Akira Hirota's research while affiliated with University of Shizuoka and other places

Publications (108)

Article
Surugapyrone A, a novel 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging 2-pyrone, was isolated from the culture filtrate of an actinomycete strain USF-6280. This strain was assigned to the genus Streptomyces owing to its morphological and chemotaxonomic characteristics. Phylogenetic analysis based on 16S ribosomal RNA gene sequences support...
Article
Two 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging compounds were isolated from soybean miso. They were determined to be 2,4,4'-trihydroxydeoxybenzoin and 3'-hydroxydaidzein on the basis of spectroscopic data. In the manufacturing process for soybean miso, 2,4,4'-trihydroxydeoxybenzoin appeared during culture aging, and the quantity of it...
Article
Aspernolide A and butyrolactones I and II showed inhibitory activities against soybean lipoxygenase. All of them also had DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity. An analysis of the mechanism for radical scavenging allowed us to deduce that aspernolide A was converted to a quinone methide by a reaction with two molecules of...
Article
Six compounds were isolated as radical scavengers from the culture broth of a marine-derived actinomycete strain USF-TC31. The structures of two novel compounds were determined to be those of N-carbamoyl-2,3-dihydroxybenzamide (5) and 2-acetamido-3-(2,3-dihydroxybenzoylthio)propanoic acid (6), and four known compounds were identified to be anthrani...
Article
Two new indole derivatives (3, 4) and three known compounds (1, 2, 5) were isolated as radical scavengers from the culture filtrate of a marine sponge-derived yeast. Their structures were determined to be tyrosol (1), tryptophol (2), 2-(1H-indol-3-yl)ethyl 2-hydroxypropanoate (3), 2-(1H-indol-3-yl)ethyl 5-hydroxypentanoate (4), and cyclo(L-Pro-L-Ty...
Article
Two compounds were isolated from biotransformation of daidzein, a soybean isoflavone, by Aspergillus oryzae. One was 6,7,8,4'-tetrahydroxyisoflavone, an A-ring dihydroxylated daidzein, and the other was a novel compound which had the cleaved B-ring of daidzein. The former was perhaps derived from 8-hydroxydaidzein and/or 6-hydroxydaidzein, and had...
Article
In our searching program for novel sorbicillin related compounds, three novel compounds, spirosorbicillinols A (1), B (2), and C (3), were isolated from the fermentation broth of the USF-4860 strain isolated from a soil sample. The planar structures of compounds 1-3 were determined from spectroscopic evidence and degradation reaction, and that of 1...
Article
Two new N-hydroxypyrroles, surugapyrroles A and B, were isolated as DPPH radical-scavengers from a culture broth of Streptomyces sp. USF-6280 strain. The structures of the two compounds were elucidated by spectroscopic evidences and derivatization. Their DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity was as high as that of butylhy...
Article
We identified a new radical scavenger, ansaetherone (C26 H33 NO7), from a culture of the Streptomyces sp. USF-4727 strain. In our previous study, it was shown that this strain produced four lipoxygenase inhibitors, tetrapetalones A, B, C and D. The chemical structure of ansaetherone was elucidated by the spectroscopic method, indicating that this c...
Article
The biosynthesis of tetrapetalones (tetrapetalones A, B, C, and D) in Streptomyces sp. USF-4727 was studied by feeding experiments with [1-13C] sodium propanoate, [1-13C] sodium butanoate, [carbonyl-13C] 3-amino-5-hydroxybenzoic acid (AHBA) hydrochloride, and [1-13C] glucose, followed by analysis of the 13C-NMR spectra. These feeding experiments re...
Article
In our screening program for antioxidants with 1,1-diphenyl-2-picrylhydrazyl (DPPH)-radical scavenging activity, two novel compounds, demethylbisorbibutenolide (1) and trichopyrone (2), were isolated from the fermentation broth of the fungus of USF-4860 strain isolated from a soil sample. The structures of these compounds were determined from spect...
Article
Full-text available
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. Am...
Article
In the course of our screening to find 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavengers, we isolated eleven sorbicillin-related compounds, including seven novel compounds, from the fermentation broth of Trichoderma sp. USF-2690. The "bisorbicillinoids" was recently defined by Nicolaou as the term used to designate a group composed of dimeri...
Article
Full-text available
We isolated from soybean miso 8-hydroxyglycitein and 6-hydroxydaidzein as DPPH-radical scavengers, and elucidated their chemical structures by mass spectrometric, and (1)H- and (13)C-NMR spectrosopic analyses. These compounds showed DPPH-radical scavenging activity as high as that of alpha-tocopherol, 8-hydroxygenistein and 8-hydroxydaidzein. This...
Article
Three novel lipoxygenase inhibitors, tetrapetalone B (2, C(28)H(35)NO(9)), C (3, C(26)H(34)NO(8)), and D (4, C(28)H(36)NO(10)), 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...
Article
A simple new assay was designed for lipoxygenase inhibitors. This assay was used to find the novel lipoxygenase inhibitor, tetrapetalone A (1). Tetrapetalone A (1), C26H33NO7, was isolated from Streptomyces sp. USF-4727 strain. Its planar structure was determined by spectroscopic evidence and by methylating with diazomethane to show the presence of...
Article
Tetrapetalone A (I), C26H33O7N, 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 1H NMR, NOESY data and modified Mosher’s method....
Article
Full-text available
The antimutagenic activity of four isoflavones isolated from soybean miso toward three kinds of mutagens, AF-2, MNNG, and Trp-P-1, was evaluated by the Ames test. 8-Hydroxyisoflavones had greater suppressive potency than that of daidzein, and 6-hydroxydaidzein had almost the same activity as daidzein. These results indicated the number of hydroxy a...
Article
The antimutagenic activity of four isoflavones isolated from soybean miso toward three kinds of mutagens, AF-2, MNNG, and Trp-P-1, was evaluated by the Ames test. 8-Hydroxyisoflavones had greater suppressive potency than that of daidzein, and 6-hydroxydaidzein had almost the same activity as daidzein. These results indicated the number of hydroxy a...
Article
An incorporation study of [1-(13)C] and [1,2-(13)C2] labeled sodium acetates into sorbicillinol 1 established a ring closure system between C-1 and C-6 and the positions that were oxidized and/or methylated on a hexaketide chain. Subsequent investigations, using 13C-labeled 1 prepared from [1-(13)C] labeled sodium acetate, clearly demonstrated that...
Article
A potent antioxidant, bisorbicillinol, which is a member of the bisorbicillinoid family isolated from the culture broth of Trichoderma sp. USF-2690, produces a stable radical-terminated symmetric dimer by donating two hydrogen atoms to the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.
Article
Biosynthetic incorporation of labeled sodium acetate into oxosorbicillinol in Trichoderma sp. USF-2690 suggests that oxosorbicillinol is derived from six acetate units, and subsequent bioconversion of the labeled oxosorbicillinol to bisvertinolone in the fermentation of the strain suggests that bisvertinolone is biosynthesized from oxosorbicillinol...
Article
Full-text available
In the course of our screening program for free radical scavengers from Trichoderma sp. USF-2690, we found an unidentified metabolite (1) that appeared by the method used for HPLC analysis. Metabolite 1 gradually decreased with the production of bisorbicillinoids and was easily missed during the general isolation procedure. The LC-ESI-MS (negative)...
Article
Biosynthetic incorporation of labelled sodium acetates into bisorbicillinol in Trichoderma sp. USF-2690 suggests that bisorbicillinol is derived from 12 acetate units. Successful bioconversion of the labelled bisorbicillinols to bisorbibutenolides (bislongiquinolides) and bisorbicillinolides using the washed mycelium of the strain suggests tha...
Article
Guided by their DPPH radical-scavenging activity, nine compounds were isolated from soybean miso. Of these, 8-hydroxydaidzein, 8-hydroxygenistein and syringic acid had as high DPPH radical-scavenging activity as that of alpha-tocopherol. The antiproliferative activity of four of the isolated isoflavones toward three cancer cell lines was examined....
Article
Guided by their DPPH radical-scavenging activity, nine compounds were isolated from soybean mise. Of these, 8-hydroxydaidzein, 8-hydroxygenistein and syringic acid had as high DPPH radical-scavenging activity as that of alpha-tocopherol. The antiproliferative activity of four of the isolated isoflavones toward three cancer cell lines was examined....
Article
Full-text available
The novel compounds, demethylsorbicillin (1) and oxosorbicillinol (2), were isolated from a fermentation broth of Trichoderma sp. USF-2690. The structures of these compounds, which were determined from spectroscopic evidence, suggest the possibility that methylation at C-6 and oxidation at C-1 and C-6 of sorbicillin were controlled in the early pol...
Article
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 re...
Article
A novel indophenol-reducing and DPPH radical-scavenging compound (1) was isolated from a fungal metabolite. The structure of 1 was determined by a spectroscopic analysis, and the absolute configuration of 1 was determined by the modified Mosher's method. Compound 1 showed slow-reacting DPPH radical-scavenging activity (ED50 value of 298 μM after 96...
Article
A novel indophenol-reducing and DPPH radical-scavenging compound (1) was isolated from a fungal metabolite. The structure of 1 was determined by a spectroscopic analysis, and the absolute configuration of 1 was determined by the modified Mosher’s method. Compound 1 showed slow-reacting DPPH radical-scavenging activity (ED50 value of 298 μM after 96...
Article
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 sorbic...
Article
The indophenol-reducing compound, 4-hydroxy-3,6-dimethyl-2 H-pyrane-2-one (I), was isolated from the culture filtrate of an unidentified fungus. I also reacted with the DPPH radical to form a reaction product IV which was determined to be 1-[4-(3,4-dihydro-3,6-dimethyl-2,4-dioxo- 2 H-pyran-3-yl)phenyl]-1-phenyl-2-picrylhydrazine. This is the first...
Article
Full-text available
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 t...
Article
In the course of our screening for free radical scavengers, (1′E)-erythro-4-(3′,4′-dihydroxypentenyl)oxazole (1) (1′E,4′S)-4-(3′-oxo-4′-hydroxypentenyl)oxazole (2) and 6-penryl-α-pyrone (3) were isolated from an unidentified fungal metabolite. These compounds, especially novel oxazolyl compound 2, inhibited the bactericidal effect of the Fenton rea...
Article
Four indophenol-reducing compounds, USF-406A, B, C, and D, were isolated from a culture filtrate of the fungus, Mortierella sp. USF-406 strain by chemical screening. Their structures were elucidated by spectroscopic evidence and chemical degradation. Two were new phenol compounds, N-(4,6-dihydroxy-2,3,5-trimethylbenzoyl)-glycine and its methyl este...
Chapter
Human beings have eaten and drunk fermented foods and beverages for over 6000 years. Research on the food factors in such traditional fermented foods and other foods is reaching increasingly sophisticated levels. In particular, food factors with tertiary functions, which may prevent diseases, have been isolated from many fermented foods and beverag...
Article
Ansamycin antibiotics (1-4) were isolated from the cultured broth of Streptomyces sp. USF-319 strain as a result of our screening for free radical scavengers. They inhibited the bactericidal effect of the Fenton reagent toward Bacillus subtilis by their radical scavenging activity. Some of them also showed inhibitory activity against lipid peroxida...
Article
Nonenzymatic glycation of bovine serum albumin (BSA) was inhibited in vitro by some extracts of 34 kinds of spices. The methanol extract of thyme (Thymus vulgaris) had the most potent inhibitory activity among them. Chromatographic purification yielded four flavonoids, quercetin (1), eriodictyol (2), 5,6,4'-trihydroxy-7,8,3'-trimethoxyflavone (3),...
Article
USF-19A, a soybean lipoxygenase (SBL) and human 5-lipoxygenase (5-LO) inhibitor, was isolated from Streptomyces sp. USF-19 strain. Its chemical structure was determined by spectroscopic evidence to be a new member of the antimycin antibiotic family. The IC50 value of USF-19A against 5-LO was 28.0 microM.
Article
The presence of copper and carbohydrate was demonstrated in an acidic ascorbate oxidase purified from Acremonium sp. HI-25. The enzyme was inhibited by cyanide, azide, and sulfide. The reaction product from L-ascorbic acid was identified to be dehydro-L-ascorbic acid. This enzyme did not oxidize other electron donors than ascorbate derivatives. Sto...
Article
A new phytotoxin, FCRR (Fusarium crown and root rot)-Toxin was isolated from the culture filtrate of Fusarium oxysporum f. sp. radicis-lycopersici. The structure of FCRR-Toxin was established as I on the basis of spectroscopic evidence. The threshold concentration of induced leaf necrosis for “Momotaro” a susceptible cultivar of tomato (Lycopersico...
Article
In the course of our search for new indophenol-reducing substances, a strain of Streptomyces was found to produce USF-142A, a novel 1,3-dicarbonyl compound which reduces 2,6-dichlorophenol in-dophenol and exists in keto-enol tautomers in solution. This compound showed antioxidative activity by the Rhodan iron method.
Article
The glycosidation of (+)catechin, which has five hydroxyl groups with cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) and soluble starch has been studied. One of the transfer products was purified and its structure was determined to be (+)catechin 3ʹ-0-α-D-glucopyranoside. This glucoside noncompetitively inhibited the activity of tyrosinase f...
Article
Treatment of the epoxide 3 which is derived from a sesquiterpene antitumour antibiotic, terrecyclic acid A 1, with BF3·OEt2 in benzene, affords a skeletally rearranged ether 6 as the sole product; its structure was deduced from spectroscopic data including, 2D NMR data, to be [1S, 2S, 4R, 7R, 10S, 13R]-2-hydroxy-11,11-dimethyl-5-oxatetracyclo[5.5.1...
Article
Full-text available
A new chlorine-containing metabolite has been isolated from two fungi, and its structure including absolute stereochemistry was established by spectroscopic and X-ray crystallographic studies.
Article
Two kinds of hydride (sodium borohydride and diisobutylaluminium hydride) and catalytic hydrogenation have been used to reduce terrecyclic acid A 1 and several derivatives 5,6,7 and 15. Some interesting stereochemical results were obtained.
Article
The structure of a new antitumor antibiotic, myrocin C, from a strain of Myrothecium verrucaria was characterized as a pentacyclic pimarane diterpene composed of a gamma-lactol group and a unique cyclopropane ring on the basis of its physico-chemical properties and spectroscopic data as well as a single-crystal X-ray diffraction analysis of its mon...
Article
A new diterpene antitumor antibiotic, myrocin C, has been isolated from the culture filtrate of a soil fungus, Myrothecium verrucaria strain No. 55. The antibiotic was effective against Gram-positive bacteria, fungi and yeasts, and prolonged the life span of mice bearing Ehrlich ascites carcinoma.
Article
In the course of an investigation of the constituents of the fungus Sarcodon scabrosus (Phylacteriaceae), we found eight new types of bitter compounds named sarcodonin A∼H. This paper deals with the isolation and structural determination of these compounds from the titles fungus
Article
A novel antitumor antibiotic, methylenolactocin, was isolated from the culture filtrate of a new isolate of fungus identified as Penicillium sp. The fermentation yield reached about 100 mg per liter of the broth. Methylenolactocin has the molecular formula of C11H16O4 and possess an exomethylene lactone structure. Its structure was determined to be...
Article
Feeding experiments with [2-3H3]acetate and [2-13C2H3]acetate in Thom No. 14 indicated that the hydrogen at C-2 in terrecyclic acid A is incorporated without migration from the precursor acetic acid; the results favour our group's earlier speculation for the cyclization to the tricyclic skeleton in the biosynthetic scheme.
Article
The absolute configuration of cladospolide A, a phytotoxic macrolide produced by a fungus Cladosporium cladosporioides, was determined as (4R,5S,11R,2E)-4,5-dihydroxy-2-dodecen-11-olide by means of MTPA method.
Article
The structure of alahopcin (nourseimycin) (1), a new dipeptide antibiotic isolated from Streptomyces, has been established to be (2S, 3R)-2-[(L-alanyl)amino]-4-formyl-3-(hydroxy-aminocarbonyl)butyric acid. 1 exists in two cyclic hemiacetal type tautomers formed by intramolecular ring closure between the hydroxyamino group and the formyl group in aq...
Article
Two new plant growth regulators were isolated from a culture filtrate of Cladosporium cladosporioides. One of them is a root growth inhibitor of lettuce seedlings, cladospolide A, (E)-4, 5-dihydroxy-2-dodecen-11-olide and the other is a root growth promoter of lettuce seedlings, cladospolide B, (Z)-4, 5-dihydroxy-2-dodecen-11-olide. It is interesti...
Article
Assignment of the fifteen carbons of terrecyclic acid A, C15H20O3, a new sesquiterpene antibiotic, in the 13C NMR spectrum was performed by 13C-[1H] selective proton decoupling experiments, comparison with spectra of its derivatives and chemical shifts.