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Yoshinori Saito
Nagasaki University
Organic chemistryChemistryAsteraceaeBotanyStereochemistry
85Publications
12H-index
553Citations
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Publications 88
Newest
#1Joanna OrejolaH-Index: 1
#2Manami EraH-Index: 1
Last. Toshiki TanakaH-Index: 67
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Abstract Nupharanin (1), the first ellagitannin with dehydrohexahydroxydiphenoyl esters at the 1,4-positions of α- d -glucose, was isolated from the fresh rhizome of Nuphar japonicum. Based on spectroscopic evidence, the structure was determined to be 1,4-(S)-dehydrohexahydroxydiphenoyl-2-galloyl-3,6-(R)-hexahydroxydiphenoyl-α- d -glucopyranose. The structure was supported by spectroscopic studies of acetonyl derivatives of 1 and its partial hydrolysate. In addition, unusual oxidative cleavage o...
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#1Manami EraH-Index: 1
#2Yosuke Matsuo (Nagasaki University)H-Index: 16
Last. Toshiki TanakaH-Index: 67
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Amariin is an ellagitannin with two dehydrohexahydroxydiphenoyl (DHHDP) moieties connecting glucose 2,4- and 3,6-hydroxy groups. This tannin is predominant in the young leaves of Triadica sebifera and Carpinus japonica. However, as the leaves grow, the 3,6-DHHDP is converted to its reduced form, the hexahydroxydiphenoyl (HHDP) group, to generate geraniin, a predominant ellagitannin of the matured leaves. The purified amariin is unstable in aqueous solution, and the 3,6-(R)-DHHDP is spontaneously...
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#1Hatsumi WakamatsuH-Index: 1
Last. Toshiki TanakaH-Index: 67
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The leaves of Castanopsis sieboldii (Fagaceae) contain characteristic hexahydroxydiphenoyl (HHDP) esters of 28-O-glucosyl 2α,3β,23,24-tetrahydroxyolean- and urs-12-en-28-oic acids. In this study, uncharacterized substances were detected in the young leaves, which are not observed in the mature leaves. Preliminary HPLC analyses indicated that the substances had dehydro-HHDP (DHHDP) ester groups; however, the esters were unstable and decomposed during extraction. Therefore, the compounds were isol...
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#1Yasuko Okamoto (Tokushima Bunri University)H-Index: 12
#2Yumi Nakadozono (Rikkyo University)
Last. Ryo Hanai (Rikkyo University)H-Index: 22
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The composition of root chemicals was studied for 7 samples of Ligularia tongolensis collected in Yunnan and Sichuan Provinces of China. The structures of 2 new 3β-angeloyloxy-6β-acyloxyfuranoeremo...
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#1Motoo Tori (Tokushima Bunri University)H-Index: 30
#2Yoshinori Saito (Nagasaki University)H-Index: 12
Last. Chiaki Kuroda (Rikkyo University)H-Index: 20
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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...
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#1Joanna Orejola (Nagasaki University)H-Index: 1
#2Mark Anthony de Vera Luz (Nagasaki University)H-Index: 1
Last. Toshiki Tanaka (Nagasaki University)H-Index: 67
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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...
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#1Yoshinori Saito (Nagasaki University)H-Index: 12
#2Mayu Ichihara (Tokushima Bunri University)H-Index: 5
Last. Motoo Tori (Tokushima Bunri University)H-Index: 30
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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...
1 CitationsSource
#1Hitomi Morikawa (Nagasaki University)H-Index: 1
#2Keita Okuda (Nagasaki University)H-Index: 1
Last. Toshiki Tanaka (Nagasaki University)H-Index: 67
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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 13C NMR spectrum of the oligomer fraction showed signals arising from catechin and sugar residues. Heating of epigallocatechin-3-O-gallate with 13C-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 shorte...
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#1Yoshinori Saito (Nagasaki University)H-Index: 12
#2Saori Iga (Tokushima Bunri University)H-Index: 1
Last. Motoo Tori (Tokushima Bunri University)H-Index: 30
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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...
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#1Manami Era (Nagasaki University)H-Index: 1
#2Yosuke Matsuo (Nagasaki University)H-Index: 16
Last. Toshiki Tanaka (Nagasaki University)H-Index: 67
view all 6 authors...
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...
1 CitationsSource
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