title: Diastereomeric Ellagitannin Isomers from Penthorum chinense.
abstract: From the dried stem of Penthorum chinense (Penthoraceae), 1-O-galloyl-4,6-(R)-hexahydroxydiphenoyl (HHDP)-β-D-glucose and 2',4',6'-trihydroxyacetophenone 4'-O-[4,6-(R)-HHDP]-β-D-glucoside were isolated together with their (S)-HHDP isomers. Ellagitannins with a 4,6-(S)-HHDP-glucose moiety are widely distributed in the plant kingdom; however, 4,6-(R)-HHDP glucoses are extremely rare. Lowest-energy conformers of 1-O-galloyl-(S)- and (R)-HHDP-glucopyranoses were derived by density functional theory calculations, and the calculated (1)H and (13)C NMR chemical shifts and the (1)H-(1)H coupling constants were in agreement with the experimental values. The results revealed a conformational difference of the diastereomeric macrocyclic ester rings. In addition, a new compound, 1',3',5'-trihydroxybenzene 1'-O-[4,6-(S)-HHDP]-β-D-glucoside, was also isolated.
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University , 1-14 Bunkyo-Machi, Nagasaki 852-8521, Japan.
authors.forename: Manami
authors.initials: M
authors.lastname: Era
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University , 1-14 Bunkyo-Machi, Nagasaki 852-8521, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Matsuo
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University , 1-14 Bunkyo-Machi, Nagasaki 852-8521, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Shii
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University , 1-14 Bunkyo-Machi, Nagasaki 852-8521, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Saito
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University , 1-14 Bunkyo-Machi, Nagasaki 852-8521, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Institute for Applied Research in Medicine and Health, Macau University of Science and Technology , Taipa, Macau 999078, PR China.
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Jiang
mesh_terms: D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification*; D005947:Glucose / Q000032:analysis; D005960:Glucosides / Q000737:chemistry; D047348:Hydrolyzable Tannins / Q000737:chemistry / Q000302:isolation & purification*; D007536:Isomerism; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018547:Plant Stems / Q000737:chemistry; D031995:Saxifragaceae / Q000737:chemistry*
chemical_list: D004365:Drugs, Chinese Herbal; D005960:Glucosides; D047348:Hydrolyzable Tannins; C013515:ellagitannin; D005947:Glucose