Polyketide derivatives of endophytic fungus Pestalotiopsis sp. isolated from the Chinese mangrove plant Rhizophora mucronata

A detailed chemical investigation of the minor metabolites produced by the endophytic fungus Pestalotiopsis sp. isolated from the Chinese mangrove Rhizophora mucronata afforded sixteen new compounds of polyketide origin, including pestalotiopyrones A-H (1-8), pestalotiopisorin A (10), pestalotiollides A-B (11-12), pestalotiopin A (13), and four amides pestalotiopamides A-D (14-17), along with three known compounds, nigrosporapyrone D (9), 2-anhydromevalonic acid (18), and p-hydroxy benzaldehyde (19). The structures of all compounds were unambiguously established from their spectroscopic data that included HR-ESIMS and 1- and 2-dimensional NMR spectroscopy, and by comparison with the literature.     

Formamidobisabolene-based derivatives from a sponge Axinyssa sp.

Chemical examination of a Chinese sponge Axinyssa sp. resulted in the isolation of 12 new formamidobisabolene-based analogues named axinyssines A–L (1–12), along with a new natural product (13) and three known formamidobisabolenes (14–16). Their structures were determined on the basis of extensive NMR and mass spectroscopic analyses in association with ICD data, Mosher reaction and chemical conversion for the assignment of absolute configurations. All compounds were evaluated for antitumor and antimicrobial activities.     

Halichonadins A-D, new sesquiterpenoids from a sponge Halichondria sp.

A new dimeric sesquiterpenoid with two eudesmane skeletons through a urea linkage, halichonadin A (1), as well as three new eudesmane sesquiterpenoids having a carbamate, an isonitrile, or an amino functionality, halichonadins B (2), C (3), and D (4), respectively, have been isolated from a marine sponge Halichondria sp., and the gross structures and relative stereochemistry of 1-4 were elucidated on the basis of spectral data and chemical means.     

Hapalocyclamide: a novel phytotoxic hexapeptide of the cyanobacterium Hapalosiphon sp.

Hapalocyclamide, a novel oxazole-, thiazole- and thiazoline-containing cyclic hexapeptide, was isolated from the terrestrial cyanobacterium Hapalosiphon sp., and which showed phytotoxic activity on lettuce seedling growth. The gross structure of hapalocyclamide was established from spectroscopic data and chemical degradation. The absolute stereochemistry was determined by Marfey’s analysis. Hapalocyclamide was established as cyclo-thiazole-l-alanine-oxazole-d-alanine-d-thiazoline-d-phenylalanine.     

Chaetominedione, a new tyrosine kinase inhibitor isolated from the algicolous marine fungus Chaetomium sp.

A marine fungal isolate, identified as Chaetomium sp., was cultivated and found to produce a novel benzonaphthyridinedione derivative, chaetominedione (1). In addition to the known fungal metabolites, 2-furancarboxylic acid (2) and 5-(hydroxymethyl)-2-furancarboxylic acid (3) were obtained. The structures of all the compounds were determined based on extensive spectroscopic measurements (1D and 2D NMR, MS, UV, and IR). The total extract and compound 1 had significant inhibitory activity toward p56^lck tyrosine kinase (18.7% and 93.6% enzyme inhibition at 200 μg/mL, respectively).     

Halichonadins G-J, new sesquiterpenoids from a sponge Halichondria sp.

Three new dimeric sesquiterpenoids, halichonadins G-I (1-3), and one new eudesmane sesquiterpenoid possessing a 1-phenethyl urea moiety, halichonadin J (4), were isolated from a marine sponge Halichondria sp. Halichonadins G (1) and H (2) are homo-dimers of eudesmane sesquiterpenoid, linked through a methyl 2-{1-(2-amino-2-oxoethyl)ureido}acetate fragment and a 2-hydroxymalonamide fragment, respectively, while halichonadin I (3) is a new hetero-dimer of eudesmane sesquiterpenoid linked through a urea fragment. The structures of 1-4 were elucidated on the basis of spectroscopic data.     

Prorocentin-4, a novel linear polyketide from a marine dinoflagellate Prorocentrum sp.

Prorocentin-4, isolated from a cultured marine dinoflagellate Prorocentrum sp. was possessed of two tetrahydrofuran rings, conjugated dienes, four branched methyl groups, and a ketone moiety. The gross structure was elucidated by spectroscopic studies and the relative stereostructure was determined on the basis of spectral data.     

Amphezonol A, a novel polyhydroxyl metabolite from marine dinoflagellate Amphidinium sp.

Amphezonol A (1), a novel polyhydroxyl linear carbon-chain metabolite, has been isolated from the cultured marine dinoflagellate Amphidinium sp., which was isolated from an Okinawan marine acoel flatworm Amphiscolops sp. The structure of 1 was elucidated by detailed analyses of 2D NMR spectra. Amphezonol A (1) possesses one tetrahydrofuran ring, two tetrahydropyran rings, and twenty-one hydroxyl groups on C₆₀-linear aliphatic chain with one exo-methylene and one methyl branch. Amphezonol A (1) exhibited a modest inhibitory activity against DNA polymerase α.     

Untenolide A, a new polyketide from an Okinawan marine sponge Plakortis sp.

A new polyketide, untenolide A (1), has been isolated from an Okinawan marine sponge Plakortis species, and the structure was elucidated from spectroscopic data and X-ray analysis. Untenolide A (1) is a new polyketide possessing a fused-pentacyclic skeleton with two hexadecanyl chains.     

Benzosceptrin C, a new dimeric bromopyrrole alkaloid from sponge Agelas sp.

A new dimeric bromopyrrole alkaloid possessing a benzocyclobutane ring, benzosceptrin C (1), has been isolated from an Okinawan marine sponge of the genus Agelas (SS-956), and the structure and relative stereochemistry were elucidated from spectroscopic data. Benzosceptrin C (1) showed antimicrobial activity.     

New alkaloids and diterpenes from a deep ocean sediment derived fungus Penicillium sp.

Four new alkaloids, including two new meleagrin analogs, meleagrins B (2) and C (3), and two new diketopiperazines, roquefortines F (5) and G (6), together with six new diterpenes, conidiogenones B-G (7-12), were isolated from a deep ocean sediment derived fungus Penicillium sp. The structures and stereochemistry of the new compounds were elucidated by spectroscopic methods. The cytotoxicity of the new compounds against the HL-60, A-549, BEL-7402, and MOLT-4 cell lines was evaluated.     

Plakoridine C, a novel piperidine alkaloid from an Okinawan marine sponge Plakortis sp.

A new piperidine alkaloid plakoridine C (1) has been isolated from an Okinawan marine sponge Plakortis species, and the structure was elucidated from spectroscopic data. Plakoridine C (1) is a new alkaloid possessing a piperidine ring connected to a β-keto-γ-lactone through a double bond.     

Banchromene and other secondary metabolites from the endophytic fungus Fusarium sp. obtained from Piper guineense inhibit the motility of phytopathogenic Plasmopara viticola zoospores

A new chromene, (S)-banchromene (1), together with seven known compounds, ergosterol, beauvericin (2), fusaproliferin (3), radicinin (4), poly(3-hydroxybutyric acid) (PHB, 5), N-methylpyrrolidone and an inseparable mixture of isochromene derivatives 6a, 6b, were isolated from a culture of Fusarium sp. strain CAMKT24b1, an endophytic fungus from the leaves and twigs of Piper guineense (Piperaceae). The structures of these metabolites were elucidated on the basis of their spectroscopic data; the absolute configuration of 1 was determined by ab initio-calculation of the optical rotation. In tests with the zoospores of the grapevine downy mildew pathogen Plasmopara viticola, compounds 1–4 showed moderate to high levels of motility-impairing activity at concentrations as low as 2.5 μg/mL. Compound 2 was the most active, exhibiting both motility-halting and lytic activities. Furthermore, compounds 2 and 3 displayed significant cytotoxic activity against brine shrimp larvae (Artemia salina) at 10 μg/mL. This is the first report on motility inhibitory and lytic activities of metabolites from an endophytic Fusarium species against the zoospores of the downy mildew pathogen P. viticola.     

Dihydroisocoumarin derivatives with antifouling activities from a gorgonian-derived Eurotium sp. fungus

Five pairs of new dihydroisocoumarin enantiomers, (±)-eurotiumides A–E, and two related racemates, (±)-eurotiumides F and G, were isolated from a gorgonian-derived fungus, Eurotium sp. XS-200900E6. The enantiomeric separations for (±)-eurotiumides A–E were achieved by chiral-HPLC, and their absolute configurations were determined by ECD spectra. All of the isolated compounds are rare dihydroisocoumarin derivatives with a methoxy at C-4. (+)- And (−)-eurotiumides B and D with cis configurations of H-3/H-4 exhibited potent antifouling activities against the larval settlement of the barnacle Balanus amphitrite with the EC₅₀ values ranging from 0.7 to 2.3 μg/mL, and displayed high therapeutic ratios (LC₅₀/EC₅₀ >15). The tested compounds also showed extensive antibacterial activities. It was the first report of antifouling activities for dihydroisocoumarin derivatives.     

Trisorbicillinone A, a novel sorbicillin trimer, from a deep sea fungus, Phialocephala sp. FL30r

A novel sorbicillin trimer, trisorbicillinone A (1), was isolated from a deep sea fungus, Phialocephala sp. FL30r. The structure and relative stereochemistry of 1 were determined based on spectroscopic methods. Trisorbicillinone A (1) showed cytotoxicity against P388 and HL60 cells with the IC₅₀ value of 9.10 and 3.14 μM, respectively.     

Bromine-containing alkaloids from the marine sponge Penares sp.

Two new unusual alkaloids were isolated from the sponge Penares sp., collected from Viet Nam waters (the South China Sea). The structures of these compounds were established by analysis of 1D, 2D NMR (¹H-¹H COSY, DEPT, HSQC, HMBC, H2BC, and NOE), and MS data. Compound 1 shows moderate cytotoxicity against the human tumor cells HL-60 and HeLa.     

Lobozoanthamine, a new zoanthamine-type alkaloid from the Indonesian soft coral Lobophytum sp.

A new member of the family of zoanthamine-type alkaloids, lobozoanthamine (1), has been isolated from the Indonesian soft coral Lobophytum sp. This represents the first report of a zoanthamine-type alkaloid from a marine invertebrate different from zoanthids. The densely functionalized heptacyclic stereostructure of lobozoanthamine (1) has been established through the interpretation of 2D NMR data and application of the modified Mosher method.     

Antiplasmodial and antiviral cyclohexadepsipeptides from the endophytic fungus Pullularia sp. BCC 8613

Four new cyclohexadepsipeptides, pullularins A-D, were isolated from the endophytic fungus Pullularia sp. BCC 8613. Structures of these compounds were elucidated by interpretation of NMR spectroscopic and mass spectrometric data. The absolute configurations of amino acid and hydroxy acid residues were determined by HPLC analysis of depsipeptide acid hydrolyzates using a chiral column and Marfey's method. Pullularin A exhibited activities against the malarial parasite Plasmodium falciparum K1 (IC₅₀ 3.6 μg/mL) and herpes simplex virus type 1 (HSV-1; IC₅₀ 3.3 μg/mL), whereas it showed weak cytotoxicity to Vero cells (IC₅₀ 36 μg/mL).     

Biverlactones A-D, new circumventors of arbekacin resistance in MRSA, produced by Penicillium sp. FKI-4429

Biverlactones, new circumventors of arbekacin resistance in methicillin-resistant Staphylococcus aureus (MRSA) were isolated from a culture broth of Penicillium sp. FKI-4429. Their structures were elucidated by spectroscopic studies, including various NMR experiments. Biverlactones A-D had novel skeletons, consisting of a lactone ring conjugated with exo- or endo-olefin, a carboxylic group and a characteristic alkyl side chain in common.     

Lyngbyacyclamides A and B, novel cytotoxic peptides from marine cyanobacteria Lyngbya sp.

Lyngbyacyclamides A (1) and B (2), novel cyclic peptides, were isolated from marine cyanobacteria Lyngbya sp. collected in Okinawa, Japan. Their structures were determined by spectroscopic analyses and degradation studies. They moderately inhibited the growth of B16 mouse melanoma cells.