Keiichiro Ohnishi

Zinnimidine and 5-(3′,3′-dimethylallyloxy)-7-methoxy-6-methylphthalide from Alternaria porri

Abstract The structures of two metabolites, isolated from the culture liquid of Alternaria porri , have been identified as zinnimidine and 5-(3′,3′-dimethylallyloxy)-7-methoxy-6-methylphthalide. The latter is the first reported isolation as a naturally occurring product.

A Novel Isoindoline, Porritoxin Sulfonic Acid, from Alternaria porri and the Structure-phytotoxicity Correlation of Its Related Compounds

Novel zinniol-related compound 3, named porritoxin sulfonic acid, with an isoindoline skeleton was isolated from the culture liquid of Alternaria porri. The structure was determined to be 2-(2″-sulfoethyl)-4-methoxy-5-methyl-6-(3′-methyl-2′-butenyloxy)-2,3-dihydro-1H-isoindol-1-one. The phytotoxic activities of three isoindolines (1-3) were evaluated in a seedling-growth assay against stone leek and lettuce.

Structure of Porriolide, a New Metabolite from Alternaria porri

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Biosynthesis of macrosporin by Alternaria porri

Abstract The biosynthesis of macrosporin, a metabolise of Alternaria porri, was elucidated by incorporation experiments of single and double labelled acetates. 13C NMR assignments were also established.

Isolation and Identification of 6-(3′,3′-Dimethylallyloxy)-4-methoxy-5-methylphthalide from Alternaria porri

Isolation and Identification of 6-(3′,3′Dimethylallyloxy)-4-methoxy-5-methylphthalide from Alternaria porri Rikisaku Suemitsu, Keiichiro Ohnishi, Masayuki Horiuchi & Yoshiyuki Morikawa To cite this article: Rikisaku Suemitsu, Keiichiro Ohnishi, Masayuki Horiuchi & Yoshiyuki Morikawa (1992) Isolation and Identification of 6-(3′,3′-Dimethylallyloxy)-4-methoxy-5methylphthalide from Alternaria porri, Bioscience, Biotechnology, and Biochemistry, 56:6, 986-986, DOI: 10.1271/bbb.56.986 To link to this article: http://dx.doi.org/10.1271/bbb.56.986

Biosyntheses of alterporriol D and E by Alternaria porri

Abstract The biosyntheses of alterporriol D and E, metabolites of Alternaria porri were elucidated by incorporation experiments of single and double labelled acetates. 13 C NMR assignments were also established.

Porritoxins, metabolites of Alternaria porri, as anti-tumor-promoting active compounds

To search for possible cancer chemopreventive agents from natural sources, we performed primary screening of metabolites of Alternaria porri by examining their possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. The ethyl acetate extract of A. porri showed the inhibitory effect on EBV-EA activation. Three porritoxins (1–3) were obtained as inhibitory active compounds for EBV-EA from ethyl acetate extract. 6-(3′,3′-Dimethylallyloxy)-4-methoxy-5-methylphthalide (2) showed the strongest activity among them. Inhibitory effect of porritoxin (1) and (2) was superior to that of β-carotene, a well-known anti-tumor promoter. Furthermore, the structure–activity correlation of porritoxins and their related compounds were discussed.

High-performance liquid chromatographic determination of tentoxin in fermentation of Alternaria porri (Ellis) Ciferri

Abstract Tentoxin is an interesting non-specific toxin produced by some Alternaria species, known as pathogenic organisms. The high-performance liquid chromatographic determination of tentoxin by using a YMCA-312 column, a reversed type of octadecylsilica, with 0.05 M ammonium dihydrogenphosphate—acetonitrile (7:3) as the mobile phase is described. The limit of detection is 0.1 μg/ml. One assay can be performed by using culture liquid without any other procedures within 30 min.