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Relevant academic research and scientific papers

Jubanines F-J, cyclopeptide alkaloids from the roots of Ziziphus jujuba

Five Ib-type cyclopeptide alkaloids, jubanines F-J (1-5), and three known compounds, nummularine B (6), daechuine-S3 (7), and mucronine K (8) were isolated from the roots of Ziziphus jujuba. Their structures were fully characterized by spectroscopic analyses in combination with chemical derivatization. Compounds 1-3, and 6 were evaluated for their antiviral activity against the porcine epidemic diarrhea virus (PEDV). Compounds 2, 3, and 6 showed potent inhibitory effects on PEDV replication.

Pithohirolide, an antimicrobial tetradepsipeptide from a fungus Pithomyces chartarum

Pithohirolide (1), a new depsipeptide, was isolated from an ascomycetous fungus Pithomyces chartarum TAMA 581. The planar structure of 1 was elucidated on the basis of NMR and MS analyses and the absolute configuration was determined by the advanced Marfey’s analysis, chiral-phase HPLC analysis, and synthesis of degradation product. Compound 1 possesses a cyclic structure comprising (S)-2-hydroxy-3-phenylpropanoic acid, (S)-3-hydroxy-3-phenylpropanoic acid, (S)-2-hydroxyisovaleric acid, and N-methyl-l-alanine, connected via three ester and one amide linkages. Compound 1 exhibited antimicrobial activity against Staphylococcus aureus and Saccharomyces cerevisiae at MIC 3.1 μg ml?1.

Urumamide, a novel chymotrypsin inhibitor with a β-amino acid from a marine cyanobacterium Okeania sp.

Urumamide, a novel cyclic depsipeptide that contains a β-amino acid, was isolated from a marine cyanobacterium Okeania sp. Its gross structure was determined by spectroscopic analyses, and the absolute configuration was established based on Marfey's analyses and chiral HPLC analyses of hydrolysis products. Biologically, urumamide inhibited the growth of human cancer cells. In addition, urumamide inhibited chymotrypsin.

Stellettapeptins A and B, HIV-inhibitory cyclic depsipeptides from the marine sponge Stelletta sp.

Two new HIV-inhibitory depsipeptides, stellettapeptins A (1) and B (2), were isolated from an extract of the marine sponge Stelletta sp., collected from northwestern Australia. Structures of these cyclic nonribosomal peptides were elucidated on the basis of extensive NMR data analysis, and chemical degradation and derivatization studies. Stellettapeptins contain numerous nonproteinogenic amino acid residues and they are the first peptides reported to contain a 3-hydroxy-6,8-dimethylnon-4-(Z)-enoic acid moiety. Compounds 1 and 2 potently inhibit infection of human T-lymphoblastoid cells by HIV-1RF with EC50 values of 23 and 27 nM, respectively.

Cyclic depsipeptides, grassypeptolides D and e and Ibu- epidemethoxylyngbyastatin 3, from a Red Sea Leptolyngbya cyanobacterium

Two new grassypeptolides and a lyngbyastatin analogue, together with the known dolastatin 12, have been isolated from field collections and laboratory cultures of the marine cyanobacterium Leptolyngbya sp. collected from the SS Thistlegorm shipwreck in the Red Sea. The overall stereostructures of grassypeptolides D (1) and E (2) and Ibu-epidemethoxylyngbyastatin 3 (3) were determined by a combination of 1D and 2D NMR experiments, MS analysis, Marfey's methodology, and HPLC-MS. Compounds 1 and 2 contain 2-methyl-3-aminobutyric acid and 2-aminobutyric acid, while biosynthetically distinct 3 contains 3-amino-2-methylhexanoic acid and the β-keto amino acid 4-amino-2,2-dimethyl-3-oxopentanoic acid (Ibu). Grassypeptolides D (1) and E (2) showed significant cytotoxicity to HeLa (IC50 = 335 and 192 nM, respectively) and mouse neuro-2a blastoma cells (IC50 = 599 and 407 nM, respectively), in contrast to Ibu-epidemethoxylyngbyastatin 3 (neuro-2a cells, IC50 > 10 μM) and dolastatin 12 (neuro-2a cells, IC 50 > 1 μM).