title: Structure and biogenesis of jolkinin, a highly oxygenated ellagitannin from Euphorbia jolkinii.
abstract: A new ellagitannin, jolkinin (2), was isolated from the fresh whole plant of Euphorbia jolkinii, and its structure, including absolute configuration, was determined on the basis of spectroscopic and chemical evidence. A highly oxygenated acyl group with unique hexacyclic structure is attached to the 2,4-positions of 1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-beta-d-glucopyranose. The structural similarity to elaeocarpusin (4) suggests that jolkinin is produced by a condensation reaction between ascorbic acid and geraniin (1), the dominant ellagitannin in this plant, which contains a dehydrohexahydroxydiphenoyl group. A plausible mechanism for jolkinin formation is also proposed.
authors.affiliation: Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Gen-ichiro
authors.initials: G
authors.lastname: Nonaka
authors.forename: Itsuo
authors.initials: I
authors.lastname: Nishioka
mesh_terms: D028481:Euphorbia / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry; D047348:Hydrolyzable Tannins; D007564:Japan; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism; D013634:Tannins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D005960:Glucosides; D047348:Hydrolyzable Tannins; D013634:Tannins; C013515:ellagitannin; C488241:jolkinin; C024603:Geraniin