New cerebrosides from the marine sponge Oceanapia sp.

New cerebrosides containing N-acetylglucosamine were isolated from the marine sponge Oceanapia sp. Some of them contain n-and iso-C₁₈-and iso-C₁₉-phytosphingosines N-acylated by n-C_16:0, n-C_17:0, and n-C_18:0 fatty acids, some other are derivatives of iso-and anteiso-C₁₇-,-C₁₈-, and-C₁₉-phytosphingosines N-acylated by long-chain (C₂₄-C²⁸) α-hydroxy acids. The structures of these compounds were determined by NMR spectroscopy, MALDI-TOF mass spectrometry, and by chemical transformations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 895–899, May, 2006.     

Callyptide A,a new cytotoxic peptide from the Red Sea marine sponge Callyspongia species

In the course of our continuing efforts to allocate bioactive secondary metabolites from Red Sea marine invertebrates, we have investigated the sponge Callyspongia species. The cytotoxic dichloromethane fraction of the methanolic extract of the sponge afforded a new cytotoxic peptide named callyptide A (1). Its structure was determined by extensive 1D and 2D NMR (COSY, HSQC and HMBC) studies and high-resolution mass spectral determination. The configuration of the amino acids was determined by Marfey’s analysis. Callyptide A was found to exhibit growth inhibitory activity when tested against different cancer cell lines.     

New bromopyrrole alkaloids from the marine sponge Agelas sp.

Chemical investigation of the marine sponge Agelas sp. collected from the South China Sea resulted in the isolation of four new dimeric bromopyrrole alkaloids, including hexazosceptrin (1) with a rare cyclohexane-fused-cyclobutane skeleton, agelestes A and B (2–3), the sceptrin analogues without any aminoimidazole substitution, and (9S, 10R, 9′S, 10′R)-nakamuric acid (4), of which the absolute configuration was confirmed for the first time. The structure elucidation and absolute configuration assignments were unambiguously determined via extensive spectroscopic analyses and the comparison of experimental and calculated electronic circular dichroic spectra. Compounds 1 and 4 exhibited moderate antimicrobial activity.     

A new thiodiketopiperzaine from the marine sponge Tedania sp.

Abstract

A new thiodiketopiperzaine, tedanizaine A (1), together with six known ones, were isolated from the marine sponge Tedania sp. Their structures were determined by spectroscopic analyses. The absolute configuration of 1 was established by ECD calculation. Compound 1 was the second example of thiodiketopiperazine bearing a thiazolidine unit. Cytotoxic activities of 1 were also evaluated.     

New two-headed sphingolipid-like compounds from the marine sponge Oceanapia sp.

New two-headed sphingolipid-like compounds, rhizochalin B and rhizochalinin B, containing a butoxy group, which is rarely encountered in natural products, were isolated as peracetates from the marine sponge Oceanapia sp. Their structures were established by NMR spectroscopic and MALDI TOF and HRESI TOF MS methods. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 656–660, March, 2008.     

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.     

Nitrogenous sesquiterpenes from the Thai marine sponge Halichondria sp.

Five nitrogenous sesquiterpenes having an isonitrile [(−)-axisonitrile-3], a formamide [(+)-axamide-3, axamide-2 and (3S^*,5R^*,6R^*,9R^*)-3-formamido-1(10)-cadinene], and an amine [(−)-halichamine] functionality were isolated from the Thai marine sponge Halichondria sp., together with two steroids, ergosterol and ergosterol peroxide. (−)-Axisonitrile-3 was isolated from the natural source for the first time, while (+)-axamide-3 and (−)-halichamine were new metabolites. The structures of these compounds were elucidated on the basis of their spectroscopic data and by chemical transformations. All sesquiterpenes were tested for their cytotoxic activity against six cancer cell lines (HeLa, HuCCA-1, A549, MOLT-3, HepG2, MDA-MB231). Only (−)-axisonitrile-3 showed strong activity to the HepG2 cell line with an IC₅₀ value of 1.3 μM.     

Heteroaromatic alkaloids,nakijinamines, from a sponge Suberites sp.

The structures of seven new secondary metabolites isolated from an Okinawan marine sponge Suberites sp., nakijinamines A (1), B (2), and F–I (3–6) and 6-bromoconicamin (7), have been elucidated on the basis of spectroscopic analysis, chemical conversion, and conformational analysis. These analyses disclosed that 1–6 were heteroaromatic alkaloids having the hybrid structures of an aaptamine-type alkaloid and an indole alkaloid, while 7 was a bromoindole alkaloid. Nakijinamine I (6) is the first example of an aaptamine-type alkaloid possessing a 1,4-dioxane ring. Antimicrobial activities of 1–7 were evaluated.     

Avarol and isoavarol from a Pacific Ocean sponge Dysidea sp.

Two hydroquinone-group-containing terpenoids have been isolated from a Pacific Ocean spongeDysidia, sp. One of them has been identified by physicochemical methods as the previously known avarol. The second, isoavarol, obtained for the first time, differs from avarol by the 4(11)-position of the double bond.     

Isolation and synthesis of N-acyladenine and adenosine alkaloids from a southern Australian marine sponge, Phoriospongia sp.

Chemical fractionation of the southern Australian marine sponge Phoriospongia sp. (CMB-03107) yielded phorioadenine A (1) as a nematocidal agent and the first reported example of a 6-N-acyladenine natural product. The structure of 1 was confirmed by spectroscopic analysis and the chemical synthesis of racemic (1a) and enantiomeric (1b) analogues. HPLC–ESIMS analysis of the crude sponge extract with comparisons to the synthetic 6-N-acyladenosine 2a provided evidence that the biosynthetically related adenosine, phorioadenosine A (2), was present as a trace co-metabolite. The rare starfish metabolite asterubine (3) was also isolated as a co-metabolite, and its structure confirmed by spectroscopic analysis and chemical synthesis. Biological investigations confirmed that natural products 1–3 and synthetic analogues 1a–e and 2a were not cytotoxic to multiple mammalian cancer cell lines, or Gram-positive or -negative bacteria. Nematocidal activity (inhibition of larval development of Haemonchus contortus) detected in the Phoriospongia sp. extract was attributed to 1 (LD₉₉ 31 μg/mL), with preliminary structure–activity relationship investigations confirming the importance of the N-acyl side chain.     

Dysamide U,a new trichlorinated diketopiperazine from the sponge Dysidea sp.

Dysamide U,a new tricblorinated diketopiperanne(1)along with seven known ones(2-8)were isolated from the sponge of Dysidea sp.collected from the Pacific ocean.The structure of dysamide U(1)was elucidated by high resolution FARMS and 1H NMR data induding COSY and RCT-COSY.     

Novel sulfated sesterterpene alkaloids from the marine sponge Fasciospongia sp

Fasciospongines A (1) and B (2), two unusual sulfated sesterterpene alkaloids of an unprecedented structural class, have been isolated from the marine sponge Fasciospongia sp. The structures were elucidated on the basis of spectroscopic analysis. Compounds 1 and 2 displayed potent inhibitory activity to Streptomyces 85E in the hypha formation inhibition (HFI) bioassay.     

Manzamine B and C,two novel alkaloids from the sponge haliclona sp.

The title compounds were isolated from a marine sponge collected off Okinawa. Their structures were determined by X-ray and shown to be 1-β-carbolines. Manzamine C was the 2-ethyl-N-azacycloundec-6-ene derivative, whereas manzamine B was more complex being the epoxy isomer of the free base of dihydromanzamine A.     

Three new aaptamines from the marine sponge Aaptos sp. and their proapoptotic properties

Three new aaptamine-type alkaloids, 2,3-dihydro-2,3-dioxoaaptamine (1), 6-(N-morpholinyl)-4,5-dihydro-5-oxo-demethyl(oxy)aaptamine (2) and 3-(methylamino)demethyl(oxy)aaptamine (3), along with known aaptamines were isolated from the sponge Aaptos sp. Their structures were determined on the basis of detailed analysis of their 1D and 2D NMR spectroscopic and mass spectral data. The isolated compounds induced apoptosis in human leukemia THP-1 cells.     

Xestosaprol D and E from the Indonesian marine sponge Xestospongia sp.

Chemical investigation of an extract of the marine sponge Xestospongia yielded a suite of pentacyclic compounds, including two new xestosaprol derivatives. Xestosaprol D (1) and E (2) are regioisomers, whose structures were defined through analysis of spectroscopic data.