O. F. Smetanina

Bromoalterochromides A and A', Unprecedented Chromopeptides from a Marine Pseudoalteromonas maricaloris Strain KMM 636^T

The marine strain Pseudoalteromonas maricaloris KMM 636T was found to produce an inseparable mixture of two brominated yellow main pigments, bromoalterochromide A and A′, in a ratio of 3 : 1. Both pigments are Thr-Val-Asn-Asn-X pentapeptide lactones, where the amino group of Thr is acylated with 9-(3-bromo-4-hydroxyphenyl)-nona-2,4,6,8-tetraenoic acid, and X is aIle and Leu, respectively. They possess cytotoxic effects on developing eggs of the sea urchin Strongylocentrotus intermedius, but no antibiotic activity.

Oxirapentyns F-K from the marine-sediment-derived fungus Isaria felina KMM 4639

Six new highly oxygenated chromene derivatives, oxirapentyns F-K (2-7), one new polyketide (8), one new benzofurane (9), and two known cyclodepsipeptides, isoisariin B and isaridin E, were isolated from the lipophilic extract of the marine-derived fungus Isaria felina KMM 4639. The structures of compounds 2-9 were determined using spectroscopic methods. The relative configurations of compounds 2-7 were established through a combination of NOE data and spin coupling constants, and these results were confirmed by X-ray crystallographic analysis of 4. The absolute structures of all oxirapentyns were assumed based on their biogenetic relationship and confirmed using the modified Moshers method on 2 and 7. Isariketide (8) showed moderate cytotoxicity toward HL-60 cells.

Decumbenone C, a new cytotoxic decaline derivative from the marine fungus Aspergillus sulphureus KMM 4640

A new decaline derivative, decumbenone C (1) along with four known compounds, decumbenones A (2) and B (3), diorcinol (4), and brevianamide F (5) were isolated from the marine fungus Aspergillus sulphureus KMM 4640. Decumbenone C shows potent cytotoxic activity against SK-MEL-5 human melanoma cells with IC50 values of 0.9 μM.

Controlling production of brominated cyclic depsipeptides by Pseudoalteromonas maricaloris KMM 636T

Aims:  This study aims at evaluating the impact of the nutrient medium components on the in vitro production of the cytotoxic alterochromides.

Metabolites of the marine fungus Humicola fuscoatra KMM 4629

A new sesquiterpene of the caryophyllene series, fuscoatrol A (1), and known compounds, 11-epiterpestacin (2) and β-nitropropionic acid (3), were isolated from the marine fungus Humicola fuscoatra (Traaen) KMM 4629 associated with the Kuril colonial ascidium. The structure of 1 was established on the basis of X-ray diffraction data and 2D NMR spectroscopy. The antimicrobial and cytotoxic activities of compounds 1–3 were studied.

Biologically active metabolites of the facultative marine fungus Penicillium citrinum

Four sesquiterpenoid metabolites, JBIR-27, petasol, sporogen AO-1, and dihydrosporogen AO-1, that were previously unknown for Penicillium citrinum were isolated from the marine isolate of this fungus. The structures of the compounds were established using NMR spectral data and high-resolution mass spectrometry. It was shown that sporogen AO-1 exhibited weak antimicrobial and cytotoxic properties. Cytotoxic action was observed for dihydrosporogen AO-1 against Ehrlich carcinoma cells (ED50 0.4 mM).

Pretrichodermamides D–F from a Marine Algicolous Fungus Penicillium sp. KMM 4672

Three new epidithiodiketopiperazines pretrichodermamides D–F (1–3), together with the known N-methylpretrichodermamide B (4) and pretrichodermamide С (5), were isolated from the lipophilic extract of the marine algae-derived fungus Penicillium sp. KMM 4672. The structures of compounds 1–5 were determined based on spectroscopic methods. The absolute configuration of pretrichodermamide D (1) was established by a combination of modified Mosher′s method, NOESY data, and biogenetic considerations. N-Methylpretrichodermamide B (5) showed strong cytotoxicity against 22Rv1 human prostate cancer cells resistant to androgen receptor targeted therapies.

Unique prostate cancer-toxic polyketides from marine sediment-derived fungus Isaria felina

Unique prostate cancer-toxic polyketides from marine sediment-derived fungus Isaria felina

Metabolites of the Marine Fungus Penicillium citrinum Associated with a Brown Alga Padina sp.

Fungi associated with marine algae are some of the most promising marine fungal producers. Greater than 10% of all new marine fungal metabolites were recently isolated from this ecological fungal class [1, 2]. We isolated the fungus Penicillium citrinum, which was identified using morphological signatures, from the surface of a brown alga Padina sp. (South China Sea, Vietnam coast) during a search for producers of new biologically active compounds among marine fungi associated with algae. The fungus was cultivated for 21 d at 22°C in 20 1-L Ehrlenmeyer flasks, each of which contained medium consisting of rice (10 g), sodium tartrate (0.005 g), yeast extract (0.01 g), KH2PO4 (0.005 g), and natural seawater (20 mL). Mycelium together with medium was extracted (2 ) with EtOAc. The extract was evaporated. The residue was dissolved in EtOH–H2O (1:4). The resulting solution was extracted sequentially with hexane, EtOAc, and BuOH. The EtOAc fraction developed a crystalline precipitate of 5 (500 mg). The mother liquor was evaporated at a reduced pressure. The obtained residue (2 g) was chromatographed over a column (25 2 cm) with silica gel using hexane–EtOAc with a stepwise gradient to 5%. The resulting fractions were rechromatographed over Sephadex LH-20 using EtOH–CHCl3 (1:1) to afford 1 (7.7 mg), 2 (2.2 mg), 3 (5.0 mg), and 4 (450.0 mg).

Asperpentyn from the Facultative Marine Fungus Curvularia inaequalis

Marine micromycete fungi are rich sources of new compounds that often exhibit strong biological activity. Fungi of the genus Curvularia were also described several times as producers of such compounds [1, 2]. The isolate of C. inaequalis, which was reported earlier by us as a producer of several known polyketides, was isolated during research on fungal metabolites from strains in the oceans of the Russian Far East [3]. Fungi were cultivated for 21 d in five 1-L Pyrex flasks, each of which contained medium consisting of malt extract (50 mL), agar (5 g), and seawater (200 mL). Mycelium together with medium was extracted twice with EtOAc. The extract was evaporated. The residue (0.4 g) was chromatographed over a column of silica gel (2 10 cm) with elution successively by hexane and hexane–EtOAc (stepwise gradient, 25:1 10:1). The fraction eluted by the 10:1 system (24 mg) was separated using HPLC over a ChiraDex chiral column and MeOH–H2O (40:60) to afford pure (–)-asperpentyn (1.5 mg).