Yukio Ishiguro

Erinacines A, B, and C, strong stimulators of nerve growth factor (NGF)-synthesis, from the mycelia of Hericium erinaceum

Abstract The structures of novel diterpenoids, erinacines A, B, and C, isolated from the cultured mycelia of Hericium erinaceum were determined by interpretation of the spectral data, and chemical and enzymatic reactions. These compounds showed potent stimulating activity of nerve growth factor (NGF)-synthesis.

Hericenones C, D and E, stimulators of nerve growth factor (NGF)-synthesis, from the mushroom Hericium erinaceum.

Abstract Novel compounds, hericenones C ( 3 ), D ( 4 ) and ( 5 ) were isolated from the mushroom Hericium erinaceum . These structures were determined by interpretation of the spectral data, and chemical and enzymatic reactions. These compounds have stimulating activity of the synthesis of nerve growth factor (NGF).

Chromans, hericenones F, G and H from the mushroom Hericium erinaceum

Novel chromans, hericenones F, G and H were isolated from the mushroom Hericium erinaceum. These compounds stimulated the synthesis of nerve growth factor (NGF) in vitro.

Prevention of N-Methylnitrosourea-induced Colon Carcinogenesis in F344 Rats by Lycopene and Tomato Juice Rich in Lycopene

Epidemiological studies have suggested a protective effect of lycopene and lycopene‐rich tomatoes against various cancers. Here, the inhibition of colon carcinogenesis by lycopene and tomato juice was investigated. Seven‐week‐old female F344/NSlc rats received an intrarectal dose of 2 mg (experiment I) or 4 mg (experiment II) of N‐methylnitrosourea 3 times a week for 3 weeks, and had free access to one of 4 drinking fluids: plain water (control group), 17 ppm lycopene water solution (Ly group), and diluted tomato juice containing 17 ppm (Tj group) or 3.4 ppm (tj group) lycopene, throughout the experiments. The colon cancer incidence at week 35 was significantly lower in the Tj group, but not in the Ly group, than in the control group: 21% and 33% vs. 54%, in experiment I (24 rats in each group). It was significantly lower in the Tj group than in the tj and control groups, 40% vs. 72% and 84%, in experiment II (25 rats in each group). An appreciable amount of lycopene (0.02 μ/g) was detected in the colon mucosa of rats in the Tj group, but not in the tj group. The results suggest that tomato juice rich in lycopene may have a protective effect against colon carcinogenesis.

Consumption of carotenoids in photosensitized oxidation of human plasma and plasma low-density lipoprotein

Human plasma and plasma low-density lipoprotein (LDL) were exposed to photoirradiation in the presence of methylene blue (water-soluble photosensitizer) or 12-(1-pyrene)dodecanoic acid (P-12, lipid-soluble photosensitizer). In methylene-blue-sensitized photooxidation of human plasma and LDL, endogenous carotenoids and tocopherols were consumed with the accumulation of cholesteryl ester hydroperoxides (CE-OOH). Xanthophylls (zeaxanthin and lutein) decreased faster than lycopene and carotenes in the case of human plasma. In P-12-sensitized photooxidation of human plasma and LDL, the decrease rate of xanthophylls was slower than that of lycopene and carotenes. A lower level of beta-carotene exerted the effective inhibition of lipid peroxidation and retarded the oxidative loss of alpha-tocopherol, when the phosphatidylcholine liposomes containing these two lipid-soluble antioxidants were subjected to methylene blue- or P-12-sensitized photooxidation. These results suggest that antioxidant activity of carotenoids in photosensitized oxidation (Type II) of human plasma LDL depends on the site of singlet oxygen (1O2) to be generated and that carotenoids can protect tocopherols from the oxidative loss by 1O2 in the plasma.

Antimicrobial chlorinated orcinol derivatives from mycelia of Hericium erinaceum

Abstract Two novel and a known chlorinated orcinol derivative were isolated from cultured mycelia of Hericium erinaceum . These three compounds exhibited antimicrobial activities.

Dictyophorines A and B, two stimulators of NGF-synthesis from the mushroom Dictyophora indusiata

Two novel eudesmane-type sesquiterpenes, dictyophorines A and B, and a known compound, teucrenone, were isolated from the mushroom Dictyophora indusiata. Dictyophorines A and B promoted nerve growth factor (NGF)-synthesis by astroglial cells.

Reduction of Allergenic Proteins by the Effect of the ripening inhibitor (rin) Mutant Gene in an F1 Hybrid of the rin Mutant Tomato

The ripening inhibitor (rin) mutant tomato yields non-ripening fruit, and the rin hybrid fruit (RIN/rin) shows an intermediate phenotype between the wild and mutant fruit, that is, red-ripe and extended shelf life. We found by a microarray analysis that the genes encoding possible allergenic proteins were expressed at a significantly lower level in the rin hybrid fruit than in the wild-type fruit. These allergenic proteins, which were β-fructofuranosidase and polygalacturonase 2A (PG-2A), were confirmed to accumulate at a lower level in the rin hybrid fruit than in the wild-type fruit. The immunoglobulin E (IgE) in serum from a tomato-allergic patient showed lower reactivity to the extract of the rin hybrid fruit than to that of the wild fruit. These results suggest that the rin gene has the potential to regulate allergen accumulation in tomato fruit.

A pyradine-derivative from the mushroom Albatrellus confluens

A novel pyradine-derivative was isolated from the mushroom Albatrellus confluens. This compound promoted melanin synthesis by B16 melanoma cells.

Selective inhibitors of germination of legume seeds in activated sludge compost

Water extracts of the compost produced from activated sludge and coffee residue were found to be selectively inhibitory to seed germination of some legumes. Germination rate of white clover (Trifolium repens L.), red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) seeds were reduced to 2, 29 and 73% of the control, respectively, by water extracts of the compost (20 g l−1). However, the extracts did not show any inhibition to seed germination of sorghum (Sorghum bicolor Moench), African millet (Eleusine coracana Gaertn.), and Komatsuna (Brassica rapa L.) at the same concentration. The inhibitors in the compost extracts were separated by ion-exchange chromatography and reverse-phase high performance liquid chromatography (HPLC) and the inhibitory activities of seed germination were tested with white clover seeds. Five inhibitors were isolated and identified as 3,4-dichlorophenylacetic acid (3,4-DCP), 3,4-dichlorobenzoic acid (3,4-DCB), 3,4,5-trichlorophenylacetic acid, 3,4,5-trichlorobenzoic acid and mono-2-ethylhexylphthalate by 1H-, 13C-NMR spectroscopy and mass spectrometry. The inhibitory activities of some authentic chemicals of the inhibitors and the related compounds were compared. The results indicated that the main inhibitor in the compost could be 3,4-DCB, which was contained at the concentration of 6.58 mg kg−1 compost and showed the strongest inhibitory effect on seed germination of white clover among the tested compounds.