Nobutoshi Ojima

New butenolides from Aspergillus terreus

Abstract From the culture filtrate of Aspergillus terreus , seven related yellow substances were isolated and the simplest, C 17 H 12 O 5 , was proved to be 3-( p -hydroxyphenyl)-4-hydroxy-5-( p -hydroxybenzylidene)-2(5H)-furanone.

Solute partition study in aqueous sodium dodecyl sulfate micellar solutions for some organic reagents and metal chelates

The partition constants (Kd) have been estimated for nitrophenols, thiazolylazo dyestuffs and metal chelate compounds into the sodium dodecyl sulfate (SDS) micellar phase at an ionic strength of 0.10M [(H+, Na+)Cl−] and at 20 °C. The equilibrium partition data obtained by batch-wise solution spectrophotometry (equilibrium shift method) agree well with those by the micellar electrokinetic capillary chromatography (MECC) with the SDS micellar pseudo-stationary phase. The MECC clearly discriminates a very small difference (0.03) in the logKd values of some metal chelates. The plot of theKd values with the van der Waals volume of the solute molecules obviously shows the leveling-off of theKd values over solute size near 110 ml/mol, which seems to be consistent with the results obtained in the Triton X-100 micellar system. This phenomenon arises most probably from the rigidity of the micellar pseudo-phase (a micellar volume-constraint effect) in sharp contrast with true two-phase partitioning such as solvent extraction systems.

Structures of pulvinone derivatives from Aspergillus terreus

Abstract The structures were established of six pulvinone derivatives, together with 3-(p-hydroxyphenyl)-4-hydroxy-5-(p-hydroxybenzylidene)-2(5H)-furanone (dihydroxy pulvinone), which were all isolated from a culture of Aspergillus terreus. Dihydroxy pulvinone is the fundamental structure for the six new compounds, which have one more hydroxyl group and/or two 3,3-dimethylallyll or related groups substituted on the aryl nuclei.

[36] Aspulvinone dimethylallyltransferase

Publisher Summary This chapter focuses on synthesis of aspulvinone dimethylallyltransferase from mycelia of Aspergiilus terreus . The enzyme catalyzes the transfer of the dimethylallyl moiety from dimethylallyl pyrophosphate to activated positions ortho to the hydroxyl group of the two aromatic rings of aspulvinone E to give aspulvinone I (monoprenyl derivative) and aspulvinone H (diprenyl derivative) both of which are found as metabolites in A. terreus . The enzyme also catalyzes the prenylation of aspulvinone G, which is another metabolite of this series of pigments to give the corresponding prenylated product, aspulvinone J, which has not been found in the fungi but is assumed to be a precursor for aspulvinone C, D, and F. The principle and procedure of the assay method is described in the chapter. The prenylated product synthesized from aspulvinone E and dimethylallyl pyrophosphate, either one of which is radiolabeled, in the presence of enzyme is extracted with ether and assayed for radioactivity. Neither, aspulvinone E nor dimethylallyl pyrophosphate is extractable at neutral pH with ether. Aspulvinone E can be replaced by aspulvinone G which is also prenylated under the same conditions.

The isolation of 2,4-dihydroxy-3,6-dimethylbenzoic acid (3-methylorsellinic acid) from a culture of Aspergillus terreus

3-Methylorsellinic acid (3) was isolated from a culture of Aspergillus terreus; feeding experiment of radio-active precursors showed that formate was incorporated into (3), but not into orsellinic acid (1), suggesting that the methyl carbon at C-3 position was derived from formate.

Biosynthesis of pulvinone derivatives in Aspergillus terreus. Enzymatic prenylation of dihydroxypulvinone

The crude ammonium sulphate fraction of a cell-free extract from Aspergillus terreus catalysed the transfer of the C5 units from 3,3-dimethylallyl pyrophosphate (2) to both of the aryl rings of dihydroxypulvinone (1), giving a possible precursor of the meta-bolites (4) and (5).