Preparation and characterization of a novel extracellular polysaccharide with antioxidant activity, from the mangrove-associated fungus Fusarium oxysporum.

Marine fungi are recognized as an abundant source of extracellular polysaccharides with novel structures. Mangrove fungi constitute the second largest ecological group of the marine fungi, and many of them are new or inadequately described species and may produce extracellular polysaccharides with novel functions and structures that could be explored as a source of useful polymers. The mangrove-associated fungus Fusarium oxysporum produces an extracellular polysaccharide, Fw-1, when grown in potato dextrose-agar medium. The homogeneous Fw-1 was isolated from the fermented broth by a combination of ethanol precipitation, ion-exchange, and gel filtration chromatography. Chemical and spectroscopic analyses, including one- and two-dimensional nuclear magnetic resonance spectroscopies showed that Fw-1 consisted of galactose, glucose, and mannose in a molar ratio of 1.33:1.33:1.00, and its molecular weight was about 61.2 kDa. The structure of Fw-1 contains a backbone of (1 → 6)-linked ß-D-galactofuranose residues with multiple side chains. The branches consist of terminal α-D-glucopyranose residues, or short chains containing (1 → 2)-linked α-D-glucopyranose, (1 → 2)-linked ß-D-mannopyranose, and terminal ß-D-mannopyranose residues. The side chains are connected to C-2 of galactofuranose residues of backbone. The antioxidant activity of Fw-1 was evaluated with the scavenging abilities on hydroxyl, superoxide, and 1,1-diphenyl-2-picrylhydrazyl radicals in vitro, and the results indicated that Fw-1 possessed good antioxidant activity, especially the scavenging ability on hydroxyl radicals. The investigation demonstrated that Fw-1 is a novel galactofuranose-containing polysaccharide with different structural characteristics from extracellular polysaccharides from other marine microorganisms and could be a potential source of antioxidant.

2-Hydroxydiplopterol, a new cytotoxic pentacyclic triterpenoid from the halotolerant fungus Aspergillus variecolor B-17.

A new hopane type pentacyclic triterpenoid, 2-hydroxydiplopterol (1) has been isolated from the metabolites produced by the halotolerant fungal strain Aspergillus variecolor B-17. The structure of 1 was determined by spectroscopic methods and single crystal X-Ray diffraction analysis. 2-Hydroxydiplopterol (1) exhibited cytotoxicity against K562 cells with an IC50 value of 22 microM.

Cytotoxic and antioxidative phenolic compounds from the traditional Chinese medicinal plant, Myristica fragrans.

Two new phenolic compounds were isolated from the fruits of Myristica fragrans and their structures were elucidated as (-)-1-(2,6-dihydroxyphenyl)-9-[4-hydroxy-3-(p-menth-1-en-8-oxy)-phenyl]-1-nonanone ( 1) and (7 R,8 R)-7,8-dihydro-7-(3,4-dihydroxyphenyl)-3'-methoxy-8-methyl-1'-( E-propenyl)benzofuran (2). In addition, the absolute configuration of (+)-Delta8'-7-acetoxy-3,4,3',5'-tetramethoxy-8- O-4'-neolignan (3) was determined for the first time through spectroscopic and chemical methods. Their antioxidative activities against 2,2-diphenyl-1-picrylhydrazyl radical and cytotoxicity against K-562 cells were tested, and (7 S,8 S,7' R,8' S)-4,5'-dihydroxy-3,3'-dimethoxy-7,7'-epoxylignan (4) showed the corresponding activities with IC(50) values of 39.4 and 2.11 microM, respectively.

Cytotoxic macrocyclic diterpenoids from Euphorbia helioscopia.

A new cytotoxic macrocyclic diterpenoid, euphornin L (1), together with seven known analogues were isolated from the plant Euphorbia helioscopia L. The structure of 1 was elucidated by spectral data and X-ray crystallographic analysis. Euphornin L (1) and euphoscopin F (2) exhibited significant cytotoxicity against HL-60 cell lines with IC(50) values of 2.7 and 9.0 microM, respectively. The 13C-NMR data of euphoscopin F (2), epieuphoscopin B (3), euphoscopin B (5), and euphoscopin C (6) were also reported for the first time.

Three novel, structurally unique spirocyclic alkaloids from the halotolerant B-17 fungal strain of Aspergillus variecolor.

During our search for novel antitumor lead compounds from microorganisms living under extreme conditions, three novel alkaloids, variecolortides A-C (1-3), were isolated from the mycelia of the halotolerant fungal strain Aspergillus variecolor B-17. The new compounds were found to share an unprecedented 'spiro-anthronopyranoid diketopiperazine' structure, with a stable hemiaminal function, as corroborated by in-depth NMR-spectroscopic and mass-spectrometric analyses, as well as by a single-crystal X-ray analysis of 1. All compounds were shown to exhibit weak cytotoxic and antioxidant activities.

Isoechinulin-type alkaloids, variecolorins A-L, from halotolerant Aspergillus variecolor.

Twelve new compounds, variecolorins A-L ( 1- 12), together with eleven known analogues ( 13- 23) were isolated from the broth of a halotolerant fungus, Aspergillus variecolor. The structures of compounds 1- 12 were determined by chemical and spectroscopic methods. Compounds 1- 11, 13- 15, and 20- 23 exhibited weak radical scavenging activity against DPPH, with IC 50 values from 43 to 103 microM. The new compounds 1- 12 all were essentially nontoxic against the P388, HL-60, BEL-7402, and A-549 cell lines with IC 50 values from 70 to 260 microM.