Naoki Abe

Novel DPPH radical scavengers, bisorbicillinol and demethyltrichodimerol, from a fungus

In our screening program for antioxidants with DPPH radical scavenging activity, we isolated four yellowish compounds from the fermentation broth of Trichoderma sp. USF-2690 strain isolated from a soil sample: two were novel compounds designated bisorbicillinol (1) and demethyltrichodimerol (2), and two were known compounds bisvertinolone (3) and trichodimerol (4). The structures of 1 and 2 were elucidated by spectroscopic evidence and chemical modification. Two compounds seemed to be the oxidized dimers of sorbicillin. In the evaluation of DPPH radical scavenging activity, bisorbicillinol gave the lowest ED50 value (31.4 μM) among the four compounds, equal to that of BHT (27.0 μM).

DPPH Radical-Scavenging Compounds from Dou-Chi, a Soybean Fermented Food

Dou-chi, a traditional soybean food fermented with Aspergillus sp., is usually used as a seasoning in Chinese food, and has also been used as a folk medicine in China and Taiwan. As 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavengers, four phenol compounds, one isoflavanone, eight isoflavones and one 4-pyrone have been isolated from dou-chi. Among these fourteen compounds, 3′-hydroxydaidzein, dihydrodaidzein and a 4-pyrone compound have not yet been isolated from soybean miso. The structure of the novel 4-pyrone compound, 3-((E)-2-carboxyethenyl)-5-(4-hydroxyphenyl)-4-pyrone-2-carboxylic acid was elucidated by using the same compound as that obtained from the biotransformation of daidzein. 3′-Hydroxydaidzein showed as high DPPH radical-scavenging activity as that of α-tocopherol, and 6-hydroxydaidzein had mushroom tyrosinase inhibitory activity with an IC50 value of 10 μM. The order of estrogenic activity is as follows: genistein > daidzein >> 3′-hydroxydaidzein > 8-hydroxygenistein, using a green fluorescent protein expression system. Furthermore, the contents of isoflavones in the fermentation process of dou-chi were measured.

Studies on the 1,1-Diphenyl-2-picrylhydrazyl Radical Scavenging Mechanism for a 2-Pyrone Compound

The radical scavenging mechanisms for the 2-pyrone compound, 4-hydroxy-3,6-dimethyl-2H-pyrane-2-one (1), and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (4) in several solvent systems were evaluated by the quantitative change in compounds detected at 270 nm and subsequent HPLC analyses. The HPLC profile for each condition suggested that the reaction proceeded by a different mechanism in each solvent system. In organic solvents (CHCl3, iso-propanol, and EtOH), 1- [4-(3,4-dihydro-3,6-dimethyl-2,4-dioxo-2H-pyran-3-yl) phenyl]-1-phenyl-2-picrylhydrazine (2) was produced as an adduct of the DPPH radical and 1. On the other hand, the reaction in a buffer solution (an acetate buffer at pH 5.5) gave several degradation products with 1-[4-(2,3-dihydro-2,5-dimethyl-3-oxo-fur-2-yl) phenyl]-1-phenyl-2-picrylhydrazine (5), this being structurally elucidated by spectroscopic analyses. The decrease of the DPPH radical in each reaction system suggests that compound 1 could scavenge about 1.5-1.8 equivalents of the radical in organic solvents and about 3.5-3.9 in the buffer solution.

Novel Oxidized Sorbicillin Dimers with 1,1-Diphenyl-2-picrylhydrazyl-Radical Scavenging Activity from a Fungus

Three yellowish compounds with 1,1-diphenyl-2-picrylhydrazyl-radical scavenging activity were newly isolated from the fermentation broth of Trichoderma sp. USF-2690 strain that had been isolated from a soil sample: two were novel oxidized sorbicillin dimers designated as bisorbibutenolide (1) and bisorbicillinolide (2), and one was sorbicillin (3) itself. The structures of 1 and 2 were determined from spectroscopic evidence. In the DPPH-radical scavenging assay, α-tocopherol gave an ED50 value of 17.0 μM after standing for 30 min, while continuing observation showed that the ED50 values for bisorbibutenolide, bisorbicillinolide, and sorbicillin slowly reached 80.8, 88.8 and 152.3 μM over 24 hr.

Expeditious Synthesis of Vialinin B, an Extremely Potent Inhibitor of TNF-α Production

A first total synthesis of vialinin B, a powerful inhibitor (IC(50) 20 pM) of TNF-alpha production, is described. The key reactions include a double Suzuki-Miyaura coupling of electron-rich aryl bromide with a couple of phenylboronic acids, a Cu-mediated Ullmann reaction, and a LHMDS-promoted phenylacetylation. This synthesis proceeded in 11 steps with 18% overall yield from a known sesamol derivative.

Tetrapetalone A, a novel lipoxygenase inhibitor from Streptomyces sp

Abstract Tetrapetalone A ( I ), C 26 H 33 O 7 N, is a novel lipoxygenase inhibitor isolated from a culture filtrate of Streptomyces sp. USF-4727 strain. Its chemical structure was determined by its spectroscopic evidence and methylation with diazomethane. The stereochemistry was investigated by the coupling constant in 1 H NMR, NOESY data and modified Moshers method. I possessed a tetracyclic skeleton and a β-rhodinosyl moiety, and this is the first report of a compound with such a tetracyclic skeleton.

Isolation of 8-Hydroxyglycitein and 6-Hydroxydaidzein from Soybean Miso

We isolated from soybean miso 8-hydroxyglycitein and 6-hydroxydaidzein as DPPH-radical scavengers, and elucidated their chemical structures by mass spectrometric, and 1H- and 13C-NMR spectrosopic analyses. These compounds showed DPPH-radical scavenging activity as high as that of α-tocopherol, 8-hydroxygenistein and 8-hydroxydaidzein. This is the first report of the isolation of 8-hydroxyglycitein from a natural source.

Vialinin A, a Novel 2,2-Diphenyl-1-picrylhydrazyl (DPPH) Radical Scavenger from an Edible Mushroom in China

While screening for bioactive compounds from edible mushrooms, a new potent antioxidant, vialinin A (1), together with a known compound, ganbajunin B (2), and a mixture of ganbajunins D (3) and E (4), were isolated from the dry fruiting bodies of Thelephora vialis. The structure of 1, 5′,6′-bis(phenylacetoxy)-1,1′:4′,1″-terphenyl-2′,3′,4,4″-tetraol, was elucidated by spectroscopic and chemical methods. This compound had strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging activity with an EC50 value of 14.0 μM, nearly equal to that of butylated hydroxytoluene (BHT; EC50=10.0 μM). A radical scavenging experiment using 1 and DPPH radicals indicated that 1 donated two hydrogen atoms to two molecules of the DPPH radical under hydrophobic conditions.

Novel Lipoxygenase Inhibitors, Tetrapetalone B, C, and D from Streptomyces sp.

Three novel lipoxygenase inhibitors, tetrapetalone B (2, C28H35NO9), C (3, C26H34NO8), and D (4, C28H36NO10), were isolated from a culture broth of Streptomyces sp. USF-4727 that produced a lipoxygenase inhibitor tetrapetalone A (1) simultaneously. Each chemical structure was revealed by spectroscopic evidence, this suggests that these three compounds are structurally related to 1. They had a tetracyclic skeleton and a β-D-rhodinosyl moiety. Tetrapetalone B, C, and D inhibited soybean lipoxygenase with IC50: 320, 360, and 340 μM respectively.

Bisorbibetanone, a novel oxidized sorbicillin dimer, with 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity from a fungus

Abstract We isolated a novel oxidized sorbicillin dimer ( 1 ) as yellowish amorphous powder from the fermentation broth of Trichoderma sp. USF-2690 strain isolated from a soil sample. The structure of the compound was determined by elucidation of spectroscopic evidence. The compound was revealed to possess a new carbon skeleton in the group of oxidized sorbicillin dimers and was named bisorbibetanone. The stereostructure of bisorbibetanone was analyzed on the basis of the spectral data. In 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, bisorbibetanone gave an ED 30 value of 62.5 μM after standing for 30 min.