Benzosceptrin C, a new dimeric bromopyrrole alkaloid from sponge Agelas sp.

A new dimeric bromopyrrole alkaloid possessing a benzocyclobutane ring, benzosceptrin C (1), has been isolated from an Okinawan marine sponge of the genus Agelas (SS-956), and the structure and relative stereochemistry were elucidated from spectroscopic data. Benzosceptrin C (1) showed antimicrobial activity.     

A New Virginae Butanolide from Streptomyces sp.

A novel butanolide, named virginaebutanolide F (1), was isolated from the lyophilized culture broth of Slreptomyces sp., along with a known compound virginaebutanolide C (2). Their structures including the stereochemistry were elucidated on the basis of extensive 1D and 2D NMR as well as HRESI-MS and CD spectroscopic analysis.     

Two new phenylspirodrimanes from the deep-sea derived fungus Stachybotrys sp. MCCC 3A00409

Two new phenylspirodrimanes, stachybotrin H (1) and stachybotrysin H (9) together with eleven known analogues (2–8, 10–13) were isolated from deep-sea derived Stachybotrys sp. MCCC 3A00409. Their structures were determined by extensive NMR data and mass spectroscopic analysis. Compounds 9–12 showed weak cytotoxicity against three human cancer cell lines K562, Hela and HL60 with IC₅₀ in the range of 18.5–52.8 μM.     

1H and 13C NMR assignments for two new steroids from the coral Chromonephthea sp.

Two new steroids isolated from EtOH extracts of the South China Sea soft coral Chromonephthea sp. were identified. One‐dimensional (1D) and two‐dimensional (2D) NMR experiments including COSY, HSQC, HMBC and NOESY were used for the determination of their structure. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis of new terpene derivatives via ruthenium catalysis: rearrangement of silylated enynes derived from terpenoids

Enyne rearrangement of silylated modified terpenoids has been used as the key step for the synthesis of new terpenes and terpenoids. The catalytic system generated in situ from [RuCl₂(p-cymene]₂, 1,3-bis(mesityl)imidazolinium chloride and cesium carbonate is able to perform the transformation of silylated 1,7-enynes into cyclic siloxanes. Selective cleavage of the silicon-carbon and silicon-oxygen bonds by simple reactions has been performed to afford new terpenes and terpenoids by formal addition of a C5 unit.     

Pompanopeptins A and B, new cyclic peptides from the marine cyanobacterium Lyngbya confervoides

A new 3-amino-6-hydroxy-2-piperidone (Ahp) containing peptolide, pompanopeptin A (1), and a novel N-methyl-2-amino-6-(4′-hydroxyphenyl)hexanoic acid (N-Me-Ahpha) containing cyclic pentapeptide connected with a sixth amino acid residue via a rare ureido linkage, pompanopeptin B (2), were isolated from the marine cyanobacterium Lyngbya confervoides collected from the southeastern coast of Florida. Their planar structures were determined by a combination of NMR spectroscopic analysis and mass spectrometry. The absolute configurations were established using advanced Marfey's method and chiral HPLC analysis of the chemical degradation products. Compound 1 selectively inhibited trypsin over elastase and chymotrypsin, with an IC₅₀ value of 2.4 μM; selectivity is conferred by an arginine residue in the cyclic core.     

Leucospilotaside C, a new sulfated triterpene glycoside from sea cucumber Holothuria leucospilota

A new triterpene glycoside, leueospilotaside C, along with two known saponin, was isolated from sea cucumber Holothuria leucospilota collected from the South China Sea, and its structure was elucidated as 3-O-{4'-O-sodiumsulfate-β-D-xylopyranosyl }-holosta-22,25-epoxy-9-ene-3β, 12a, 17a-triol (1) by extensive spectroscopic analysis and chemical methods. The glycosides have the same triterpene aglycone, but differ in the oligosaccharide moieties.     

Separation,Purification, Structural Characterization,and Anticancer Activity of a Novel Exopolysaccharide from Mucor sp.

Mucor sp. has a wide range of applications in the food fermentation industry. In this study, a novel exopolysaccharide, labeled MSEPS, was separated from Mucor sp. fermentation broth through ethanol precipitation and was purified by ion-exchange chromatography, as well as gel filtration column chromatography. MSEPS was composed mostly of mannose, galactose, fucose, arabinose, and glucose with a molar ratio of 0.466:0.169:0.139:0.126:0.015 and had a molecular weight of 7.78 × 10⁴ Da. The analysis of methylation and nuclear magnetic resonance results indicated that MSEPS mainly consisted of a backbone of →3,6)-α-d-Manp-(1→3,6)-β-d-Galp-(1→, with substitution at O-3 of →6)-α-d-Manp-(1→ and →6)-β-d-Galp-(1→ by terminal α-l-Araf residues. MTT assays showed that MSEPS was nontoxic in normal cells (HK-2 cells) and inhibited the proliferation of carcinoma cells (SGC-7901 cells). Additionally, morphological analysis and flow cytometry experiments indicated that MSEPS promoted SGC-7901 cell death via apoptosis. Therefore, MSEPS from Mucor sp. can be developed as a potential antitumor agent.     

A new C27-steroidal glycoside from Ophiopogon japonicus

A new C27-steroidal glycoside with three known compounds were isolated from the tuber of Ophiopogonjaponicus （Thunb.） Ker-Gawl. Based on the spectral analysis, including HRMS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, HMQC and HMBC, their chemical structures were determined as pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-xylopyranosyl-（1→ 4）-13-D-gluco- pyranoside （1）, pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-glucopyranoside （2）, ophiopojaponin C （3） and ophiopogonin D （4）. 2007 Jian Zhong Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.     

A new C21-steroidal glycoside from Cynanchum stauntonii

A new C21-steroidal glycoside with two known compounds were isolated from the root of Cynanchum Stauntonii.Based on thespectral analysis,including MS,1H NMR,13C NMR,DEPT,1H-1H COSY,13C-1H COSY,HMQC and HMBC,their chemicalstructures were determinated as glaucogenin-C 3-O-a-L-cymaropyranosyl-(1→4)-b-D-digitoxopyranosyl-(1→4)-β-D-canaropyranoside(1),stigmasterol(2)and ursolic acid(3).     

Plakoridine C, a novel piperidine alkaloid from an Okinawan marine sponge Plakortis sp.

A new piperidine alkaloid plakoridine C (1) has been isolated from an Okinawan marine sponge Plakortis species, and the structure was elucidated from spectroscopic data. Plakoridine C (1) is a new alkaloid possessing a piperidine ring connected to a β-keto-γ-lactone through a double bond.     

1H and 13C NMR assignments for two new xanthones from the endophytic fungus Xylaria sp. FRR 5657

The complete 1H and 13C NMR assignments are reported for the new natural products, 7-hydroxy-3-(hydroxymethyl)-1-methoxy-9H-xanthen-9-one (1) and 2,5-dihydroxy-8-methoxy-6-methyl-9-oxo-9H-xanthene -1-carboxylic acid (2). Both of these secondary metabolites were isolated from the fermentation culture of the endophytic fungus Xylaria sp. FRR 5657. 1D and 2D NMR experiments that included 1H, gCOSY, gHSQC and gHMBC were used for the determination of the structure and assignment of these xanthones.     

Pholiotone A,a new polyketide derivative from Pholiota sp

Abstract

Pholiotone A (1), a new polyketide derivative, with tetrahydrobenzofuran-4(2H)-one skeleton, together with four known compounds, trichodermatides A (2) and B (3) and koninginins B (4) and E (5), were isolated from the crude extract of Pholiota sp. The structures of all the isolated compounds were determined mainly by NMR experiments, the modified Mosher method and electronic circular dichroism (ECD) calculations. The antifungal and cytotoxicity of all isolates were evaluated.     

Evidence for the intermediacy of arylbenzylnitrenium ions in the thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile

In contrast to the diaryl, dialkyl, alkylaryl, and parent series, nothing is known about the generation and chemical behavior of arylbenzylnitrenium ions. Herein, we report that these species can be generated by a process involving an unprecedented thermal rearrangement of isoxazolidines derived from C,N-diarylnitrones and 2-morpholin-4-yl-acrylonitrile. The products from these reactions are dramatically dependent upon the nature of the nitrone. Most of the observed chemistry originates from the singlet state.     

Lanthanide complexes of new nonadentate imino-phosphonate ligands derived from 1,4,7-triazacyclononane: synthesis, structural characterisation and NMR studies

The polyamino ligand 1,4,7-tris(2-aminoethyl)-1,4,7-triazacyclononane (1) has been used to synthesise two new ligands by Schiff-base condensation with methyl sodium acetyl phosphonate to give ligand L and methyl sodium 4-methoxybenzoyl phosphonate to give ligand L1 in the presence of lanthanide ion as templating agent to form the complexes [Ln(L)] and [Ln(L1)](Ln = Y, La, Gd, Yb). Both ligands L and L1 have nine donor atoms comprising three amine and three imine N-donors and three phosphonate O-donors and form Ln(III) complexes in which the three pendant arms of the ligands wrap around the nine-coordinate Ln(III) centres. Complexes with Y(III), La(III), Gd(III) and Yb(III) have been synthesised and the complexes [Y(L)], [Gd(L)] and [Gd(L1)] have been structurally characterised. In all the complexes the coordination polyhedron about the lanthanide centre is slightly distorted tricapped trigonal prismatic with the two triangular faces of the prism formed by the macrocyclic N-donors and the phosphonate O-donors. Interestingly, given the three chiral phosphorus centres present in [Ln(L)] and [Ln(L1)] complexes, the three crystal structures reported show the presence of only one diastereomer of the four possible. 1H, 13C and 31P NMR spectroscopic studies on diamagnetic [Y(L)] and [La(L)] and on paramagnetic [Yb(L)] complexes indicate the presence in solution of all the four different diastereomers in varying proportions. The stability of complexes [Y(L)] and [Y(L1)] in D2O in both neutral and acidic media, and the relaxivity of the Gd(III) complexes, have also been investigated.     

Diterpenes with new isoryanodane derived skeletons from Persea indica

A phytochemical study of the aerial parts of Persea indica has permitted the isolation of two diterpenes with novel skeletons derived from isoryanodane, which have named perseaindicol and secoperseanol. A third compound, also with a new carbon framework, proved to be identical with cinncassiol E, whose structure has been now corrected.     

Leucospilotaside C, a new sulfated triterpene glycoside from sea cucumber Holothuria leucospilota

A new triterpene glycoside, leucospilotaside C, along with two known saponin, was isolated from sea cucumber Holothuria leucospilota collected from the South China Sea, and its structure was elucidated as 3-0-{4′-O-sodiumsulfate-β′-D-xylopyranosyl}- holosta-22,25-epoxy-9-ene-3β,12α,17α-triol （1） by extensive spectroscopic analysis and chemical methods. The glycosides have the same triterpene aglycone, but differ in the oligosaccharide moieties.