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Yoshinori Saito
Nagasaki University
74Publications
12H-index
505Citations
Publications 74
Newest
#1Motoo Tori (Tokushima Bunri University)H-Index: 31
#2Yoshinori Saito (Nagasaki University)H-Index: 12
Last.Chiaki Kuroda (Rikkyo University)H-Index: 17
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Chemical constituents of Cremanthodium angustifolium, C. brunneopilosum, C. campanulatum, C. daochengense, C. discoideum, C. ellisii, C. helianthus, C. lineare, C. nobile, C. potaninii, C. principi...
#1Hitomi Morikawa (Nagasaki University)H-Index: 1
#2Keita Okuda (Nagasaki University)H-Index: 1
Last.Toshiki Tanaka (Nagasaki University)H-Index: 65
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Abstract Roasting of green tea causes oligomerization of tea catechins, which decreases the astringency. The aim of this study was to elucidate the oligomerization mechanism. The 13 C NMR spectrum of the oligomer fraction showed signals arising from catechin and sugar residues. Heating of epigallocatechin-3- O -gallate with 13 C-labeled glucose (150 °C for 2 h) suggested that condensation of sugars with catechin A-rings caused the oligomerization. The dimeric product obtained by heating for a sh...
#1Joanna Orejola (Nagasaki University)H-Index: 1
#2Mark Luz (Nagasaki University)H-Index: 1
Last.Toshiki Tanaka (Nagasaki University)H-Index: 65
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Abstract This study aimed to characterize and evaluate the cytotoxicities of ellagitannins from S. praecox fruit. Fractionation of an acetone extract of the fruit led to isolation of five new ellagitannins—stachyuranin D ( 15 ), stachyuranin E ( 16 ), stachyuranin F ( 17 ), stachyugluconin ( 18 ), and stachyuglyconin ( 19 )—along with seven ellagitannins previously isolated from S. praecox leaves and seven known ellagitannins isolated from Stachyuraceae for the first time. Two-dimensional NMR an...
#1Yoshinori Saito (Nagasaki University)H-Index: 12
#2Mayu Ichihara (Tokushima Bunri University)H-Index: 5
Last.Motoo Tori (Tokushima Bunri University)H-Index: 31
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The chemical constituents in the roots of 3 Cremanthodium campanulatum Diels (Asteraceae) samples collected in Yunnan and Sichuan Provinces, China, were chemically investigated. A total of 8 bisabo...
#1Yoshinori Saito (Nagasaki University)H-Index: 12
#2Saori Iga (Tokushima Bunri University)H-Index: 1
Last.Motoo Tori (Tokushima Bunri University)H-Index: 31
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Abstract Secobakkane B (C-6/C-7 cleaved secobakkane type aldehyde), secovirgaurenols B and C (C-8/C-9 cleaved secoeremophilane type), a 1β,10β-epoxyfuranoeremophilane, two 1β,10β-epoxyeremophilanolides, and fukinospirolide C (bakkane-type lactone), as well as 33 known compounds were isolated from three samples of Ligularia virgaurea collected in China. Two of the three analyzed samples were grouped in the neoadenostylone (N) type, and the rest, a mixture of the 6-hydroxyeuryopsyn (H) and cacalol...
#1Manami Era (Nagasaki University)H-Index: 1
#2Yosuke Matsuo (Nagasaki University)H-Index: 15
Last.Toshiki Tanaka (Nagasaki University)H-Index: 65
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Four new ellagitannin metabolites, penthorumnins A–D (1–3 and 5), were isolated from the dried stem of Penthorum chinense. The structures were determined using spectroscopic and chemical analysis as well as using computations that revealed the following: (1) the acyl group of penthorumnin A (1) has a unique cyclopentane carboxylic acid structure that is derived from a hexahydroxydiphenoyl (HHDP) group; (2) penthorumnin B (2) has a 2-carboxymethyl-2,3-dihydro-3-oxo-1H-indene-1-carboxylic acid str...
#1Yoshinori Saito (Nagasaki University)H-Index: 12
#2Yuko Shiosaki (Nagasaki University)
Last.Chiaki Kuroda (Rikkyo University)H-Index: 17
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Chemical constituents of Ligularia hookeri (Asteraceae) collected in Yunnan and Sichuan Provinces in China were examined for the first time. Seven furanoeremophilanes, five of which were new, as well as known bisabolane- and eudesmane-type sesquiterpenoids, were isolated. Spectroscopic evidence indicates that the previously reported 3 beta-(2'-methylpropenoyloxy)furanoeremophilan-15,6 beta-olide should be revised to 3 beta-(2'-methylpropenoyloxy)furanoeremophilan-15,6 alpha-olide.
#1Toshiki Tanaka (Nagasaki University)H-Index: 65
#2Yosuke Matsuo (Nagasaki University)
Last.Yoshinori Saito (Nagasaki University)H-Index: 12
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#1Yosuke Matsuo (Nagasaki University)H-Index: 15
#2Ryosuke Oowatashi (Nagasaki University)H-Index: 2
Last.Toshiki Tanaka (Nagasaki University)H-Index: 65
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Theaflavins are reddish-orange black tea pigments with a benzotropolone chromophore, and their various biological activities have been reported. Theaflavins are produced by oxidative coupling between catechol-type and pyrogallol-type catechins via bicyclo[3.2.1]octane-type intermediates. In this study, a new method for nonenzymatic biomimetic synthesis of theaflavins was developed using the DPPH radical as an oxidizing agent.
#1Yosuke Matsuo (Nagasaki University)H-Index: 15
#2Ayane Yoshida (Nagasaki University)H-Index: 1
Last.Toshiki Tanaka (Nagasaki University)H-Index: 65
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Goupiolones A and B are unique phenolic compounds with significant DNA-damaging activity. In this study, the structure of goupiolone B was revised on the basis of DFT calculations of the ¹³C NMR chemical shifts and biosynthetic considerations. The dibenzobicyclo[3.2.2]nonane skeleton of the revised structure suggested that goupiolone B was produced by oxidative coupling between catechol and goupiolone A, which was strongly supported by this biomimetic synthesis. Furthermore, the racemization of ...
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