Oxford University Press (OUP) Acta Medica Okayama 1347-6947 89 6 2025 PNGase activity and free N-glycans in phloem fluid prepared from Nerium oleander (oleander tree) 872 875 EN Fuki Otaguro Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Yoshinobu Kimura Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Megumi Maeda Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Free N-glycans (FNGs) occur ubiquitously in growing plants. Recently, it was reported that these FNGs interact with auxin. In this study, we investigated whether PNGase activity responsible for producing the FNGs occurs in the extracellular fluid, where auxin is present during its polar transfer. Here, we report the occurrences of PNGase activity and FNGs in the phloem fluid. No potential conflict of interest relevant to this article was reported.

Frontiers Media SA Acta Medica Okayama 1664-462X 12 2021 Purification, Characterization, and Gene Expression of Rice Endo-beta-N-Acetylglucosaminidase, Endo-Os 647684 EN Megumi Maeda Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University Naoko Okamoto Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University Node Araki Department of Tumor Genetics and Biology, Graduate School of Medical Sciences, Kumamoto University Yoshinobu Kimura Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University In the endoplasmic reticulum-associated degradation system of plant and animal cells, high-mannose type free N-glycans (HMT-FNGs) are produced from misfolded glycoproteins prior to proteasomal degradation, and two enzymes, cytosolic peptide:N-glycanase (cPNGase) and endo-beta-N-acetylglucosaminidase (endo-beta-GlcNAc-ase), are involved in the deglycosylation. Although the physiological functions of these FNGs in plant growth and development remain to be elucidated, detailed characterization of cPNGase and endo-beta-GlcNAc-ase is required. In our previous work, we described the purification, characterization, and subcellular distribution of some plant endo-beta-GlcNAc-ases and preliminarily reported the gene information of rice endo-beta-GlcNAc-ase (Endo-Os). Furthermore, we analyzed the changes in gene expression of endo-beta-GlcNAc-ase during tomato fruit maturation and constructed a mutant line of Arabidopsis thaliana, in which the two endo-beta-GlcNAc-ase genes were knocked-out based on the Endo-Os gene. In this report, we describe the purification, characterization, amino acid sequence, and gene cloning of Endo-Os in detail. Purified Endo-Os, with an optimal pH of 6.5, showed high activity for high-mannose type N-glycans bearing the Man alpha 1-2Man alpha 1-3Man beta 1 unit; this substrate specificity was almost the same as that of other plant endo-beta-GlcNAc-ases, suggesting that Endo-Os plays a critical role in the production of HTM-FNGs in the cytosol. Electrospray ionization-mass spectrometry analysis of the tryptic peptides revealed 17 internal amino acid sequences, including the C terminus; the N-terminal sequence could not be identified due to chemical modification. These internal amino acid sequences were consistent with the amino acid sequence (UniProt ID: Q5W6R1) deduced from the Oryza sativa cDNA clone AK112067 (gene ID: Os05g0346500). Recombinant Endo-Os expressed in Escherichia coli using cDNA showed the same enzymatic properties as those of native Endo-Os. No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 1664-462X 11 2021 Cytosolic Free N-Glycans Are Retro-Transported Into the Endoplasmic Reticulum in Plant Cells 610124 EN Makoto Katsube Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University Natsuki Ebara Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University Megumi Maeda Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University Yoshinobu Kimura Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University During endoplasmic reticulum (ER)-associated degradation, free N-glycans (FNGs) are produced from misfolded nascent glycoproteins via the combination of the cytosolic peptide N-glycanase (cPNGase) and endo-beta-N-acetylglucosaminidase (ENGase) in the plant cytosol. The resulting high-mannose type (HMT)-FNGs, which carry one GlcNAc residue at the reducing end (GN1-FNGs), are ubiquitously found in developing plant cells. In a previous study, we found that HMT-FNGs assisted in protein folding and inhibited beta-amyloid fibril formation, suggesting a possible biofunction of FNGs involved in the protein folding system. However, whether these HMT-FNGs occur in the ER, an organelle involved in protein folding, remained unclear. On the contrary, we also reported the presence of plant complex type (PCT)-GN1-FNGs, which carry the Lewis(a) epitope at the non-reducing end, indicating that these FNGs had been fully processed in the Golgi apparatus. Since plant ENGase was active toward HMT-N-glycans but not PCT-N-glycans that carry beta 1-2xylosyl and/or alpha 1-3 fucosyl residue(s), these PCT-GN1-FNGs did not appear to be produced from fully processed glycoproteins that harbored PCT-N-glycans via ENGase activity. Interestingly, PCT-GN1-FNGs were found in the extracellular space, suggesting that HMT-GN1-FNGs formed in the cytosol might be transported back to the ER and processed in the Golgi apparatus through the protein secretion pathway. As the first step in elucidating the production mechanism of PCT-GN1-FNGs, we analyzed the structures of free oligosaccharides in plant microsomes and proved that HMT-FNGs (Man(9-7)GlcNAc(1) and Man(9-8)GlcNAc(2)) could be found in microsomes, which almost consist of the ER compartments. No potential conflict of interest relevant to this article was reported.

TAYLOR & FRANCIS Acta Medica Okayama 0916-8451 83 7 2019 Plant complex type free N-glycans occur in tomato xylem sap 1310 1314 EN Yuta Tsujimori Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Mikako Ogura Faculty of Agriculture, Division of Agricultural Science , Okayama University Md. Ziaur Rahman Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Megumi Maeda Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Yoshinobu Kimura Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Free N-glycans (FNGs) are ubiquitous in growing plants. Further, acidic peptide:N-glycanase is believed to be involved in the production of plant complex-type FNGs (PCT-FNGs) during the degradation of dysfunctional glycoproteins. However, the distribution of PCT-FNGs in growing plants has not been analyzed. Here, we report the occurrence of PCT-FNGs in the xylem sap of the stem of the tomato plant. No potential conflict of interest relevant to this article was reported.

Taylor & Francis Acta Medica Okayama 09168451 82 7 2018 Novel assay system for acidic Peptide:N-glycanase (aPNGase) activity in crude plant extract 1172 1175 EN Ryota Uemura Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Mikako Ogura Faculty of Agriculture , Okayama University Chihiro Matsumaru Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Tsuyoshi Akiyama Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Megumi Maeda Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Yoshinobu Kimura Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science , Okayama University Acidic peptide:N-glycanase (aPNGase) plays a pivotal role in plant glycoprotein turnover. For the construction of aPNGase-knockout or -overexpressing plants, a new method to detect the activity in crude plant extracts is required because endogenous peptidases present in the extract hamper enzyme assays using fluorescence-labeled N-glycopeptides as a substrate. In this study, we developed a new method for measuring aPNGase activity in crude extracts from plant materials No potential conflict of interest relevant to this article was reported.

Nature Publishing Group Acta Medica Okayama 2045-2322 7 1 2017 Synthesis of Sulfo-Sialic Acid Analogues: Potent Neuraminidase Inhibitors in Regards to Anomeric Functionality 8239 EN Christopher J. Vavrick Graduate School of Environmental and Life Science, Okayama University Chiaki Muto Graduate School of Environmental and Life Science, Okayama University Tomohisa Hasunuma Graduate School of Science, Technology and Innovation, Kobe University Yoshinobu Kimura Graduate School of Environmental and Life Science, Okayama University Michihiro Araki Graduate School of Science, Technology and Innovation, Kobe University Yan Wu CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences George F. Gao CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences Hiroshi Ohrui Yokohama College of Pharmacy Minoru Izumi Graduate School of Environmental and Life Science, Okayama University Hiromasa Kiyota Graduate School of Environmental and Life Science, Okayama University The design, synthesis and application of N-acetylneuraminic acid-derived compounds bearing anomeric sulfo functional groups are described. These novel compounds, which we refer to as sulfo-sialic acid analogues, include 2-decarboxy-2-deoxy-2-sulfo-N-acetylneuraminic acid and its 4-deoxy-3,4-dehydrogenated pseudoglycal. While 2-decarboxy-2-deoxy-2-sulfo-N-acetylneuraminic acid contains no further modifications of the 2-deoxy-pyranose ring, it is still a more potent inhibitor of avian-origin H5N1 neuraminidase (NA) and drug-resistant His275Tyr NA as compared to the oxocarbenium ion transition state analogue 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. The sulfo-sialic acid analogues described in this report are also more potent inhibitors of influenza NA (up to 40-fold) and bacterial NA (up to 8.5-fold) relative to the corresponding anomeric phosphonic acids. These results confirm that this novel anomeric sulfo modification offers great potential to improve the potency of next-generation NA inhibitors including covalent inhibitors. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 2186-7755 106 2017 Ginkgo biloba α-fucosidase with activity towards plant complex type N-glycans containing the Lewis a epitope: Purification and characterization 5 12 EN Satsuki Itano Graduate School of Environmental and life Science, Okayama University Megumi Maeda Graduate School of Environmental and life Science, Okayama University Md. Ziaur Rahman Institute of Food and Radiation Biology, Atomic Energy Research Establishment, Bangladesh Atomic Energy Commission Yoshinobu Kimura Graduate School of Environmental and life Science, Okayama University 　We have identified, and purified to homogeneity, a high molecular weight Ginkgo biloba α-fucosidase (α-fucosidase Gb, 120 kDa estimated by SDS‒PAGE) with activity against α-fucosylated oligosaccharides. When a Lewis a epitope-containing N-glycan was used as a substrate, α-fucosidase Gb showed optimum activity at approximately pH 5.5, suggesting that it functions in acidic environments such as the vacuole. It remains uncertain, however, whether this Ginkgo α-fucosidase belongs to the GH29 family, since its N-terminal sequence could not be determined, probably due to a chemical modification. α-Fucosidase Gb showed substantial activity towards the α1,3-fucosyl linkage in Lacto-N-fucopentaose III and an α1,4-fucosyl linkage in the Lewis a epitope found in plant complex type N-glycans, indicating an involvement in the degradation process of α-fucosylated oligosaccharides or N-glycoproteins. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 2186-7755 103 2014 Changes in Glycinin‒Digesting Protease Activity During Soybean Germination. 1 4 EN Md. Akhtaruzzaman Megumi Maeda Keiko Kitagawa Shigeaki Takagi Yoshinobu Kimura 　Changes in glycinin-digesting protease activity during soybean germination have been investigated. The glycinin-digesting protease activities of imbibed or germinated soybean seed were assayed by RP‒HPLC using a tryptic peptide from CM‒glycinin or by SDS‒PAGE using CM‒glycinin as the endogenous substrate. Proteolytic activities of the germinated soybean seeds were found through the whole period of germination, the activities were maintained significantly unchanged during germination for 4 days, and then those specific activities declined slowly. AE‒HPLC analysis of the glycinin-digesting protease in the imbibed or germinated soybean seeds showed unchanged peaks corresponding to glycinin- digesting activity, suggesting that the glycinin-digesting protease was not induced during germination but had already been synthesized during seed maturation. No potential conflict of interest relevant to this article was reported.

Japan Society for Bioscience, Biotechnology, and Agrochemistry Acta Medica Okayama 0916-8451 71 4 2007 Evidence for new beta 1-3 galactosyltransferase activity involved in biosynthesis of unusual N-glycan harboring T-antigen in Apis mellifera 1111 1114 EN Yoshinobu Kimura Sho Sakamura Takayuki Ushijima Yoichiro Hama Hiroyuki Kajiura Kazuhito Fujiyama Kiyoshi Okihara Ken Hashimoto Hiroyuki Sugimoto Hideo Yamada In a previous study (Y. Kimura et al., Biosci. Biotechnol Biochem., 70, 2583-2587, 2006), we found that new complex type N-glycans harboring Thomsen-Friedenreich antigen (Ga1 beta 1-3GalNAc) unit occur on royal jelly glycoproteins, suggesting the involvement of a new beta 1-3galactosyltransferase in the synthesis of the unusual complex type N-glycans. So far, such beta 1-3galactosyltransferase activity, which can transfer galactosyl residues with the beta 1-3 linkage to beta 1-4 GalNAc residues in N-glycan, has not been found among any eucaryotic cells. But using GalNAc(2)GlcNAc(2)Man(3)-GlcNAc(2)-PA as acceptor N-glycan, we detected the beta 1-3 galactosyltransferase activity in membrane fraction prepared from honeybee cephalic portions. This result indicates that honeybee expresses a unique beta 1-3 galactosyltransferase involved in biosynthesis of the unusual N-glycan containing a tumor related antigen in the hypopharyngeal gland. No potential conflict of interest relevant to this article was reported.

岡山大学環境管理センター Acta Medica Okayama 11 1989 編集後記 74 EN Yoshinobu Kimura No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 85 1 1996 Zeaxanthin分子集合体の分光学的挙動とその形態 7 13 EN Shigeaki Takagi Junko Itani Yoshinobu Kimura Kunio Takeda Lutein, one of the xanthophylls, can be dispersed in various aqueous solutions, for example, protein solution, dilute acetone solution, dilute sodium dodecyl sulfate (SDS) solution, dodecyl trimethylammonium bromide solution, hen egg yolk phosphatidyl-choline (PC) liposome, or digalactosyldiglyceride liposome, to from chiral helical aggregates which acquire an optical activity in the visible region, and have a left handed helical structure. In this report, zeaxanthin, a structural isomer of lutein, was subjected to investigation as to whether zeaxanthin formed the chiral helical aggregate. When zeaxanthin was dispersed in SDS solution, some differences from lutein were obserbed. (1) CD spectrum of positive Cotten effect was shown, which was the reverse of lutein. (2) SDS concentration giving the reversion of the CD spectrum pattern was higher (3.5mM) than that of lutein (0.6mM). IN spite of these differences, however, the results showed that zeaxanthin molecules also associated to from molecular aggregate in such a manner performing π*-π*interaction at conjjugated polyene sites. zeaxanthin dispersed in PC liposome gave both left and right-handed helical structure under presence of Ca2+ at alkaline condition in comparison with lutein's left-handed structure. This result may depend on the fact that synthesized racemic zeaxanthin is subjected to this experiment. Those results gave the general conclusion that xanthophylls had the same basic types of behavior for making molecular aggregate in aqueous dispersion. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 84 1 1995 ウズラ反転小腸によるホウレンソウ葉カロテノイドの吸収とレチノイド生成及び血中カロテノイドの卵黄への移行機作について 1 6 EN Shigeaki Takagi Akira Miki Yoshinobu Kimura Katsunori Satoh At incubation with spinach carotenoid of inverted quail intestine,β-carotene was quickly absorbed into the intestinal mucosa and then changed to retinol,passing out of the mucosa.The majority of the xanthophyll including lutein,after absorption into the mucosa,passed out of the mucosa in intact form,and the velocities varied per xanthophylls in descending order of lutein,antheraxanthin,and violaxanthin.It became apparent that out of the absorbed xanthophylls,chiefly lutein was incorporated into quail serum LDL,where it was transported into the egg yolk and accumulated. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 87 1 1998 Changes in Asparagine-linked Sugar Chains of Glycoproteins in Ricinus communis Seeds during Callus Induction 35 41 EN Yoshinobu Kimura Shigeaki Takagi Using glycotechnology procedures, structural changes in asparagine-linked sugar chains (N-glycans) of glycoproteins in Ricinus communis seeds during dedifferentiation (callus induction) have been explored. N-Glycans were released from the glycoproteins in the 2,4-D derived callus tissues by hydrazinolysis, and the resulting oligosaccharides were N-acetylated and coupled with 2-aminopyridine. Structures of the purified pyridylaminated (PA-) N-glycans could be deduced by two-dimensional (2D) sugar chain mapping method. Structural analysis clearly showed that the relative amount of high-mannose type N-glycans of the endospermic glycoproteins decreased as the plant cells dedifferentiated, while that of complex type N-glycans increased. this observation suggested that enhancement of expression and/or activation of certain α-mannosidase(s) involved in N-glycan processing could occur during dedifferentiation of plant cells. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 87 1 1998 ラット小腸粘膜β-carotene-15,15'-dioxygenase の活性測定法の確立と酵素化学的性質 29 34 EN Shigeaki Takagi Masanori Watanabe Akiko Nakajima Yoshinobu Kimura A central cleavage at 15, 15' position of　βーcarotene has not been an established theory in absorption and metabolism, because an exenteric cleavage of βーcarotene for producing apocarotenals has been suggested. We considered that this problem was based only on the imperfection of the assay method for βーcarotene-15,15'-dioxygenase (BCDC) activity in vitro, and tried the establishment of this assay method by investigating cofactor activities together with other assy conditions. BCDO activity of rat intestina mucosa homogenate could not be detected with the known method by Goodman et al. SH reagents (GSH or DTT) and nicotinamide (NA) were essential for BCDO assay. NADH could take place with NA, but the product was retinol instead of retinal. NAD+ partially inhibited the enzyme activity. Optimum concentrations of other cofactors were decided under the following conditions : 1 mM GSH, 1 mM Fe2+, and 10 mM glycocholate. From these results, a good reproducibility of the in vitro assay for BCDO activity was obtained, and it was confirmed that the central cleavage theory presented by Goodman was reasonable. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 88 1 1999 Structural Analysis of Free N-Glycans in Bamboo (Phyllostachys heterocycla) Shoots 19 24 EN Yoshinobu Kimura Tatsuya Ueyama Free N-glycans, the high-mannose-type and the plant complex-type, have been found in bamboo shoots. These free N-glycans were coupled with 2-aminopyridine and purified by gel filtration, Con A-Sepharose affinity chromatography, reversed-phase HPLC, and size-fractionation HPLC. The structures of these pyridylaminated free N-glycans were identified by two-dimensional sugar chain mapping, exomannosidase digestions, and ion-spray tandem mass spectrometry. The structual analyses showed that the various free high-mannose type sugar chains having one GlcNAc(Man8-5GlcNAc1) and free xylose/fucose containing sugar chains having the chitobiose segment occur in the developing bamboo shoots, suggesting that an endo-β-N-acetylglucosaminidase should produce the former structures, and a peptide: N-glycanase should produce the latter structures. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 88 1 1999 バリダマイシン生成菌培養液から抗細菌性抗生物質ノカルダミンの分離・精製 13 17 EN Eiji Higashide Yoshiharu Omatsu Suemi Inoue Yoshinobu Kimura Hiroshi Kanzaki Shuhei Nakajima An antibacterial active against P. mirabilis was isolated from the culture of Streptomyces hygroscopicus subsp. limoneus, validamycin producer. The antibiotic was found to be produced with a non-validamycin producing condition. The antibiotic was identified as nocardamine with the analytical data, IR, 1H-NMR and 13C-NMR spectra. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 89 1 2000 Purification and Properties of Aryl-α-mannosidase from Microsomal Fraction of Developing Ricinus communis Endosperms 9 14 EN Masafumi Yamai Yoshinobu Kimura An α-mannosidase, which would be involved in N-linked glycoprotein metabolism, was purified and characterized from microsomal fraction of developing Ricinus communis endosperms. The purified enzyme with 43 kDa on SDS-PAGE showed maximal activity at pH5.0 and 50℃, when p-nitrophenyl-α-mannopyranoside was used as a substrate. α-Mannosidase activity was inhibited by EDTA and the reduced activity was rescued by addition of Zn2+ or Ca2+, suggesting this α-mannosidase should be a metal enzyme. Ricinus aryl-α-mannosidase was able to convert the Man6GlcNAc2-PA and Man5GlcNAc2-PA to Man4GlcNAc2-PA but was completely inactive toward Man4GlcNAc2-PA, Man4Xy11GlcNAc2-PA and GlcNAc1Man5GlcNAc2-PA. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 90 1 2001 The Possibility that Plant Complex Type FreeN-Glycans Localize in Cell Wall Fraction 15 18 EN Yoshinobu Kimura Masashi Suzuki In this report, we bring up the possibility that complex type free N-glycans may localize in cell wall fraction of developing seeds (Ginkgo biloba seeds). Several free N-glycans extracted by mild acid hydrolysis of cell wall fraction were coupled with 2-aminopyridine and purified by gel filtration, size-fractionation HPLC, and reversed-phase HPLC. The structures of the pyridylaminated free N-glycans were identified by two-dimensional sugar chain mapping, α-1,2-mannosidase digestions, and ionspray tandem mass spectrometry. The structural analyses showed that highmannose type free N-glycans having one GlcNAc residue (Man8-5GlcNAc1) and plant complex type free N-glycans having the N-acetyl chitobiose unit also occur in the call wall fraction of the developing Ginkgo seeds. However, quantitative analysis of such free N-glycans showed that the plant complex type free glycans found in small amounts(～3%) in the cytosolic fraction accounted for nearly 40% of total free N-glycans, This observation suggested that the complex type free N-glycans might occur and localized in the cell wall fraction. No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 81 1 1993 ラット小腸粘膜レチナール還元酵素活性の測定法の確立と酵素化学的性質 1 7 EN Shigeaki Takagi Yuko Fujii Yoshinobu Kimura ラット小腸粘膜のレチナール還元酵素(RRase)のin vitroにおける活性測定法を確立すると共に,その系におけるレチナールの還元及び酸化反応について調べた.小腸のRRaseは摂取されたβ-カロテンなどプロビタミンAから生じるレチナールをレチノールに変える作用が主たる役割と考えられる酵素である.小腸粘膜ホモジェネートを用いてin vitroでRRase活性を測定すると,比活性の再現性が乏しく,またホモジェネート中でのRRaseの速やかな失活が起こる.これを防ぐためには,酵素調製用緩衝液にニコチンアミドやNADHなどのニコチンアミド誘導体を2mM以上加えるのが有効であることを見いだした.最適pHは4.3,cofactorとしてGSHを要求する点はすでにGoodmanらが報告している通りであるが,GSH以外のチオール試薬もGSHと同様に有効であった.EDTA添加によって活性を殆ど失うが,Ca2+,Mg2+の添加で活性が回復することから,これらが金属イオンとして要求されていると思われる.RRaseのkm値は83.3μMであり,200μM以上のレチナールを用いて活性測定を行うと120minで基質レチナールの40%以上が還元される.このことは,レチナール還元反応がレチノール生成に大きく傾いた反応であることを示すものである。 No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 80 1 1992 ホウレンソウ葉カロテノイドがヒト白血病細胞株の分化に及ぼす影響 7 15 EN Shigeaki Takagi Kazuhisa Hizume Yoshinobu Kimura Jun Minowada Yoshinobu Matsuo ホウレンソウ緑葉カロテノイドのヒト骨髄性白血病細胞株に対する分化誘導活性を調べると同時に,その目的に合致する活性測定法の選択,及び細胞株の選択を行った. ホウレンソウ葉カロテンはML-1,ML-2及びHL-60細胞の分化誘導活性を示し,ルテイン,ビオラキサンチン,ネオキサンチンのキサントフィル類は活性を示さなかった.ホウレンソウ葉カロテンは細胞の生存率を80-85%に低下させるが,キサントフィルの毒性は極めて弱い.そのカロテンの分化誘導活性はレテインとの共集合体を作らせることによって増加しており,これはカロテンと細胞との相互作用の増加を示すものである.カロテノイドを用いた場合の分化誘導活性測定法としてはNBT還元法と間接蛍光抗体法が有用であった.試験細胞として上記3細胞株はいずれも有用であるが,なかでもHL-60はホウレンソウ葉カロテンによる分化誘導活性を最も強く受ける。 No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 78 1 1991 β-Carotene及びホウレンソウカロテノイドのラットにおける吸収と蓄積 1 9 EN Shigeaki Takagi Yoshiro Sato Yoshinobu Kimura 植物性食品に広く含まれるカロテノイドのうち,β-caroteneなどはプロビタミンA効果以外に抗ガン,抗酸化防止効果などが注目されているが,カロテノイドの消化・吸収機構及び体内分布に関する基礎的知見は少ない,カロテノイド非蓄積動物と呼ばれるラットについてβ-carotene単独投与及びホウレンソウカロテノイドとを投与し,それぞれにおける各カロテノイドの吸収挙動と吸収カロテノイド及び生成retinolの体内存在状態を調べた.β-caroteneは単独に投与すると約50%の吸収率となるが,xanthophyll共存下では数%にまで低下する.これはβ-caroteneの吸収をxanthophyllが妨害していることを示す.β-caroteneは肝臓にもっとも多く蓄積されneoxanthinがこれを次いでいる.もっとも多く吸収されたluteinは肝臓にはほとんど検出されず,血液中に少量存在していた.このような両カロテノイドの挙動はカロテノイド非蓄積動物に特徴的なものと考えられる.カロテノイドを含まない飼料を投与すると一時的にretinolの血中濃度は上昇し,肝濃度は低下するが,カロテノイドを投与すると恒常的血中retinol濃度に速やかに戻る.β-carotene及びホウレンソウカロテノイドを25日間投与したときのretinolの正味増加量はそれぞれ474μgと522μgであるが血中のretinolレベルはほとんど変化していない.このことは肝に充分量のretinol存在しておれば血中retinolレベルはほぼ一定に保たれる制御作用のあることを示している。 No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 77 1 1991 緑葉カロテノイドのニワトリ卵黄への選択的移行とその機構 1 8 EN Shigeaki Takagi Hiroyuki Nakano Yoshinobu Kimura Yasuhiro Kondo Akira Tanabe ニワトリにおける緑葉カロテノイドの吸収と体組織分布について部分的に明らかにするとともに,とくに卵黄へのルテインの集中選択的蓄積に関する知見を得た. 投与した緑葉カロテノイド各々のみかけ吸収率は50～65%とカロテノイドによる差は認められないが,卵黄への蓄積量及び蓄積率はキサントフィルが高く,なかでもルテインはそのみかけ吸収量の25%が卵黄に蓄積している.これに対し,β－カロチンはみかけ吸収量のわずか0.6%しか蓄積せず,卵黄全カロテノイドに占める割合もルテインの約85%に対し1%である. 3日間の短期投与による緑葉カロテノイドの肝,卵巣,血液への正味蓄積量において,ルテインは肝よりも卵巣に6倍以上の速度で蓄積するのに対し,他のキサントフィル及びβ－カロテンは肝に多く蓄積する傾向がある.このことは緑葉カロテノイドのうちルテインがとくに卵黄に蓄積しやすいことを示すものである。 No potential conflict of interest relevant to this article was reported.

岡山大学農学部 Acta Medica Okayama 0474-0254 75 1 1990 A Seasonal Variation of Carotenoid Composition in Green Leaves and Effect of Environmental Factors on It+ 1 7 EN Shigeaki Takagi Fumiaki Kishi Kentaro Nakajima Yoshinobu Kimura Mikio Nakano Carotenoid compositions of green leaves are varied with the passage of season. β-Carotene, one of the major carotenoid, is rich in summer and poor in spring, autumn and winter , while lutein, the other major, shows the opposite direction to β-carotene. These phenomena were confirmed to be always found in every plants, in both annual and perennial plants or in both herbaceous and woody plants. This variation was also confirmed to be seasonal and periodical on using green leaves of both evergreen and deciduous trees . The examinations for grapevine grown under different temperatures and light intensities revealed that these seasonal variations were mainly based on temperature. These results will provide important informations for both plant physiology and food nutrition. No potential conflict of interest relevant to this article was reported.