Oligomeric proanthocyanidins from mangosteen pericarps.
Oligomeric proanthocyanidins were extracted from mangosteen pericarps and fractionated by a Sephadex LH-20 column to give 0.66% yield (dry matter). (13)C and (1)H NMR signals showed the presence of predominantly procyanidins together with a few prodelphinidin units along with small amounts of stereoisomers of afzelechin/epiafzelechin, catechin/epicatechin, and gallocatechin/epigallocatechin. Depolymerization with benzylmercaptan resulted in epicatechin thioether as the major product, and the mean degree of polymerization was determined to be 6.6. The electron spray ionization-mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectra revealed the dominant B type oligomers with mainly epicatechin units and with a small amount of A type oligomers. The isolated proanthocyanidins are potent peroxyl radical scavengers as evidenced by the high oxygen radical scavenging capacity at 1.7 x 10 (4) micromol TE/g, much higher than that of pine bark and grape seed extracts.
Fu
Caili
C
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Republic of Singapore.
Loo
Alvin Eng Kiat
AE
Chia
Fiona Ping Ping
FP
Huang
Dejian
D
D005591:Chemical Fractionation; D029762:Garcinia mangostana / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D044945:Proanthocyanidins / Q000032:analysis* / Q000737:chemistry; D012639:Seeds / Q000737:chemistry*; D044004:Xanthones / Q000032:analysis
D044945:Proanthocyanidins; D044004:Xanthones; C021053:mangostin