- Tannins and Related Compounds. Part 37.1 Isolation and Structure Elucidation of Elaeocarpusin, a Novel Ellagitannin from Elaeocarpus sylvestris var. Ellipticus
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A new hydrolysable tannin, elaeocarpusin, isolated from the leaves of Elaeocarpus sylvestris var.Ellipticus, has been characterized on the basis of chemical, spectroscopic, and X-ray analyses to be a novel ellagitannin in which a unique acid ester group probably derived by a condensation of a hexahydroxydiphenoyl group and dehydroascorbic acid is attached to the 2,4-positions of 1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-D-glucopyranose (corilagin).This structural feature suggest the possibility of the participation of dehydroascorbic acid as a co-enzyme in oxidative metabolism of the hexahydroxydiphenoyl group to the corresponding dehydro group.
- Tanaka, Takashi,Nonaka, Gen-ichiro,Nishioka, Itsuo,Miyahara, Kazumoto,Kawasaki, Toshio
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p. 369 - 376
(2007/10/02)
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- ELAEOCARPUSIN, A PROTO-TYPE OF GERANIIN FROM GERANIUM THUNBERGII
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The co-occurence of geraniin (2) and a novel ellagitannin, elaeocarpusin (1) in Geranium thunbergii has been demonstrated.In addition, enzymatic transformation of 1 into 2 has been achieved, leading to the evidence that dehydroascorbic acid (4) participates as a co-enzyme in the oxidative metabolism of the hexahyroxydiphenoyl group to the corresponding dehydro group.Furthermore, flavan-3-ol derivatives and gallotannins containing a glucose and a quinic acid core have been isolated, together with previously reported ellagitannins.Keywords - Geranium thunbergii; Geraniaceae; elaeocarpusin; geraniin; ellagitannin; dehydrohexahydroxydiphenic acid; hexahydroxydiphenic acid; dehydroascorbic acid; transformation; oxidative metabolism
- Nonaka, Gen-ichiro,Morimoto, Satoshi,Nishioka, Itsuo
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p. 941 - 943
(2007/10/02)
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