The Experts below are selected from a list of 930 Experts worldwide ranked by ideXlab platform
Hiroshi Ashihara - One of the best experts on this subject based on the ideXlab platform.
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Short Communication Biosynthesis of Purine Alkaloids in Camellia Plants
2016Co-Authors: Hiroshi Ashihara, Hiromi KubotaAbstract:The metabolism of [8-'*C]adenine and [8-14C]hypoxanthine in four species of Camellia plants was investigated in relation to the synthesis of Purine Alkaloids, caffeine and theobromine. Young leaves of C. sinensis had the ability to synthesize caffeine, but in C. inawadiensis, these labelled precursors were incorporated into theobromine, not caffeine. No synthesis of Purine Alkaloids could be detected in C. japonica and C. sasanqua leaves. Conventional "salvage " and degradation pathways of Purines were present in all species of Camellia plants examined. Key words: Adenine — Caffeine — Camellia plants — Purine Alkaloid — Purine salvage — Theobromine. Accumulation of Purine Alkaloids in plants of the genus Camellia has been found only in the species of the section Thea and in one strain of C. kissi of the section Paracamellia (Nagata and Sakai 1985, Nagata 1986). The major Purine Alkaloid found in C. sinensis and C. taliensis, of the section Thea, is caffeine (1,3,7-trimethylxanthine), but the major Purine Alkaloids found in C. irrawadiensis, of the same section, is theobromine (3,7-dimethylxanthine), with little or no caffeine being present (Nagata and Sakai 1985). In C. japonica and C. sasanqua, no purin
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Effect of Purine Alkaloids on the proliferation of lettuce cells derived from protoplasts.
Natural product communications, 2015Co-Authors: Hamako Sasamoto, Yoshiharu Fujii, Hiroshi AshiharaAbstract:To investigate the ecological role of caffeine, theobromine, theophylline and paraxanthine, which are released from Purine Alkaloid forming plants, the effects of these Purine Alkaloids on the divi...
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Metabolism of Purine Alkaloids and Xanthine in Leaves of maté (Ilex Paraguariensis)
Natural product communications, 2015Co-Authors: Yuling Yin, Riko Katahira, Hiroshi AshiharaAbstract:Accumulation and metabolism of Purine Alkaloids in leaves of mate (Ilex paraguariensis) were investigated. In winter, leaves accumulated caffeine but not theobromine, indicating that caffeine is the end product of Purine Alkaloid synthesis in mate. To elucidate the Purine Alkaloid metabolism in mate leaves, the metabolic fate of [8-(14)C]theobromine, [8-(14)C]theophylline, [8-(14)C]caffeine and [8-(14)C] xanthine was investigated in the leaf disks of young and mature leaves. In young mate leaves, significant amounts of theobromine and theophylline were utilized for caffeine biosynthesis, but the conversion was not observed in mature leaves. A small amount of theophylline was converted to theobromine. Practically no caffeine catabolism was detected in mate leaves during a 24 h-incubation. Catabolism of theobromine and theophylline via 3-methylxanthine was observed mainly in mature leaves. Xanthine was catabolised extensively via ureides in both young and mature leaves, but limited amounts are also utilized for the synthesis of theobromine, theophylline and caffeine. Possible pathways for the metabolism of Purine Alkaloids in mate leaves are discussed.
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Caffeine biosynthesis and adenine metabolism in transgenic Coffea canephora plants with reduced expression of N-methyltransferase genes.
Phytochemistry, 2006Co-Authors: Hiroshi Ashihara, Xin-qiang Zheng, Riko Katahira, Masayuki Morimoto, Shinjiro Ogita, Hiroshi SanoAbstract:In anti-sense and RNA interference transgenic plants of Coffea canephora in which the expression of CaMXMT1 was suppressed, caffeine biosynthesis from [8-(14)C]adenine was investigated, together with the overall metabolism of [8-(14)C]adenine. Compared with wild type control plants, total Purine Alkaloid biosynthesis from adenine and conversion of theobromine to caffeine were both reduced in the transgenic plants. As found previously, [8-(14)C]adenine was metabolised to salvage products (nucleotides and RNA), to degradation products (ureides and CO(2)) and to Purine Alkaloids (theobromine and caffeine). In the transgenic plants, metabolism of [8-(14)C]adenine shifted from Purine Alkaloid synthesis to Purine catabolism or salvage for nucleotides. HPLC analysis revealed a significantly reduced caffeine content in the transgenic plants. A small quantity (less than 20 nmol g(-1) fresh weight) of xanthosine had accumulated in at least one of the transgenic plants.
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Substrate specificity of N-methyltransferase involved in Purine Alkaloids synthesis is dependent upon one amino acid residue of the enzyme
Molecular genetics and genomics : MGG, 2005Co-Authors: Naho Yoneyama, Kouichi Mizuno, Hiroshi Ashihara, Hanayo Morimoto, Misako KatoAbstract:Caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine) are the major Purine Alkaloids in plants. To investigate the diversity of N-methyltransferases involved in Purine Alkaloid biosynthesis, we isolated the genes homologous for caffeine synthase from theobromine-accumulating plants. The predicted amino acid sequences of N-methyltransferases in theobromine-accumulating species in Camellia were more than 80% identical to caffeine synthase in C. sinensis. However, there was a little homology among the N-methyltransferases between Camellia and Theobroma. The recombinant enzymes derived from theobromine-accumulating plants had only 3-N-methyltransferase activity. The accumulation of Purine Alkaloids was, therefore, dependent on the substrate specificity of N-methyltransferase determined by one amino acid residue in the central part of the protein.
Liang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Change in tea polyphenol and Purine Alkaloid composition during solid-state fungal fermentation of postfermented tea.
Journal of agricultural and food chemistry, 2012Co-Authors: Jin-hua Qin, Liang ZhangAbstract:The aim of this study was to evaluate tea polyphenol and Purine Alkaloid contents of pu-erh tea (Camellia assamica) in a fermentation solid system with Aspergillus niger and Aspergillus fumigatu. In addition, the objective was to find the major intermediate product during fermentation by HPLC–MSn analysis. The results showed the change of catechin, ester-catechins and gallic acid by quantitative analysis. In the early stages, the contents of ester-catechins were lightly increased. Then, ester-catechins were gradually degraded to produce catechins and gallic acid. Furthermore, a major metabolic intermediate compound of catechins was observed and elucidated by HPLC–DAD–MSn analysis. This study provided a reliable dynamic data description and metabolic pathway of tea polyphenols for postfermented pu-erh tea.
Hiroshi Kurihara - One of the best experts on this subject based on the ideXlab platform.
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A comparative analysis of chemical compositions in Camellia sinensis var. puanensis Kurihara, a novel Chinese tea, by HPLC and UFLC-Q-TOF-MS/MS.
Food chemistry, 2016Co-Authors: Shu-hua Ouyang, Ting-mei Wang, Yi-qun Chang, Hai-yan Tian, Hong Cao, Hiroshi KuriharaAbstract:Camellia sinensis var. puanensis Kurihara (Puan tea) is a kind of ancient tea plant newly found in Jiangxipo and the surrounding areas of Puan County (Guizhou, China). People there always believe that drinking Puan tea is beneficial to the promotion of health and prevention of diseases. However, detailed information on its compositions has not been reported. Therefore, in this study, the varieties and contents of Purine Alkaloids and polyphenols in Puan tea were identified and determined by HPLC and UFLC-Q-TOF-MS/MS. Our results showed that theacrine, but not caffeine, was the dominated Purine Alkaloid detected in Puan tea. Meanwhile, Puan tea contained B-type procyanidin dimer, trimer and dimer monogallate, which were not detected in Camellia sinensis, Camellia ptilophylla and Camellia assamica var. kucha. The obtained results could support the local uses of Puan tea in health and nutrition and contribute to the research of tea variety.
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Theacrine, a Purine Alkaloid derived from Camellia assamica var. kucha, ameliorates impairments in learning and memory caused by restraint-induced central fatigue
Journal of Functional Foods, 2015Co-Authors: Min Chen, Chen Wang, Shu-hua Ouyang, Zhong-fu Mao, Bun Tsoi, Hiroshi KuriharaAbstract:Abstract Camellia assamica var. kucha is a local tea in the Yunnan province of China and people there believe its intake can relieve fatigue and their tiredness. Theacrine, a lesser-known Purine Alkaloid, was first discovered in this kind of tea. Here, we found that theacrine (15 mg/kg) could be absorbed into the blood and pass across the blood–brain barrier after oral administration. The effect and mechanism of theacrine on central fatigue were examined by employing a restraint stress model in mice. Results of behavioral tests suggested that oral administration of theacrine (5, 10, 15 mg/kg) significantly reversed learning and memory impairment caused by central fatigue. In addition, levels of fatigue-related neurotransmitters in the brains of restraint mice, including 5-hydroxytryptamine and dopamine as well as their metabolites, were restored by theacrine. Further, we found that the anti-fatigue effect of theacrine was associated with the regulation of brain glucose metabolism and the inhibition of phosphodiesterases.
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Theacrine, a Purine Alkaloid obtained from Camellia assamica var. kucha, attenuates restraint stress-provoked liver damage in mice.
Journal of agricultural and food chemistry, 2013Co-Authors: Yu-jia Zhai, Wei-min Chen, Hiroshi KuriharaAbstract:Theacrine (1,3,7,9-tetramethyluric acid), a Purine Alkaloid, has proven to be beneficial in maintaining several brain functions and is being studied for potential medicinal uses in recent years. In this study, we isolated theacrine from Camellia assamica var. kucha and investigated its protective effects on liver damage induced by restraint stress in mice. Results showed that 18 h of restraint stress could induce liver damage, with an obvious increase in levels of plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST). This finding was further confirmed by hepatic pathological examination, which showed inflammatory cell infiltration and focal necrosis of hepatocytes. However, oral administration of theacrine (10, 20, 30 mg/kg for 7 consecutive days) was found to decrease plasma ALT and AST levels, reduce hepatic mRNA levels of inflammatory mediators (IL-1β, TNF-α, IL-6, and IFN-γ), and reverse the histologic damages in stressed mice. Simultaneously, theacrine also significantly decreas...
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Theacrine, a special Purine Alkaloid with sedative and hypnotic properties from Cammelia assamica var. kucha in mice.
Journal of Asian Natural Products Research, 2007Co-Authors: Hiroshi Kurihara, Liang Zhao, Xin-sheng YaoAbstract:The central nervous system activities of theacrine (1,3,7,9-tetramethyluric acid), a Purine Alkaloid which is abundantly present in Camellia assamica var. kucha, were investigated in ambulatory activity, pentobarbital-induced sleep and forced swimming test in mice, compared with two other Purine Alkaloids, caffeine and theobromine. Caffeine treatment led to a marked increase in the ambulatory activity accompanied with decreasing of the immobility time in forced swimming test at both 10 and 30 mg/kg. Under the same conditions, neither theacrine nor theobromine showed obvious excited efficacy. Both doses of theacrine could significantly prolong the sleeping time induced by pentobarbital, while caffeine and theobromine exhibited an inverted effect. These results indicated that theacrine possessed potent sedative and hypnotic properties and its central nervous system effects were different from those of caffeine and theobromine.
Paulo Mazzafera - One of the best experts on this subject based on the ideXlab platform.
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Molecular and biochemical characterization of caffeine synthase and Purine Alkaloid concentration in guarana fruit
Phytochemistry, 2014Co-Authors: Flávia Camila Schimpl, Eduardo Kiyota, Juliana Lischka Sampaio Mayer, José Francisco De Carvalho Gonçalves, José Ferreira Da Silva, Paulo MazzaferaAbstract:Guarana seeds have the highest caffeine concentration among plants accumulating Purine Alkaloids, but in contrast with coffee and tea, practically nothing is known about caffeine metabolism in this Amazonian plant. In this study, the levels of Purine Alkaloids in tissues of five guarana cultivars were determined. Theobromine was the main Alkaloid that accumulated in leaves, stems, inflorescences and pericarps of fruit, while caffeine accumulated in the seeds and reached levels from 3.3% to 5.8%. In all tissues analysed, the Alkaloid concentration, whether theobromine or caffeine, was higher in young/immature tissues, then decreasing with plant development/maturation. Caffeine synthase activity was highest in seeds of immature fruit. A nucleotide sequence (PcCS) was assembled with sequences retrieved from the EST database REALGENE using sequences of caffeine synthase from coffee and tea, whose expression was also highest in seeds from immature fruit. The PcCS has 1083bp and the protein sequence has greater similarity and identity with the caffeine synthase from cocoa (BTS1) and tea (TCS1). A recombinant PcCS allowed functional characterization of the enzyme as a bifunctional CS, able to catalyse the methylation of 7-methylxanthine to theobromine (3,7-dimethylxanthine), and theobromine to caffeine (1,3,7-trimethylxanthine), respectively. Among several substrates tested, PcCS showed higher affinity for theobromine, differing from all other caffeine synthases described so far, which have higher affinity for paraxanthine. When compared to previous knowledge on the protein structure of coffee caffeine synthase, the unique substrate affinity of PcCS is probably explained by the amino acid residues found in the active site of the predicted protein.
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Decaf and the Steeplechase Towards Decaffito—the Coffee from Caffeine-Free Arabica Plants
Tropical Plant Biology, 2009Co-Authors: Paulo Mazzafera, Thomas W. Baumann, Milton Massao Shimizu, Maria Bernadete SilvarollaAbstract:Unquestionably, the popularity of the coffee beverage relies on its alerting attribute caffeine. However, susceptibilities to this Purine Alkaloid, quite frequently associated with health concerns, encouraged a significant market for decaffeinated coffee. The beans of Coffea arabica render the best beverage and a decaffeinated coffee has to preserve the desired organoleptic characteristics of this species. Consequently, besides technical removal of caffeine, the endeavors to attain a decaffeinated Arabica coffee range from traditional studies on genetic variability to advanced techniques to produce genetic modified coffee. The aim of this review is to recover part of this subject focusing mainly on the natural genetic variation for caffeine content in Arabica. We also present historical information about caffeine discovery and briefly discuss molecular approaches to reduce caffeine. We introduce here the term decaffito for coffee derived from Arabica plants with beans naturally low in or almost devoid of caffeine. In the near future, coffee drinkers avoiding caffeine will have the choice between basically three Arabica coffees, namely decaffeinated by (a) selection and breeding, (b) genetic modification and (c) industrial extraction. Although only the last decaf coffee is available for the consumers, we believe that the size of the market of each type will occupy in the future depend on the price and health aspects related to the way the decaffeinated coffee beans are obtained.
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Extraction of Purine Alkaloids from Maté (Ilex paraguariensis) Using Supercritical CO2
Journal of agricultural and food chemistry, 1999Co-Authors: Marleny D.a. Saldaña, Rahoma S. Mohamed, Martin G. Baer, Paulo MazzaferaAbstract:Experimental data for the supercritical CO2 extraction of Purine Alkaloids (caffeine, theobromine, and theophylline) from ground herbal mate tea (Ilex paraguaryensis) using a high-pressure apparatus are presented. Caffeine, theophylline, and theobromine were identified in the extracted fractions using HPLC. Results indicated a much higher CO2 selectivity for caffeine in comparison with those for theophylline and theobromine. Solubilities of pure compounds in carbon dioxide were also determined at 313.2, 323.2, 338.2, and 343.2 K, and pressures ranging from 14 to 24 MPa. Caffeine solubility exhibited a retrograde behavior with temperature while theophylline and theobromine manifested a normal behavior at conditions explored in this study. Solubilities in binary CO2/Purine Alkaloid model systems were much higher than those obtained during extraction of mate tea, demonstrating the difficulty of using binary data in predicting complex multicomponent behavior. Keywords: Supercritical fractionation; mate tea; c...
Jin-hua Qin - One of the best experts on this subject based on the ideXlab platform.
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Change in tea polyphenol and Purine Alkaloid composition during solid-state fungal fermentation of postfermented tea.
Journal of agricultural and food chemistry, 2012Co-Authors: Jin-hua Qin, Liang ZhangAbstract:The aim of this study was to evaluate tea polyphenol and Purine Alkaloid contents of pu-erh tea (Camellia assamica) in a fermentation solid system with Aspergillus niger and Aspergillus fumigatu. In addition, the objective was to find the major intermediate product during fermentation by HPLC–MSn analysis. The results showed the change of catechin, ester-catechins and gallic acid by quantitative analysis. In the early stages, the contents of ester-catechins were lightly increased. Then, ester-catechins were gradually degraded to produce catechins and gallic acid. Furthermore, a major metabolic intermediate compound of catechins was observed and elucidated by HPLC–DAD–MSn analysis. This study provided a reliable dynamic data description and metabolic pathway of tea polyphenols for postfermented pu-erh tea.
