Kaneo Kanoh

(−)-Phenylahistin: A new mammalian cell cycle inhibitor produced by aspergillus ustus

Abstract (−)-Phenylahistin is a fungal diketopiperazine metabolite consisting of L -phenylalanine and isoprenylated dehydrohistidine, and it showed an inhibitory activity on the cell cycle progression of P388 cells in the G2/M phase.

Mechercharmycins A and B, cytotoxic substances from marine-derived Thermoactinomyces sp. YM3-251.

A new cytotoxic substance named mechercharmycin A was isolated from marine-derived Thermoactinomyces sp. YM3-251. The structure of mechercharmycin A was determined by an X-ray crystallographic analysis to be cyclic peptide-like and bearing four oxazoles and a thiazole. Mechercharmycin B, a linear congener of mechercharmycin A, was also isolated from the same bacterium. Mechercharmycin A exhibited relatively strong antitumor activity, whereas mechercharmycin B exhibited almost no such activity.

Effect of Exogenous Siderophores on Iron Uptake Activity of Marine Bacteria under Iron-Limited Conditions

ABSTRACT More than 60% of species examined from a total of 421 strains of heterotrophic marine bacteria which were isolated from marine sponges and seawater were observed to have no detectable siderophore production even when Fe(III) was present in the culture medium at a concentration of 1.0 pM. The growth of one such non-siderophore-producing strain, alpha proteobacterium V0210, was stimulated under iron-limited conditions with the addition of an isolated exogenous siderophore,N,N′-bis (2,3-dihydroxybenzoyl)-O-serylserine from aVibrio sp. Growth was also stimulated by the addition of three exogenous siderophore extracts from siderophore-producing bacteria. Radioisotope studies using 59Fe showed that the iron uptake ability of V0210 increased only with the addition of exogenous siderophores. Biosynthesis of a hydroxamate siderophore by V0210 was shown by paper electrophoresis and chemical assays for the detection of hydroxamates and catechols. An 85-kDa iron-regulated outer membrane protein was induced only under iron-limited conditions in the presence of exogenous siderophores. This is the first report of bacterial iron uptake through an induced siderophore in response to exogenous siderophores. Our results suggest that siderophores are necessary signaling compounds for growth and for iron uptake by some non-siderophore-producing marine bacteria under iron-limited conditions.

Synthesis and biological activities of phenylahistin derivatives

X-ray crystallographic analysis was performed and several phenylahistin derivatives were synthesized to elucidate the structural components necessary for the anti-microtubule activity of phenylahistin. We primarily focused on the unique isoprenylated dehydrohistidine structure. Our results showed that a uniplanar pseudo-three-ring structure formed by the hydrogen bonding of diketopiperazine and imidazole rings is important for the anti-microtubule activity of phenylahistin.

Discovery of a Marine Bacterium Producing 4-Hydroxybenzoate and Its Alkyl Esters, Parabens

ABSTRACT Chemically synthesized 4-hydroxybenzoate (4HBA) is widely used in the chemical and electrical industries as a material for producing polymers such as those of the liquid crystal type. Its alkyl esters, called parabens, have been the most widely used preservatives by the food and cosmetic industries. We report here for the first time a microorganism, a marine bacterium, which biosynthesizes these petrochemical products. The marine bacterial strain, A4B-17, which was found to belong to the genus Microbulbifer on the basis of its rRNA and gyrB sequences, was isolated from an ascidian in the coastal waters of Palau. Strain A4B-17 was, surprisingly, found to produce 10 mg/liter of 4HBA, together with its butyl (24 mg/liter), heptyl (0.4 mg/liter), and nonyl (6 mg/liter) esters. We therefore characterized 23 other marine bacteria belonging to the genus Microbulbifer, which our institute had previously isolated from various marine environments, and found that these bacteria also produced 4HBA, although with low production levels (less than one-fifth of that produced by A4B-17). We also show that the alkyl esters of 4HBA produced by strain A4B-17 were effective in preventing the growth of yeasts, molds, and gram-positive bacteria.

Urukthapelstatin A, a novel cytotoxic substance from marine-derived Mechercharimyces asporophorigenens YM11-542. I. Fermentation, isolation and biological activities.

Urukthapelstatin A, a novel cyclic peptide, was isolated from the cultured mycelia of marine-derived Thermoactinomycetaceae bacterium Mechercharimyces asporophorigenens YM11-542. The peptide was purified by solvent extraction, silica gel chromatography, ODS flash chromatography, and finally by preparative HPLC. Urukthapelstatin A dose-dependently inhibited the growth of human lung cancer A549 cells with an IC50 value of 12 nM. Urukthapelstatin A also showed potent cytotoxic activity against a human cancer cell line panel.

Three New Polyketide−Terpenoid Hybrids from Penicillium sp.

Three novel hybrid polyketide-terpenoid metabolites were isolated from a Penicillium minioluteum strain. Their structures were determined by NMR spectroscopic analyses and X-ray crystallography. The proposed biosynthetic pathway including a unique retro-Claisen migration of methyl carbonate correlates the three compounds with berkeleydione and berkeleytrione.

Isolation of Marine Bacteria by In Situ Culture on Media-Supplemented Polyurethane Foam

Polyurethane foam (PUF) supplemented with various agar media was used in situ to trap marine bacteria and it consequently provided a substrate on which they could be cultivated while exposed to natural seawater in the coral reef area. The bacterial population on the PUF blocks was analyzed by denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR)-amplified 16S rDNA fragments. Changing the composition of the cultivation medium in the PUF blocks and selecting different sampling sites resulted in different bacteria being detected on the PUF blocks. For example, iron-utilizing (IU) bacteria, siderophore-producing (SP) bacteria, and petroleum-degrading (PD) bacteria were isolated from PUF blocks and it was discovered that IU and SP contained iron and PD contained hydrocarbon. This method opens up the possibility for isolating novel and useful marine bacteria.

New Sulfoalkylresorcinol from Marine-derived Fungus, Zygosporium sp. KNC52

A new sulfoalkylresorcinol (1) was isolated from the marine-derived fungus, Zygosporium sp. KNC52. The structure of 1 was elucidated by spectroscopic methods including MS and NMR, and the absolute stereochemistry was determined by the modified Moshers method. Compound 1 inhibited FtsZ polymerization in vitro and exhibited weak antimicrobial activity against multi-drugresistant bacteria.

Characterization of Sphingomonas aldehyde dehydrogenase catalyzing the conversion of various aromatic aldehydes to their carboxylic acids

An aldehyde dehydrogenase gene, designated phnN, was isolated from a genome library of the 1,4-dimethylnaphthalene-utilizing soil bacterium, Sphingomonas sp. 14DN61. Escherichia coli expressing the phnN gene converted 1,4-dihydroxymethylnaphthalene to 1-hydroxymethyl-4-naphthoic acid. The putative amino acid sequence of the phnN gene product had 31–42% identity with those of NAD+-dependent short-chain aliphatic aldehyde dehydrogenases and a secondary alcohol dehydrogenase. The NAD(P)+-binding site and two consensus sequences involved in the active site for aldehyde dehydrogenase are conserved among these proteins. The PhnN enzyme purified from recombinant E. coli showed broad substrate specificity towards various aromatic aldehydes, i.e., 1- and 2-naphaldehydes, cinnamaldehyde, vanillin, syringaldehyde, benzaldehyde and benzaldehydes substituted with a hydroxyl, methyl, methoxy, chloro, fluoro, or nitro group were converted to their corresponding carboxylic acids. Interestingly, E. coli expressing phnN was able to biotransform a variety of not only aromatic aldehydes, but also aromatic alcohols to carboxylic acids.