New Deoxyisoaustamide Derivatives from the Coral-Derived Fungus Penicillium dimorphosporum KMM 4689.

Seven new deoxyisoaustamide derivatives (1-7) together with known compounds (8-10) were isolated from the coral-derived fungus Penicillium dimorphosporum KMM 4689. Their structures were established using spectroscopic methods, X-ray diffraction analysis and by comparison with related known compounds. The absolute configurations of some alkaloids were determined based on CD and NOESY data as well as biogenetic considerations. The cytotoxic and neuroprotective activities of some of the isolated compounds were examined and structure-activity relationships were pointed out. New deoxyisoaustamides 4-6 at concentration of 1 µM revealed a statistical increase of PQ(paraquat)-treated Neuro-2a cell viability by 30-39%.

Neuroprotective Metabolites from Vietnamese Marine Derived Fungi of Aspergillus and Penicillium Genera.

Low molecular weight secondary metabolites of marine fungi Aspergillus flocculosus, Aspergillus terreus and Penicillium sp. from Van Phong and Nha Trang Bays (Vietnam) were studied and a number of polyketides, bis-indole quinones and terpenoids were isolated. The structures of the isolated compounds were determined by 1D and 2D NMR and HR-ESI-MS techniques. Stereochemistry of some compounds was established based on ECD data. A chemical structure of asterriquinone F (6) was thoroughly described for the first time. Anthraquinone (13) was firstly obtained from a natural source. Neuroprotective influences of the isolated compounds against 6-OHDA, paraquat and rotenone toxicity were investigated. 4-Hydroxyscytalone (1), 4-hydroxy-6-dehydroxyscytalone (2) and demethylcitreoviranol (3) have shown significant increasing of paraquat- and rotenone-treated Neuro-2a cell viability and anti-ROS activity.

Biologically Active Echinulin-Related Indolediketopiperazines from the Marine Sediment-Derived Fungus Aspergillus niveoglaucus.

Seven known echinulin-related indolediketopiperazine alkaloids (1-7) were isolated from the Vietnamese sediment-derived fungus Aspergillus niveoglaucus. Using chiral HPLC, the enantiomers of cryptoechinuline B (1) were isolated as individual compounds for the first time. (+)-Cryptoechinuline B (1a) exhibited neuroprotective activity in 6-OHDA-, paraquat-, and rotenone-induced in vitro models of Parkinson's disease. (-)-Cryptoechinuline B (1b) and neoechinulin C (5) protected the neuronal cells against paraquat-induced damage in a Parkinson's disease model. Neoechinulin B (4) exhibited cytoprotective activity in a rotenone-induced model, and neoechinulin (7) showed activity in the 6-OHDA-induced model.

Erylosides F8, V1-V3, and W-W2 - New triterpene oligoglycosides from the Carribean sponge Erylus goffrilleri.

Seven new triterpene glycosides, erylosides F8 (1), V1 (2), V2 (3), V3 (4), W (5), W1 (6) and W2 (7), were isolated from a Carribean sponge Erylus goffrilleri collected from the Carribean Sea near the Arrecife-Seco reef (Cuba). Structures of the glycosides were determined using 1H and 13C NMR spectroscopy, including 2D NMR procedures (1H-1H COSY, 1H-13С HMBC, 1H-13С HSQC and NOESY) and HR ESI mass spectrometry. Erylosides 1 and 4 have 14-carboxy-24,25-dimethyllanost-8(9)-en-3ß,25-diol as aglycone whereas glycosides 2, 3, 5, 6 and 7 are 14-carboxy-24-acetoxy-24-methyllanost-8(9)-en-3ß-ol glycoconjugates. Cytotoxic activities of the isolated compounds against Ehrlich carcinoma cells and hemolysis were examined and their dependence on eryloside structure was evaluated.

New virescenosides from the marine-derived fungus Acremonium striatisporum.

Five new diterpene glycosides, virescenosides Z4-Z8 (1-5) have been isolated from a marine strain of Acremonium striatisporum KMM 4401 associated with the holothurian Eupentacta fraudatrix. Their structures were determined by HRESI-MS and 1D and 2D NMR. Virescenosides Z4-Z8 contain rare altruronic acid 4C1 and 1C4 conformations as their carbohydrate components. Virescenosides Z5 and Z7 exhibit an unusual 16-chloro, 15-hydroxyethylgroup as their side chains.

Determination of absolute stereochemistry of natural alicyclic glycosides by 1H NMR spectroscopy without application of chiral reagents--an indication.

A study has been made of the 1H NMR spectra of peracetylated beta-glucopyranosides and alpha-arabinopyranosides obtained by reaction of D- and L-glucoses, and L- and D-arabinoses with either (R)- or (S)-2-octanols. The obtained and literature data show that 1H NMR spectra may be used to determine the absolute configuration of the aglycone moieties of some alicyclic glycosides without the need to synthesize derivatives with chiral reagents, as long as the absolute configuration of their monosaccharide moiety is known or vice versa. Spectra of marine steroid glycosides and their acetates containing glycosylated side chains as alicyclic fragments were also examined. It was shown that analysis of 1H NMR spectra for the determination of the absolute configuration is more applicable in the cases when glycosides have the same substitution in the D-ring of the aglycone moiety.

Isolation and structures of erylosides from the Caribbean sponge Erylus formosus.

Nine new triterpene glycosides, erylosides F1-F4 (1-4), M (5), N (6), O (7), P (8), and Q (9), along with previously known erylosides F (10) and H (11) were isolated from the sponge Erylus formosus collected from the Mexican Gulf (Puerto Morelos, Mexico). Structures of 1-4 were determined as the corresponding biosides having aglycons related to penasterol with additional oxidation patterns in their side chains. Erylosides 5-9 contain new variants of carbohydrate chains with three (5, 6), four (7), and six (8, 9) sugar units, respectively. Erylosides 5, 7, 8, and 6, 9 contain 14-carboxy-24-methylenelanost-8(9)-en-3beta-ol and penasterol as aglycons, respectively. In contrast with its epimer 2, the compound 3 induced the early apoptosis of Ehrlich carcinoma cells at a concentration of 100 microg/mL, while 1 and 10 activated the Ca2+ influx into mouse spleenocytes (130% of the control) at the same doses.