81571-72-4Relevant academic research and scientific papers
Biosynthesis of the dimeric ellagitannin, cornusiin E, in Tellima grandiflora
Niemetz, Ruth,Schilling, Gerhard,Gross, Georg G.
, p. 109 - 114 (2007/10/03)
First evidence for the in vitro synthesis of a dimeric ellagitannin has been obtained with cell-free extracts from the weed Tellima gratidiflora (fringe cups, Saxifragaceae). Partially purified enzyme preparations from leaves of this plant catalyzed the oxidation of 1,2,3,4,6-pentagalloyl-β -D-glucose to the monomeric ellagitannin, tellimagrandin II, followed by oxidative coupling of two units of this intermediate to yield a dimeric derivative. Chemical degradation, MALDI-TOF mass spectrometry, 1H and 13C nuclear magnetic resonance, and CD spectroscopy were employed to identify this enzyme reaction product as cornusiin E which is characterized by a (S)-valoneoyl bridge between glucose-positions 2, 4′ and 6′. This result was supported by comparison with data obtained for cornusiin E that had been isolated from leaves of intact T. grandiflora plants. No indication for the earlier proposed existence of rugosin D (an isomer with a 1,4′6′-bound valoneoyl unit) in T. grandiflora has been obtained in this investigation.
REACTION OF DEHYDROELLAGITANNINS WITH L-CYSTEINE METHYL ESTER
Tanaka, Takashi,Fujisaki, Hiroshi,Nonaka, Gen-ichiro,Nishioka, Itsuo
, p. 375 - 383 (2007/10/02)
Reaction of dehydroellagitannins (e.g. 1) with L-cysteine methyl ester (5) at room temperature yielded the condensation products (e.g. 3 and 4), together with a partial hydrolysate (e.g. 2), while heating the mixture at 80 deg C afforded 4 and the hydrolysate (2) in fairly good yields.In addition, reduction of a dehydrohexahydroxydiphenoyl ester group to a hexahydroxy-diphenoyl group with thiols is also described.
Constituents of Geranium thunbergii Sieb. et Zucc. Part 12. Hydrated Stereostructure and Equilibration of Geraniin
Okuda, Takuo,Yoshida, Takashi,Hatano, Tsutomu
, p. 9 - 14 (2007/10/02)
The structure of geraniin is (1), in which the cyclohexenetrione moiety is attached to O-4 of glucose.It forms a hydrated six-membered hemiacetal-ring structure (1a) in the crystalline state, and an equilibrium mixture of (1a) and a hydrated five-membered hemiacetal-ring structure (1b) upon the mutarotation.The absolute configurations are also represented by (1a) and (1b).
