Papers by Hiroshi Ashihara
ACS Symposium Series, 2000
Page 1. Chapter 2 Pathways Involved in the Metabolism of Caffeine by Coffea and Camellia Plants G... more Page 1. Chapter 2 Pathways Involved in the Metabolism of Caffeine by Coffea and Camellia Plants George R. Waller1, Hiroshi Ashihara2, Misako Kato2, Thomas W. Baumann3, Alan Crozier4, and Takeo Suzuki5 1Department ...
Plant Science Letters, 1974
ABSTRACT
Phytochemistry, 1994
arabica; Rubiaceae; coffee; purine metabolism; purine alkaloid; adenine; caffeine: theobromine.
Zeitschrift Fur Naturforschung C, 2008
Using semi-quantitative reverse transcription-PCR, we studied the expression of genes encoding ca... more Using semi-quantitative reverse transcription-PCR, we studied the expression of genes encoding caffeine synthase (TCS1), inosine-5Ј-monophosphate dehydrogenase (TIDH), Sadenosyl-l-methionine synthase (sAMS), phenylalanine ammonia-lyase (PAL) and α-tubulin (Tua1) in young and mature leaves, stems and roots of 4-month-old tea seedlings and young and old tea tissue cultures. The amounts of transcripts of TCS1 were much higher in young leaves than in other parts of the plant. Expression of TIDH was greater in leaves than in other parts. Little difference in the amounts of transcripts of PAL, sAMS and Tua1 was found between various organs of tea seedlings. Larger amounts of transcripts of TCS1 and PAL were found in young callus tissues than in old tissues. These results support our conclusion deriving from previous enzymatic and metabolic studies that caffeine is synthesized mainly in young leaf tissues. We propose that marked caffeine biosynthesis in young leaves is dependent on a greater expression of the TCS1 gene in the organ.
Natural Product Communications, Jun 1, 2014
As part of our studies of the occurrence, biosynthesis, function and human use of trigonelline, w... more As part of our studies of the occurrence, biosynthesis, function and human use of trigonelline, we looked at trigonelline-accumulating plant species and at the distribution of trigonelline in different organs of trigonelline-accumulating non-leguminous plants. There are many trigonelline-synthesizing plant species, but apart from legume seeds only a few species accumulate high concentrations of trigonelline. We have found only three species that accumulate high levels of trigonelline: Murraya paniculata (orange jessamine), Coffea arabica (coffee) and Mirabilisjalapa (four o'clock flower). Trigonelline was found in all parts of Murraya paniculata seedlings at 4-13 micromol/g fresh weight; more than 70% was distributed in the leaves. In the coffee plant, trigonelline was found in all organs, and the concentrations in the upper stems, including tips (48 micromol/g FW) and seeds (26 micromol/g FW), were higher than in other organs. In Mirabilis jalapa plants, trigonelline was found in leaves, stems, flowers, roots and seeds; the concentration varied from 0.3 to 13 micromol/g FW and was generally higher in young tissues than in mature tissues, except for seeds. Exogenously supplied nicotinamide increases the trigonelline content. The in planta role of trigonelline and the possible use oftrigonelline-accumulating plants in herbal medicine are discussed.
Gan to Kagaku Ryoho Cancer Chemotherapy, Nov 1, 2003
Description/Abstract The Uptake and metabolism of sugars by suspension-cultured Catharanthus rose... more Description/Abstract The Uptake and metabolism of sugars by suspension-cultured Catharanthus roseus cells were investigated. Substantially all the sucrose in the culture medium was hydrolyzed to glucose and fructose before being taken up by the cells. The ...
Plant and Cell Physiology, 1997
Purine alkaloid catabolism pathways in young, mature and aged leaves of tea (Camellia sinensis L.... more Purine alkaloid catabolism pathways in young, mature and aged leaves of tea (Camellia sinensis L.) were investigated by incubating leaf sections with l4 C-labelled theobromine, caffeine, theophylline and xanthine. Incorporation of label into CO 2 was determined and methanolsoluble metabolites were analysed by high-performance liquid chromatography-radiocounting and thin layer chromatography. The data obtained demonstrate that theobromine is the immediate precursor of caffeine, which accumulates in tea leaves because its conversion to theophylline is the rate limiting step in the purine alkaloid catabolism pathway. The main fate of [8-14 C]theophylline incubated with mature and aged leaves, and to a lesser extent young leaves, is conversion to 3-methylxanthine and onto xanthine which is degraded to 14 CO 2 via the purine catabolism pathway. However, with young leaves, sizable amounts of [8-14 C]theophylline were salvaged for the synthesis of caffeine via a 3-methylxanthine -»• theobromine -* caffeine pathway. Trace amounts of [2-14 C]xanthine were also salvaged for caffeine biosynthesis in young leaves, by conversion to 3methylxanthine, and this was enhanced in the presence of 5 mM allopurinol which inhibits purine catabolism. Feeds of [2-14 C]xanthine to young leaves also indicated that 3methylxanthine, as well as being salvaged for theobromine and caffeine production, is also converted, via TV-l-methylation, to theophylline.
Journal of Gastroenterology, 2010
Purpose The aim of this study was to investigate the antitumor efficacy of treatment, identify pr... more Purpose The aim of this study was to investigate the antitumor efficacy of treatment, identify prognostic factors, and construct a prognostic index in patients with hepatocellular carcinoma treated by transcatheter arterial infusion chemotherapy (TAI) using cisplatin suspended in lipiodol. Methods We analyzed the outcomes in a total of 94 consecutive patients with previously untreated hepatocellular carcinoma who were treated by TAI using cisplatin suspended in lipiodol. Results Twenty-seven patients (29%) showed complete response and 21 patients (22%) showed partial response, with an overall response rate of 51% (95% confidence interval, 41-61%). The median survival time was 2.5 years and the proportions of survivors at 1, 2, and 5 years were 81.6, 65.2, and 18.3%, respectively. The results of multivariate analysis indicated a significant association of serum albumin C3.0 g/dL, maximum tumor size B3.0 cm, absence of ascites, and unilateral distribution of the tumors with a favorable survival. For clinical application, we also propose a prognostic index based on a combination of these prognostic factors. Based on this index, the patients were classified into three groups: those with good, intermediate, and poor prognosis. The median survival times in these three groups were 4.3, 2.7, and 1.1 years, respectively (p \ 0.01).
Plant and Cell Physiology, Sep 1, 2008
Planta, 2011
Cellular brassinolide (BL) levels regulate the development of Brassica napus microspore-derived e... more Cellular brassinolide (BL) levels regulate the development of Brassica napus microspore-derived embryos (MDEs). Synthesis and degradation of nucleotides were measured on developing MDEs treated with BL or brassinazole (BrZ), a biosynthetic inhibitor of BL. Purine metabolism was investigated by following the metabolic fate of 14 C-labelled adenine and adenosine, substrates of the salvage pathway, and inosine, an intermediate of both salvage and degradation pathways. For pyrimidine, orotic acid, uridine and uracil were employed as markers for the de novo (orotic acid), salvage (uridine and uracil), and degradation (uracil) pathways. Our results indicate that utilization of adenine, adenosine, and uridine for nucleotides and nucleic acids increased signiWcantly in BL-treated embryos at day 15 and remained high throughout the culture period. These metabolic changes were ascribed to the activities of the respective salvage enzymes: adenine phosphoribosyltransferase (EC 2.4.2.7), adenosine kinase (EC 2.7.1.20), and uridine kinase (EC 2.7.1.48), which were induced by BL applications. The BL promotion of salvage synthesis was accompanied by a reduction in the activities of the degradation pathways, suggesting the presence of competitive anabolic and catabolic mechanisms utilizing the labelled precursors. In BrZ-treated embryos, with depleted BL levels, the salvage activity of both purine and pyrimidine nucleotides was reduced and this was associated to structural abnormalities and poor embryonic performance. In these embryos, the activities of major salvage enzymes were consistently lower to those measured in their control (untreated) counterparts.
Zeitschrift für Pflanzenphysiologie, 1981
ABSTRACT
Zeitschrift für Naturforschung. C, Journal of biosciences
Leucaena leucocephala is a nitrogen-fixing tropical leguminous tree that produces two pyridine al... more Leucaena leucocephala is a nitrogen-fixing tropical leguminous tree that produces two pyridine alkaloids, i. e. mimosine [beta-(3-hydroxy-4-pyridon-1-yl)-L-alanine] and trigonelline (1-methylpyridinium-3-carboxylate). Mimosine has been detected in leaves, flowers, pods, seeds, and roots, and it is one of the principal non-protein amino acids that occurs in all organs. Asparagine was the most abundant amino acid in flowers. The mimosine content varied from 3.3 micromol/g fresh weight (FW) in developing flowers to 171 micromol/g FW in mature seeds. Trigonelline was also detected in leaves, flowers, pods, and seeds, but not roots. The trigonelline content was lower than that of mimosine in all organs. It varied from 0.12 micromol/g FW in developing seeds to 2.6 micromol/g FW in mature seeds. [2-14C]Nicotinic acid supplied to the developing seeds was incorporated into trigonelline but not mimosine. This indicates that the pyridine and dihydroxypyridine structures of these two alkaloids ...
International Journal of Biochemistry, 1983
ABSTRACT
Zeitschrift für Pflanzenphysiologie, 1974
ABSTRACT
Zeitschrift für Pflanzenphysiologie, 1981
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Papers by Hiroshi Ashihara