199729-72-1

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• 673-06-3 D-(R)-phenylalanine 
• 1393002-32-8 C₃₃H₄₆N₆O₅S 

Relevant academic research and scientific papers

Thiazoline peptides and a tris-phenethyl urea from Didemnum molle with Anti-HIV activity

As part of our screening for anti-HIV agents from marine invertebrates, the MeOH extract of Didemnum molle was tested and showed moderate in vitro anti-HIV activity. Bioassay-guided fractionation of a large-scale extract allowed the identification of two new cyclopeptides, mollamides E and F (1 and 2), and one new tris-phenethyl urea, molleurea A (3). The absolute configurations were established using the advanced Marfey's method. The three compounds were evaluated for anti-HIV activity in both an HIV integrase inhibition assay and a cytoprotective cell-based assay. Compound 2 was active in both assays with IC50 values of 39 and 78 μM, respectively. Compound 3 was active only in the cytoprotective cell-based assay, with an IC50 value of 60 μM.

Melicopteline A-E, Unusual Cyclopeptide Alkaloids with Antiviral Activity against Influenza A Virus from Melicope pteleifolia

In the search for antiviral cyclopeptides against influenza A virus, five unprecedented Caryophyllaceae-type cyclopeptides (1-5) were isolated from the leaves of Melicope pteleifolia. Their chemical structures and absolute configurations were unambiguousl

Argicyclamides A-C Unveil Enzymatic Basis for Guanidine Bis-prenylation

Guanidine prenylation is an outstanding modification in alkaloid and peptide biosynthesis, but its enzymatic basis has remained elusive. We report the isolation of argicyclamides, a new class of cyanobactins with unique mono- and bis-prenylations on guanidine moieties, from Microcystis aeruginosa NIES-88. The genetic basis of argicyclamide biosynthesis was established by the heterologous expression and in vitro characterization of biosynthetic enzymes including AgcF, a new guanidine prenyltransferase. This study provides important insight into the biosynthesis of prenylated guanidines and offers a new toolkit for peptide modification.

Coculture of a Pathogenic Actinomycete and Animal Cells to Produce Nocarjamide, a Cyclic Nonapeptide with Wnt Signal-Activating Effect

A coculture method with a pathogenic actinomycete of the genus Nocardia and an animal cell line was designed to reconstruct and emulate the initial infection state, and a new cyclic nonapeptide, named nocarjamide (1), was obtained by coculture of Nocardia tenerifensis IFM 10554T and the mouse macrophage-like cell line J774.1 in a modified Czapek-Dox medium. Nocarjamide (1) exhibited Wnt signal-activating effects.

Octaminomycins A and B, cyclic octadepsipeptides active against Plasmodium falciparum

Two new cyclic octadepsipeptides, octaminomycins A (1) and B (2), were isolated from a microbial metabolite fraction library of Streptomyces sp. RK85-270 based on Natural Products Plot screening. Their structures were elucidated on the basis of HRESIMS, 1D and 2D NMR spectroscopic data, and MS/MS experiments for sequence analysis. The absolute configurations of the constituent amino acid residues were determined by a combination of single-crystal X-ray diffraction and Marfey's methodology. Notably, octaminomycins A (1) and B (2) showed good in vitro antiplasmodial activity against chloroquine-sensitive as well as chloroquine-resistant strains with no cytotoxicity up to 30 μM. (Chemical Equation Presented).

Ulleungamides A and B, Modified α,β-Dehydropipecolic Acid Containing Cyclic Depsipeptides from Streptomyces sp. KCB13F003

Two novel cyclic depsipeptides, ulleungamides A (1) and B (2), were isolated from cultures of terrestrial Streptomyces sp. Their structures were determined by analyses of spectroscopic data and various chemical transformations, including modified Mosher's method, advanced Marfey's method, PGME, GITC derivatizations, and Snatzke's method. Ulleungamides were determined to be a new class of peptides bearing unprecedented units, such as 5-hydroxy-6-methyl-2,3-dehydropipecolic acid, 4,5-dihydroxy-6-methyl-2,3-dehydropipecolic acid, and amino-linked 2-isopropylsuccinic acid. Ulleungamide A displayed growth inhibitory activity against Staphylococcus aureus and Salmonella typhimurium without cytotoxicity.

Application of 3D NMR for Structure Determination of Peptide Natural Products

Despite the advances in NMR, structure determination is often slow and constitutes a bottleneck in natural products discovery. Removal of this bottleneck would greatly improve the throughput for antibiotic discovery as well as other therapeutic areas. Overall, faster structure methods for structure determination will serve the natural products community in a broad manner. This report describes the first application of 3D NMR for elucidation of two microbially produced peptide natural products with novel structures. The methods are cost-effective and greatly improve the confidence in a proposed structure.

Callyaerins A-F and H, new cytotoxic cyclic peptides from the Indonesian marine sponge Callyspongia aerizusa

Bioassay guided fractionation of the EtOAc fraction of the sponge Callyspongia aerizusa yielded seven new cytotoxic cyclic peptides callyaerins A-F (1-6) and H (8). Their structures were determined using extensive 1D ( 1H, 13C and DEPT) and 2D (COSY, HMQC, HMBC, TOCSY, and ROESY) NMR and mass spectral (ESI and HRESI-TOF) data. All compounds were cyclic peptides containing ring systems of 5-9 amino acids and side chains of 2-5 amino acids in length. An unusual (Z)-2,3-diaminoacrylic acid unit provided the template for ring closure and afforded the linkage to the peptidic side chain which was always initiated with a proline moiety. All peptides contained three or more proline residues and the remaining residues were predominantly hydrophobic residues with all amino acids present in the l form. Callyaerins A-F (1-6) and H (8) showed biological activity in antibacterial assays and in various cytotoxicity assays employing different tumour cell-lines (L5178Y, HeLa, and PC12). Callyaerins E (5) and H (8) exhibited strong activity against the L5178Y cell line with ED50 values of 0.39 and 0.48 μM, respectively. On the other hand, callyaerin A (1) showed strong inhibitory properties towards C. albicans.