A. I. Kalinovskii

Metabolites from the marine fungus Eurotium repens

Abstract1,8-Dihydroxy-6-methoxy-3-methyl-9,10-anthracenedione (physcion, 1), 3,4-dihydro-3,6,9-trihydroxy-8-methoxy-3-methyl-1(2H)-anthraceneone (asperflavin, 2), and 2,5-dihydroxy-3-(3-methyl-2-butenyl)-6-[(1E)-1-heptenyl]-benzaldehyde (tetrahydroauroglaucin, 3) were shown to be the main pigments of the marine isolate of the fungus Eurotium repens. In addition to the pigments, the fungal metabolites included the diketopiperazine alkaloid echinulin (4). The structures of the compounds were identified using NMR spectroscopy and mass spectrometry. The cytotoxic activity of 1–3 toward sex cells of the sea urchin Strongylocentrotus intermedius was determined.

Alkaloids from the Marine Isolate of the Fungus Aspergillus fumigatus

We previously isolated from the marine isolate of the fungus Aspergillus fumigatus KMM 4631 the five diketopiperazine antibiotics cyclotryprostatins A and B, fumitremorgin C, 12, 13-dihydrofumitremorgin C, and verruculogen [1]. Further research on metabolites of this strain afforded 1-5. Cultivation was performed under the previously described conditions [1]. The CHCl 3: 2H5OH extract of A. fumigatus was chromatographed over a column of silica gel L (40/100 μm) with elution successively by CHCl 3 and CHCl 3:C2H5OH (10:1 and 5:1). Fractions eluted by CHCl 3:C2H5OH (10:1) were combined, concentrated in vacuum to the minimal volume, and separated by HPLC over columns of Silasorb Si (ethylacetate:hexane, 4:1) and Diasphere-110-C18 (from 50 to 60% CH 3OH in water) to afford 1 (4 mg), 2 (18 mg), 3 (3 mg), 4 (3.5 mg), and 5 (4 mg).

Fumitremorgins from the marine isolate of the fungus Aspergillus fumigatus

Marine fungi are a rich source of biologically active compounds of various nature [1, 2]. In continuation of research on secondary metabolites from marine-fungus isolates, we investigated the strain A pergillus fumigatus KMM 4631, which was isolated from a soft coral Simularia sp. (Kunashir island, Kuril islands, 52 m deep). It has been demonstrated that this strain produces during cultivation on modified rice medium [3] for 21 days compounds that inhibit the growth of gram-positive bacteria and exhibit cytotoxic activity toward Erlich carcinoma tumor cells. The cultivation was carried out at 22 °C in 20 Ehrlenmeyer flasks (500 mL) containing rice (20 g), yeast extract (20 mg), KH2PO4 (10 mg), and natural seawater (40 mL). The mycelium together with the medium was ground and extracted three times with CHCl 3:alcohol (2:1). The extract was evaporated. The solid was chromatographed over a column of silica gel L (40/100 μm) with elution successively by CHCl 3 and CHCl 3:alcohol (10:1 and 5:1). Fractions eluted by CHCl 3:alcohol (10:1) were combined, concentrated in vacuum to the minimal volume, and separated by HPLC over Silasorb Si (ethylacetate:hexane, 4:1) and Diaspher-110-C18 (55% MeOH) columns to afford 1 (48 mg), 2 (42 mg), 3 (36 mg), 4 (56 mg), and 5 (40 mg).

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).

Secondary metabolites of the Vietnamese nudibranch mollusk Phyllidiella pustulosa

The chemical composition of the EtOH extract of the nudibranch mollusk Phyllidiella pustulosa was studied. Six sesquiterpenoids including the novel secondary metabolite (+)-10(R)-isothiocyanoalloaromodendrane were isolated. The steroid composition of the extract was studied. The structures of three previously known ketosteroids and six sterols were identified.

Structure of psolusoside B — A nonholostane triterpene glycoside of the holothurian genus Psolus

The structure of psolusoside B — a minor triterpene oligoglycoside from the holothurianPsolus fabricii and the main glycoside fromPsolus sp. has been determined by the methods of partial acid hydrolysis, methylation,13C NMR, and FAB mass spectrometry as 20S-acetoxy-3β-{2′-O-[O-β-D-glucopyranosyl-(1 → 4)-O-β-D-glucopyranosyl]-4′-O-(6″-O-sulfato-β-D-glucopyranosyl)-β-D-xylo-pyranosyloxy}holosta-7,25-diene-18,16-carbolactone. 3β-[O-(3‴-O-Methyl-6‴-O-sulfato-β-D-glucopyranosyl)-(1 → 3)-O-(6″-O-sulfato-β-D-glucopyranosyl)-(1 → 4)-O-β-D-quinovopyranosyl-(1→2)-β-D-xylopyranosyloxy]holosta-9(11),25-dien-16-one (psolusoside A), known previously forPsolus fabricii, has been identified in a holothurian —Psolus sp. — from Kraternaya Bay (island of Ushishir).

METABOLITES OF THE MARINE FUNGUS Asperigillus varians KMM 4630

Microscopic marine fungi are rich sources of various biologically active compounds [1-3]. In searching for these compounds in fungi isolated frm various marine habitats, we observed that the ethylacetate extract of Aspergillus varians (Wehner) KMM 4630 culture medium contained compounds with antimicrobial activity. The fungus was isolated from the bottom of Aniva Bay (Sakhalin Island, 12 m). The evaporated extract was dissolved in ethanol (70%) and extracted with hexane. The aqueous alcohol part was evaporated to an aqueous solution that was extracted with butanol. The butanol extract (820 mg) was placed on polychrom-1. The aqueous effluent (550 mg) was evaporated. Then, the active fraction was chromatographed several times over silica gel using hexane:hexane-ethylacetate (15%). Thus, we isolated 1-3, which exhibited antimicrobial activity toward gram-positive and gram-negative bacteria.

Sulfated steroid glycosides from the Viet Namese starfish Linckia laevigata

Five sulfated steriodal compounds including one new glycoside called linckoside L7 (1) and four previously known glycosides 2–5 were isolated from the starfish Linckia laevigata. The structure sodium (22E, 24R)-3-O-(2-O-methyl-β-D-xylopyranosyl)-29-O-(β-D-xylopyranosyl)-24-ethylcholest-4,22-dien-3β,6β,8,15α,16β,29-hexaol 15-O-sulfate was proposed for L7. Linckoside L7 inhibited fertilization and egg-cell development in the sea urchin Strongylocentrotus intermedius.

Structure of ulososide A, a new triterpenoid glycoside from theUlosa sp. sponge

A new triterpenoid glycoside, (20S,22S,23R,24S)-3β,22,23-trihydroxy-3-O-[O-(β-D-glucuronopyranosyl)-(1→6)-(β-D-glucopyranosyl)]-14-nor-24-methyllanost-8(9)-en-31-oic acid (ulososide A), has been isolated from the sponge Ulosa sp. and characterized.

Structures of four new triterpene glycosides from the holothurian Cucumaria japonica

Four new triterpene glycosides of the holostane series have been isolated from an alcoholic extract of the economically important Pacific Ocean holothurianCucumaria japonica: cucumariosides A1-2 (I), A2-3 (II), A2-4 (III), and A4-2 (IV). The structures of these substances have been established by the methods of carbohydrate chemistry and13C NMR spectroscopy.