The high content (about 39%) of polymeric tannins in tamarind (Tamarindus indica L.) seed husk (TSH) was demonstrated, and an extract (crude TSE) with a high content (about 94%) of polymeric tannins was prepared from TSH with a one pot extraction using ethanol/water (3:2, v/v). The crude TSE was further purified with Sephadex LH20 to give one fraction (metTSE) eluted with methanol/water (3:2, v/v) and another (acTSE) eluted with acetone/water (3:2, v/v). The tannins of acTSE were established as polymeric proanthocyanidins (PA) by 13C NMR spectroscopy; this was further confirmed by IR and UV spectroscopy, n-BuOH/HCl and vanillin assays, and from HPLC pattern. The ratio of procyanidins to prodelphinidins was 2:3, and the average degree of polymerization of acTSE was 7. Galloylated flavan-3-ols were not detected in acTSE. The main ingredients of metTSE were confirmed to be polymeric PA by 13C NMR spectroscopy. The antioxidant activities using DPPH and ABTS assays were investigated. The IC50 values of acTSE were 4.2±0.2 (DPPH assay) and 6.2±0.3 μg/mL (ABTS assay).
TsudaT., WatanabeM., OhshimaK., YamamotoA., KawakishiS., OsawaT. (1994) Antioxidative components isolated from the seed of tamarind (Tamarindus indica L.). Journal of Agricultural and Food Chemistry, 42, 2671–2674.
2.
KomutarinT., AzadiS., ButterworthL., KeilD., ChitsomboonB., SuttajitM., MeadeB.J. (2004) Extract of the seed coat of Tamarindus indica inhibits nitric oxide production by murine macrophages in vitro and in vivo. Food and Chemical Toxicology, 42, 649–58.
3.
LuengthanapholS., MongkholkhajornsilpD., DouglasS., DouglasP.L., PengsopaL., PongamphaiS. (2004) Extraction of antioxidants from sweet Thai tamarind seed coat-preliminary experiments. Journal of Food Engineering, 63, 247–252.
4.
AengwanichW., SuttajitM., SrikhunT., BoonsornT. (2009) Antibiotic effect of polyphenolic compound extracted from tamarind (Tamarindus indica L.) seed coat on productive performance of broilers. International Journal Poultry Sciences, 8, 749–751.
5.
SudjaroenY., HaubnerR., WürteleG., HullW.E., ErbenG., SpiegelhalderB., ChangbumrungS., BartschH., OwenR.W. (2005) Isolation and structure elucidation of phenolic antioxidants from Tamarind (Tamarindus indica L.) seeds and pericarp. Food and Chemical Toxicology, 43, 1673–1682.
6.
SiddhurajuP. (2007) Antioxidant activity of polyphenolic compounds extracted from defatted raw and dry heated Tamarindus indica seed coat. Lebensmittel-Wissenschaft und-Technologie, 40, 982–990.
7.
PovichitN., PhrutivorapongkulA., SuttajitM., ChaiyasutC., LeelapornpisidP. (2010) Phenolic content and in vitro inhibitory effects on oxidation and protein glycation of some Thai medicinal plants. Pakistan Journal of Pharmaceutical Sciences, 23, 403–408.
8.
PengZ., HayasakaY., IlandP.G., SeftonM., HojP., WatersE.J. (2000) Quantitative analysis of polymeric procyanidins (tannins) from grape (Vitis vinifera) seeds by reverse phase high-performance liquid chromatography. Journal of Agricultural and Food Chemistry, 49, 26–31.
9.
WeberH.A., HodgesA.E., GuthrieJ.R., O'BrienB.M., RobaughD., ClarkA.P., HarrisR.K., AlgaierJ.R., SmithC.S. (2007) Comparison of proanthocyanidins in commercial antioxidants: grape seed and pine bark extracts. Journal of Agricultural and Food Chemistry, 55, 148–156.
10.
AppeldoornM.M., VinckenJ.P., SandersM., HollmanP.C.H., GruppenH. (2009) Combined normal-phase and reversed-phase liquid chromatography/ESIMS as a tool to determine the molecular diversity of A-type procyanidins in peanut skins. Journal of Agricultural and Food Chemistry, 57, 6007–6013.
11.
CzochanskaZ., FooL.Y., NewmanR.H., PorterL.J. (1980) Polymeric proanthocyanidins. Stereochemistry, structural units, and molecular weight. Journal of the Chemical Society, Perkin Transactions1, 2278–2286.
12.
KennedyJ.A., HayasakaY., VidalS., WatersE.J., JonesG.P. (2001) Composition of grape skin proanthocyanidins at different stages of berry development. Journal of Agricultural and Food Chemistry, 49, 5348–5355.
13.
Es-SafiN.E., GuyotS., DucrotP.H. (2006) NMR, ESI/MS, and MALDI-TOF/MS analysis of pear juice polymeric proanthocyanidins with potent free radical scavenging activity. Journal of Agricultural and Food Chemistry, 54, 6969–6977.
14.
ZhangL.L., LinY.M. (2008) HPLC, NMR and MALDI-TOF MS analysis of condensed tannins from Lithocarpus glaber leaves with potent free radical scavenging activity. Molecules, 13, 2986–2997.
15.
KennedyJ.A., JonesG.P. (2001) Analysis of proanthocyanidin cleavage products following acid-catalysis in the presence of excess phloroglucinol. Journal of Agricultural and Food Chemistry, 49, 1740–1746.
16.
MagalhãesL.M., SegundoM.A., ReisS., LimaJLFC, TóthI.V., RangelAOSS. (2007) Automatic flow system for sequential determination of ABTS.+ scavenging capacity and Folin-Ciocalteu index: A comparative study in food products. Analytica Chimica Acta, 592, 193–201.
17.
YamaguchiT., TakamuraH., MatobaT., TeraoJ. (1998) HPLC method for evaluation of the free radical-scavenging activity of foods by using 1,1-diphenyl-2-picrylhydrazyl. Bioscience Biotechnology and Biochemistry, 62, 1201–1204.
18.
ButlerL.G., PriceM.L., BrothertonJ.E. (1982) Vanillin assay for proanthocyanidins (condensed tannins): modification of the solvent for estimation of the degree of polymerization. Journal of Agricultural and Food Chemistry, 30, 1087–1089.
19.
VermerrisW., NicholsonR. (2006) Isolation and identification of phenolic compounds. In: Phenolic compound biochemistry, V VermerrisW., NicholsonR. (Eds), Springer Science and Business Media, Florida, 1–276.
LiuD., ShiJ., IbarraA.C., KakudaY., XueS.J. (2008) The scavenging capacity and synergistic effects of lycopene, vitamin E, vitamin C, and β-carotene mixture on the DPPH free radical. Lebensmittel-Wissenschaft und-Technologie, 41, 1344–1349.
