LC methods are also widely used for the assignment of the absolute configurations of peptides isolated from natural sources other than marine organisms [ 111 , 112 , 113 , 114 ].…”