title: Isolation and antioxidant activity of zeylaniin A, a new macrocyclic ellagitannin from Syzygium zeylanicum leaves.
abstract: Methanol extract obtained from Syzygium zeylanicum leaves exhibited potent antioxidant activity. The water extract obtained from this methanol extract by sequential extraction with hexane, chloroform, ethylacetate, and n-butanol also showed the strongest antioxidant activity among extracts. This water extract was further fractionated by column chromatography with various concentrations of methanol solutions. Among the 6 resultant fractions, the fraction developed with 20% methanol exhibited the most potent antioxidant activity. The one peak among the three major HPLC peaks in this fraction was isolated and purified using a preparative HPLC. The structure of a pure compound was elucidated as a novel macrocyclic ellagitannin using a (1)H/(13)C NMR and a high-resolution electrospray ionization mass spectrometer. This newly isolated compound, which was named zeylaniin A, exhibited potent antioxidant activities in the assays of DPPH, oxygen radical absorbance capacity, and malonadehyde/gas chromatography. S. zeylanicum leaves can be a possible source of natural antioxidants.
authors.affiliation: Institute of Environmental Science for Human Life, Ochanomizu University, Bunkyo-Ku, Tokyo, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Nomi
authors.forename: Saki
authors.initials: S
authors.lastname: Shimizu
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Sone
authors.forename: Mai Truong
authors.initials: MT
authors.lastname: Tuyet
authors.forename: Tien Pham
authors.initials: TP
authors.lastname: Gia
authors.forename: Masumi
authors.initials: M
authors.lastname: Kamiyama
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shibamoto
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Shindo
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Otsuka
mesh_terms: D000975:Antioxidants / Q000032:analysis / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D047348:Hydrolyzable Tannins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D000432:Methanol; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry*; D027842:Syzygium / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D047348:Hydrolyzable Tannins; D010936:Plant Extracts; C013515:ellagitannin; C579162:zeylaniin A; D000432:Methanol