Vladimir B. Krasokhin

Monanchocidin: A New Apoptosis-Inducing Polycyclic Guanidine Alkaloid from the Marine Sponge Monanchora pulchra

Monanchocidin (1), a guanidine alkaloid with an unprecedented skeleton system derived from a polyketide precursor, (ω-3)-hydroxy fatty acid, and containing a 2-aminoethyl- and 3-aminopropyl-substituted morpholine hemiketal ring, has been isolated from the sponge Monanhora pulchra. The structure of 1 was assigned on the basis of detailed analysis of 1D and 2D NMR spectra, mass spectrometry, and results of chemical transformations. Compound 1 shows pro-apoptotic and cytoxic activities.

Sterols from six marine sponges

The free sterol fractions from marine sponges Darwinella australiensis, Haliclona sp., Agelas mauritiana, Clathria major, Didiscus aceratusand Teichaxinella labirinticafrom Western Australia were isolated and studied by HPLC, GLC, GLC-MS, and NMR methods. D. australiensis contained 7 -, 5 -, 5,7 -, 5,7,9(11) -sterols, and cholest-7-en-3β-ol was shown to be a main sterol. The free sterols from A. mauritiana proved to be stanols and 7 -series compounds, chondrillasterol was identified as a predominant constituent. Haliclona sp. contained 5 -sterols with cholesterol as a main constituent. C. major and D. aceratus contained 5 -sterols, and clionasterol was shown to be a main sterol. T. labirintica was shown to contain 3β-hydroxymethyl-A-nor-sterols. Absolute configurations at C-24 of major sterols from C. major, D. aceratusand A. mauritiana were established by NMR method. Distribution of different sterols in the studied species was discussed to provide additional viewpoint on the probable application of these natural products as chemotaxonomic markers and to understand biological roles of unusual sterols in sponges using an idea of so-called biochemical coordination.  2003 Elsevier Ltd. All rights reserved.

Glycosides from marine sponges (Porifera, Demospongiae): structures, taxonomical distribution, biological activities and biological roles.

Literature data about glycosides from sponges (Porifera, Demospongiae) are reviewed. Structural diversity, biological activities, taxonomic distribution and biological functions of these natural products are discussed.

Sesquiterpenoid aminoquinones from the marine sponge Dysidea sp.

Four new sesquiterpenoid arenarone derivatives, 18-aminoarenarone (1), 19-aminoarenarone (2), 18-methylaminoarenarone (3), and 19-methylaminoarenarone (4), and the new dimeric popolohuanone F (5), a derivative of 19-aminoarenarone (2) and arenarol (6), have been isolated from the Australian marine sponge Dysidea sp. together with the known compounds arenarol (6) and popolohuanone A (7). The structures of the new compounds 1-5 were established from extensive NMR spectroscopic data. Popolohuanones A (7) and F (5) and arenarol (6) showed DPPH radical scavenging activity with IC(50) values of 35, 35, and 19 microM, respectively.

Silicatein genes in spicule-forming and nonspicule-forming Pacific demosponges.

Silicatein genes are known to be involved in siliceous spicule formation in marine sponges. Proteins encoded by these genes, silicateins, were recently proposed for nanobiotechnological applications. We studied silicatein genes of marine sponges Latrunculia oparinae collected in the west Pacific region, shelf of Kuril Islands. Five silicatein genes, LoSilA1, LoSilA1a, LoSilA2, and LoSilA3 (silicatein-α group), LoSilB (silicatein-β group), and one cathepsin gene, LoCath, were isolated from the sponge L. oparinae for the first time. The deduced amino acid sequence of L. oparinae silicateins showed high-sequence identity with silicateins described previously. LoCath contains the catalytic triad of amino acid residues Cys-His-Asn characteristic for cathepsins as well as motifs typical for silicateins. A phylogenetic analysis places LoCath between sponge silicateins-β and L-cathepsins suggesting that the LoCath gene represents an intermediate form between silicatein and cathepsin genes. Additionally, we identified, for the first time, silicatein genes (AcSilA and AcSilB) in nonspicule-forming marine sponge, Acаnthodendrilla sp. The results suggest that silicateins could participate also in the function(s) unrelated to spiculogenesis.

Occurrence of a Silicatein Gene in Glass Sponges (Hexactinellida: Porifera)

Silicatein genes are involved in spicule formation in demosponges (Demospongiae: Porifera). However, numerous attempts to isolate silicatein genes from glass sponges (Hexactinellida: Porifera) resulted in a limited success. In the present investigation, we performed analysis of potential silicatein/cathepsin transcripts in three different species of glass sponges (Pheronema raphanus, Aulosaccus schulzei, and Bathydorus levis). In total, 472 clones of such transcripts have been analyzed. Most of them represent cathepsin transcripts and only three clones have been found to represent transcripts, which can be related to silicateins. Silicatein transcripts were identified in A. schulzei (Hexactinellida; Lyssacinosida; Rosselidae), and the corresponding gene was called AuSil-Hexa. Expression of AuSil-Hexa in A. schulzei was confirmed by real-time PCR. Comparative sequence analysis indicates high sequence identity of the A. schulzei silicatein with demosponge silicateins described previously. A phylogenetic analysis indicates that the AuSil-Hexa protein belongs to silicateins. However, the AuSil-Hexa protein contains a catalytic cysteine instead of the conventional serine.

New polar steroids from the sponges Trachyopsis halichondroides and Cymbastela coralliophila

Fractions of trisulfated trihydroxysteroids from the sponges Trachyopsis halichondroides (two different collections) and Cymbastela coralliophila have been isolated and investigated. Ten triacetates were obtained from these fractions by desulfatation/acetylation followed by chromatographic separation, and their structures have been established. Four of these derivatives--namely, triacetates of 5 alpha-pregnane-2 beta,3 alpha,6 alpha-triol (3c), 23,24-dinor-5 alpha-cholane-2 beta,3 alpha,6 alpha-triol (4c), 5 alpha-cholest-22-ene-2 beta,3 alpha,6 alpha-triol (7c), and 24-isopropyl-5 alpha-cholestane-2 beta,3 alpha,6 alpha-triol (11c)-- are described as new derivatives of natural steroids.

Melonoside A: An ω-Glycosylated Fatty Acid Amide from the Far Eastern Marine Sponge Melonanchora kobjakovae

Melonoside A (1), the first representative of a new class of ω-glycosylated fatty acid amides, was isolated from the Far Eastern marine sponge Melonanchora kobjakovae. The structure of 1, including absolute configuration, was established using detailed analysis of 1D and 2D NMR, CD, and mass spectra as well as chemical transformations. Compound 1 induces autophagy of human cisplatin-resistant germinal tumor cells NCCIT-R.

New ceramides from sea sponge Oceanapia sp.

Total ceramides containing nonbranched and iso-branched C18-and C19-phytosphingosines acylated with nonhydroxylated fatty acids were isolated from a marine sponge Oceanapia sp. The structures of these compounds were determined by HPLC, NMR, MALDI TOF MS, and GLC-MS of the Me3Si derivatives and by chemical transformations.

The Extracts of Some Marine Invertebrates and Algae Collected off the Coast Waters of Vietnam Induce the Inhibitory Effects on the Activator Protein-1 Transcriptional Activity in JB6 Cl41 Cells

It has previously been shown that inhibition of the transcriptional activity of the oncogenic nuclear factor AP-1 can result in cancer prevention. Marine invertebrates and alga are a rich source of natural compounds that possess various biological activities. The inhibitory effects of the extracts of Vietnamese marine organisms in relation to the AP-1 transcriptional activity were examined by the luciferase method using JB6 Cl41 cells stably expressing a luciferase reporter gene controlled by AP-1 DNA binding sequence. As was found, 71 species of marine sponges out of 148 species studied contain inhibitors of the AP-1 transcriptional activity. Therefore, marine organisms as a source of biologically active compounds have a great potential for isolation of the new cancer preventive compounds that inhibit the oncogenic AP-1 nuclear factor.