Shinsuke Fujihara

Occurrence of a new polyamine, canavalmine, in the sword bean Canavalia gladiata

Abstract A new tetraamine was detected in the seed of sword bean Canavalia gladiata and named canavalmine. The chemical structure was determined to be NH2 (CH2) 4NH(CH2) 3NH(CH2) 4NH2 (1,13-diamino-5,9-diazatridecane) based on gas chromatography-mass spectrometry after derivatization of polyamines with pentafluoropropionic anhydride. The proof of identity was established by comparison of infrared and 1H-NMR spectra of the tetraamine isolated from sword bean with those of a synthetic compound.

Isolation and identification of an allelopathic substance from peel of Citrus junos.

The inhibitory effect of Citrus junos peel on plant growth using lettuce (Lactuca sativa L.) as a bioassay material was investigated, since the powder of the peel had been found to inhibit growth of weeds. Basic, neutral and acidic fractions were separated from the aqueous fraction obtained from the methanol extract of C. junos peel. All fractions inhibited the growth of lettuce seedlings, but by far the greatest inhibition was observed with the neutral fraction. Thus, the latter was further purified and an allelopathically active substance was isolated. The structure of the substance was determined from high-resolution MS and 1H and 13C NMR spectral data as abscisic acid-beta-D-glucopyranosyl ester (ABA-GE). ABA-GE inhibited hypocotyl and root growth of lettuce seedlings at concentrations greater than 0.3 microM, and the concentrations for 50% inhibition of hypocotyl and root growth were 2.3 and 1.4 microM, respectively. The effectiveness of ABA-GE on inhibition of growth and the occurrence of ABA-GE in the peel itself suggested that ABA-GE may play an important role in the allelopathic potential of C. junos peel. The peel may be potentially useful for weed management in a field setting.

Probable site of allantoin formation in nodulating soybean plants

Abstract Nodulated soybean plants contain high concentration of allantoin in all parts. Excision of nodules from the roots brought about a marked decrease in allantoin. To examine the function of nodules in allantoin production, nodulated and nodule-detached soybeans were fed with 15NH3 for 1 week. High abundance of 15N was found in the amino acid-N fraction of both plants. In the root and stem of the nodulated plants, ca 80% of the nitrogen in this fraction was derived from the NH3 added in the medium. Excess 15N was detected also in allantoin-N fraction, but the 15N content was very low in contrast to that in amino acid-N fraction. The site involved in the allantoin formation and the possible significance of its synthesis are discussed in relation to symbiotic nitrogen fixation.

Fast-growing root nodule bacteria produce a novel polyamine, aminobutylhomospermidine

Polyamines in various root nodule bacteria including Bradyrhizobium japonicum, Rhizobium fredii, R. leguminosarum, R. meliloti and R. loti were identified by capillary gas chromatography. Homospermidine was the polyamine present in highest concentration in all the rhizobia tested. In addition to putrescine and homospermidine, fast-growing type of rhizobial cells contained a novel polyamine, aminobutylhomospermidine, NH2(CH2)4NH(CH2)4NH(CH2)4NH2. The unusual tetraamine was not found in the cells of slow-growing type of rhizobia throughout their growth period, indicating a difference in polyamine metabolism between fast-growing type and slow-growing type of root nodule bacteria.

Determination of 15NH3 by gas chromatography-mass spectrometry : Application to the measurement of putrescine oxidation by human plasma

A convenient and sensitive method for the determination of 15NH3 has been developed. Ammonia was purified from sample solutions by a modified microdiffusion method, derivatized with pentafluorobenzoyl chloride to pentafluorobenzamide (PFBA) and determined by gas chromatography-mass spectrometry using a multiple ion detector. PFBA was eluted from the gas chromatographic column within 2 min and resulted in a simple mass fragmentation pattern. The 15N/14N ratio was accurately determined with picomole amounts of PFBA by measuring the molecular ions of PFBA and [15N]PFBA. The method was applied to the assay of putrescine oxidation by human plasma. 15NH3 was produced by incubating 15N-labelled putrescine with plasma. The 15NH3 production was time dependent and strongly inhibited by the addition of aminoguanidine, an inhibitor of diamine oxidase. Exceedingly high 15NH3 production from [15N]putrescine was observed in the plasma from pregnant women. In contrast, only trace amounts of 15NH3 were formed in the plasma from normal men and non-pregnant women. The method seems to be applicable to various biological systems that produce ammonia as a metabolic product.

Determination of polyamines in human blood by electron-capture gas-liquid chromatography

The present work was undertaken to develop a sensitive and selective method for the estimation of putrescine, spermidine and spermine in human blood employing electron-capture gas--liquid chromatography. Polyamines were derivatized with heptafluorobutyric anhydride. The heptafluorobutyric derivatives of polyamines could be well resolved within 15 min under a temperature programme. The detection limit was 0.1 pmol for putrescine and cadaverine, and 0.02 pmol for spermidine and spermine. The method was applied to polyamine determinations in erythrocytes from human blood. For pre-separation of the polyamines from other compounds, a simple clean-up method utilizing an activated Permutit has been devised. Major interfering substances could be removed by the batchwise Permutit treatment. The mean values of spermidine and spermine concentrations, and the spermidine/spermine ratio in erythrocytes obtained from normal subjects (n = 11) were similar to reported values. The analytical procedure is thought to be applicable to various biological materials.

Formation of two major nicotine metabolites in livers of guinea pigs

Using antibody against NADPH-cytochrome P-450 reductase and several effectors of cytochrome P-450 and FAD-containing monooxygenase, we investigated nicotine metabolites formed by these two enzymes. When [3H]nicotine was metabolized by the combination of liver microsomes of guinea pigs and partially purified aldehyde oxidase, three distinct spots corresponding to nicotine, cotinine and nicotine-1-oxide were observed on fluorograms of thin-layer chromatography. Antibody against NADPH-cytochrome P-450 reductase inhibited the formation of cotinine but not nicotine-1-oxide. Metyrapone and n-octylamine inhibited the cotinine formation, while methimazole prevented the formation of nicotine-1-oxide. These results show that microsomal electron transport systems participate in the formation of nicotine-1-oxide and strongly suggest the involvement of FAD-containing monooxygenase in the formation of nicotine-1-oxide.

Effects of the spermine analogue canavalmine on proliferation of murine erythroleukemia cells in culture

The effects of canavalmine, a structural analogue of spermine, were studied in cultured murine erythroleukemia cells 745A. Canavalmine exerted an inhibition on murine erythroleukemia cell growth at concentrations over 50 microM. The cell proliferation was, however, restored when canavalmine was removed from the culture medium after 24 h. Treatment of the cells with 500 microM canavalmine blocked the accumulation of intracellular polyamines. Especially, both spermine and spermidine levels were reduced below 50% of those in control cells after 48 h and below 30% after 96 h. The decreased contents of spermine and spermidine were compensated for by the increased content of canavalmine incorporated within the cells. In these cells, RNA and protein contents also decreased. The degree of growth inhibition by canavalmine during the cell cycle was examined using synchronized cells. Serum-induced growth stimulation was inhibited by canavalmine most effectively in the cells at G1 phase prior to DNA synthesis. The antiproliferative effect decreased when canavalmine was added to the cells after commencement of DNA synthesis. The results suggest that the growth-inhibitory action of canavalmine on murine erythroleukemia cells is most likely due to an inhibition of early events of the cell cycle, possibly due to the interference of a structure-specific function of spermidine and/or spermine on DNA replication.

Erythroid differentiation of cultured murine erythroleukemia cells by the spermine analogue canavalmine

Canavalmine, an analogue of spermine, induced erythroid differentiation of murine erythroleukemia cells 745A, as evidenced by benzidine staining and heme content of cultured cells. Benzidine-positive cells synthesizing hemoglobin appeared on day 4 after addition of 250 microM canavalmine. The canavalmine-induced cell differentiation was inhibited by the addition of agents which alter the structure of the cell membrane, such as local anesthetics (procainamide and lidocaine) or Ca2+ antagonists (nifedipine and verapamil) at dosages not toxic for the cell growth. Canavalmine did not significantly affect the levels of conjugated polyamines in the acid-insoluble fraction of the cells. In contrast, the level of free spermidine in the acid-soluble fraction greatly decreased during the 18 h after canavalmine treatment. Putrescine and spermidine, when added externally to the growth medium, showed dose-dependent inhibition of canavalmine-induced cell differentiation. Neither cadaverine nor spermine had any significant effect. These results suggest that not only structural change of cell membrane but alteration of the polyamine metabolism, especially a regulation of the cellular level of free spermidine, might have a key importance in erythroid differentiation of murine erythroleukemia cells induced by canavalmine.